Tag Archive | potting soil

Seedlings For Your Garden: 12 Tips

2022

Updated 5/21/2024

seedlings, zucchini

Starting Seedlings For Your Garden

Busy spring! This lengthy article focuses on starting and caring for seedlings and getting them established in the garden. If I’m not working on the seedlings, I’m working in the gardens, creating new beds and expanding those started last fall and winter. Winter weather was delightfully mild to allow planting right through the cold season. The weeds and I have come to an understanding, and in the next article, I’ll tell you how in “Patches for Pollinators”.

Foremost on the agenda has been starting plants to sell at our local Elkin Farmers’ Market. It’s been a challenge this year, keeping plants in good condition with high heat, heavy humidity, and frequent rainstorms. If I had a climate-controlled greenhouse, there might have been fewer losses. But, for the most part, my company, Wellspring Gardens, is producing more seedlings than I can sell at the market.

Some of that overproduction is destined for the vegetable gardens. It will yield small harvests of produce to sell at the market in addition to what’s needed in the kitchen. This is new territory for me, adding produce to the plants offered at the farmers’ market.

I might even consider canning, which I’ve never done…but let’s not get ahead of ourselves. That would be helpful, though, considering the rapidly rising prices at the grocery store. For that reason alone—the impact of rampant inflation on our wallets—it’s wise to learn how to grow at least a few vegetables.

The sun’s path across the sky, Charlotte NC.

Watching how the sun tracks across the sky from month to month reveals good spots for the sun worshipers and areas where leafy greens should thrive in partial sun. This is my first summer in this house. The massive oak trees create shifting shade patterns that cause me to periodically rethink the plans.

So, let’s begin!

12 Tips For Starting Seeds

1. Start with clean materials for seedlings.

Sweet pepper ‘Glow’, started in 9-cell packs.

This calls for packaged seedling mix or fine-grained potting soil. Don’t use “dirt” from the garden, with its pathogens, insects, weed seeds, and worms that disrupt soil structure around tiny roots. In addition to the unknowns lurking in garden soil, its high clay content causes drainage issues in containers.

Potting soil that has a lot of coarse materials, such as pine fines (bits of pine bark), can be improved by sifting the soil. I use a clean plastic pot with small holes in the bottom. Fill the pot partway with the soil, and shake it vigorously up and down over the containers. Do the same thing when covering seeds.

Soil used previously for potted plants is not a good medium for your seedlings. It’s often depleted of nutrients, might contain pathogens, and the organic matter has partially decomposed. If it’s only one season old, it’s probably safe for transplanting potted annuals, when mixed with fresh potting soil, or incorporated into the backfill for that new sourwood tree. Or simply throw it under the shrubs or into the compost pile (never in the trash!).

Because seedlings are susceptible to soil-borne diseases, play it safe and start with pasteurized bagged seedling mix or potting soil. This, however, doesn’t guarantee a successful outcome, as many disease spores are air-borne. But we can increase the odds of success by using clean materials.

When reusing cell packs, pots, and flats for seeding, wash them in a 10% bleach solution, and rinse well before proceeding. Don’t smoke around plants, and wash hands thoroughly before working with them. Tobacco and other plants in the nightshade family (Solanaceae, including tomato, pepper, eggplant, and potato) can fall prey to the same disease organisms. Spores can transfer from tobacco products to your hands to the plants.

Pasteurizing Potting Soil

For bagged soil that’s questionable, you can pasteurize it in the oven. Don’t heat soil that contains timed release fertilizers. Use an oven-safe covered pot or baking dish, wet the soil, and heat the oven to 200°F. When the soil registers 140° on a meat thermometer, lower the oven temperature and maintain soil at that temperature for 30 minutes. This kills most pathogens. Wait for it to dry somewhat and to cool thoroughly before using. Various websites recommend different temperature levels from 140° to 300°. At the high end, however, beneficial microbes are killed off as well.

Let it cool down outdoors. Considering the pervasive “earthy” odor coming from hot soil, you might prefer buying a new bag of seedling mix or accept a small risk with the open bag in the garage.

Another method of pasteurizing (not sterilizing) soil is to place a heat-resistant container of soil in a black plastic bag. Place the bag in a sunny place outdoors on a warm day, and let the sun do the work for you. This is called solarization, and can raise the temperature inside the bag to 140-160°F. To prevent damage to the beneficial microbes, take the temperature, and maintain it at 140° for 30 minutes, opening the bag a bit to prevent overheating.

Most bagged potting soils and seedling mixes already have been heat-treated to eliminate pests. Close the bag securely and store in a cool dark place. The last and only time I pasteurized soil was nearly 50 years ago because that’s what the experts recommended.

2. Grow disease resistant varieties…

While fungicide and bactericide formulations—both organic and conventional—are available, I’d rather grow disease resistant varieties and not rely on spraying. Keep in mind that resistance is not 100% effective, particularly when plants are exposed to stressful weather or cultural conditions.

Certain varieties are more flavorful than others, but all well-grown fruits and vegetables from your own garden taste better than those purchased from grocery stores. Picked when vine-ripened perfect, anything coming from the garden will be superior to what’s found elsewhere except, perhaps, at farmers’ markets and farm stands. Freshly picked produce also has the highest nutrient content.

Digging in the garden is great exercise; proceed slowly at first. Working outside in nature feels good, and self-sufficiency is never amiss. A few steps from the back door gathering a green onion, spinach, dinosaur kale, and a little ripe sweet pepper for the veggie omelet is more rewarding than I can describe. You’ll see!

Those are just a few of the many benefits of growing our own vegetables. Using disease resistant varieties, if available, makes the job so much easier. Many new gardeners gave up after having suffered the disappointment of losing an entire crop to early blight or bacterial leaf spot. And we also have to deal with deer, rabbits, and insects!

Although this article concentrates primarily on edibles, flowering plants also have their own set of disease organisms. Again, look for resistant varieties, grow them in conditions that don’t favor infection, and look for remedies at the garden center.

…Especially Tomato Seedlings

Disease beginning on ‘Rutgers’ tomato.

Tomatoes and peppers, two of the most popular crops for home vegetable gardens, are vulnerable to many diseases. They’re caused by fungal, bacterial, or viral pathogens. In some areas, nematodes also can be a problem. Usually, we can harvest some fruits before disease claims them, but resistant plants last longer in the garden. Plants infected with viruses should be removed and destroyed. For fungal and bacterial pathogens, products at garden centers will help. Always read the labels.

Tomato diseases include Alternaria stem canker, early blight, late blight (Phytophthora; very few varieties are resistant to this one), Fusarium wilt, grey leaf spot, leaf mold, tobacco mosaic virus, tomato mosaic virus, tomato spotted wilt virus, and Verticillium wilt. Catalog listings use initials to indicate disease resistance. For tomatoes, AS, EB, LB, F, GLS, LM, TMV, ToMV, TSWV, and V, respectively, represent those diseases.

Tomatoes are weedy plants and normally produce good crops, despite many organisms that target them. Peppers are susceptible to several races of bacterial leaf spot, and basil to basil downy mildew. Some zinnias are plagued by powdery mildew. Weather conditions, such as high humidity and frequent rain, exacerbate these disease problems.

Most hybrid (or “F1”) tomatoes have some resistance to one or more pathogens, but not to all of them. ‘Big Beef Plus’ is resistant to a wide variety of diseases. ‘Damsel’ and ‘Defiant PhR’ are resistant to late blight. Hybrid seeds carry a higher price than open pollinated varieties due to the cost of research that developed them and the extra steps needed to produce hybrid seeds each year.

It’s so hot out there!

If you live in a hot climate, look for tomato varieties that have been bred to produce better at high temperatures. The pollen in tomatoes and peppers, and others, can die at high temperatures. While these plants are comfortable at 65-80°F, pollen dies above 88°, 90°, or 92°, depending on the cultivar. No pollination = no fruits! A reference to “heat” or to the “south” in the plant’s variety name indicates its higher tolerance for heat.

Researchers are investigating thermo-tolerant genetics in wild tomato species (Solanum pimpinellifolium) and incorporating them in tomato breeding programs.

One trick to preserve viable pollen is lightly shading the plant in the hot afternoon hours. Attach shade fabric—a black woven mesh—to a support over and on the west side of the tomato or pepper plants. This provides a decrease of up to several degrees in hot climates or temporarily during a heat wave. In the photo, above, mesh bags from the grocery store protect fruits from squirrels and sun scald, and lightly shade new flowers and their pollen from high heat.

The young ‘Estiva’ tomato plants (“estiva” refers to summer), a hybrid bred for heat tolerance and great taste, lost most of their diseased bottom leaves in heavy rains, but those little fruits are still growing! I’ll plant them out this weekend, after the temperatures drop well below the 108° heat index value we have now. Recent weather has been in the record-breaking mid- to high 90’s F, with high humidity. Not my favorite conditions to dig in the garden…so I don’t. I was not bred for heat tolerance!

***Update***: ‘Estiva’ tomatoes endured this hot summer and produced fruits past the first fall frosts. I covered them on chilly nights to ripen the last of the fruits. These were among the last tomatoes to succumb to the cold, in mid-November. Autumn 2022

A Few More Tomato Tips

Your best defense against tomato disease, in addition to growing disease resistant varieties, includes these tips:

Stake them. Tall indeterminate types need a 6-8′ tall stake, taller for some.
Space them farther apart, at least 3½-4′.
Thin the vines to 3 or 4 main stems by removing excess suckers.
Remove leaves on the bottom 12″ of the plants after they’ve become established.
Locate them where a breeze blows through the garden. These first 5 tips address increasing air circulation around and through the tomato plants.
Give them lots of direct sun—a minimum of 7 or 8 hours. The more sun they receive, the shorter the window of opportunity for pathogens to germinate on damp leaf surfaces.
Mulch the soil under the plants to prevent disease spores lying dormant in the soil from splashing onto and infecting the foliage. More on Page 4.
Water in the morning to early afternoon so all foliage is dry going into the night. Try to keep the foliage dry at all times and avoid handling wet foliage.
Water established plants heavily (1½”/week) when needed, but avoid giving little sips every day. Young seedlings need more frequent watering until their root systems expand.
Clip off leaves that show early symptoms (yellowing, spotting), and dip your pruners in alcohol when moving from plant to plant.
Don’t smoke near the garden, and wash hands thoroughly before working with plants.
Rotate your crops. Don’t plant a member of the Solanaceae family where any members have grown in the past 3-4 years. There’s more about crop rotation on Page 4.

All plants grown with good soil preparation, good air circulation, proper watering techniques, adequate sun, and appropriate fertilization are less stressed. Less stress equates to lower infection rates.

Growing Heirloom Seedlings

: These “black” heirloom tomatoes are higher in beneficial pigments called anthocyanins, which are powerful antioxidants. ‘Cherokee Purple’ (above) originated near the NC/TN border, and had been grown by the Cherokee for generations before seeds became widely available in the early 1990’s. ‘Black Prince’ (left), is a high-yielding variety, shown before fruits darkened.

Heirloom tomatoes are always in demand because of their exceptionally good flavor. Heirlooms are open pollinated, which means gardeners can save seeds from fully ripened fruits each year for the next season’s garden. Because they’re not F1 hybrids but have been breeding true, for the most part, for many decades, heirlooms retain their traits from one generation to the next.

These varieties, however, don’t have much built-in disease resistance. Nevertheless, I’m growing a few heirlooms, and spacing them 4′ apart for improved air circulation. We’ll see what happens.

Commercially grown tomatoes must be able to survive long distance transportation and handling without damage. They’re picked early, when green or first showing color. Varieties of these tomatoes have skins that normally are tougher.

Heirloom tomatoes have more desirable thinner skins and, therefore, travel poorly. So, you won’t see them in grocery stores unless those stores buy from local farms. Heirloom tomatoes from the grocery store might cost $5.00/lb. or more! So, yes, it is worth growing a couple of heirloom tomato plants in our gardens.

A few prolonged and heavy rainy periods this spring almost wiped out certain tomato varieties, namely ‘Carmello’, ‘Brandywine’, and ‘German Johnson’. I still have a few that show less damage than others. ‘Black Krim’ and ‘Cherokee Purple’ are doing fairly well, although they are heirlooms. Most of the remaining plants will be set in the garden. There’s usually a breeze blowing through the property, and by spacing them appropriately, I should get plenty of fruits.

Basil Downy Mildew

First symptom of BDM: yellow blotches between the main veins.

Although this dreaded disease targets only basil, it hasn’t appeared yet this year. But I’m prepared.

Last year, I grew ‘Rutgers Obsession DMR’ (DMR = Downy Mildew Resistant), an acceptable substitute for our beloved ‘Genovese’ and other susceptible sweet basils. Last year’s ‘Obsession’ did not develop any basil downy mildew (BDM)—not one speck—although wet and humid weather presented a worthy challenge. Other basil varieties in the ground or in pots succumbed to the disease within a week of infection…even young seedlings.

This year, I’m growing ‘Rutgers Obsession DMR’ and also ‘Rutgers Devotion DMR’ outside all summer. In addition, I’m seeding the old favorites, including ‘Genovese’, ‘Italian Large Leaf’, Thai basil ‘Siam Queen’, ‘Marseillais Dwarf’, and ‘Tuscany’, a lettuce-leaf basil. A few non-resistant basil plants will come indoors at night when warranted, as described below. But I’ll stop seeding susceptible varieties, except for a few pots, and concentrate on the resistant ones for the farmers’ market if the disease appears in the neighborhood.

Several other BDM resistant varieties can be purchased as seeds or as started plants.

Avoid High Humidity

Healthy sweet basil, in a pot.

If you want to grow your favorite basil varieties that are not resistant to BDM, there is a way to prevent a total loss.

BDM spores move up from the south on the breeze or on infected plants shipped into the area. The spores don’t overwinter in cold climates. If spores land on a susceptible variety, they need a relative humidity above 80-85% for a couple of hours in order to germinate.

Even during pleasant weather, the relative humidity can reach 90% or higher in the 2-3 hours around dawn. That’s when the temperature is usually the coolest and, therefore, the relative humidity is the highest.

When plants show early symptoms of BDM, remove the affected leaves. Take potted basil plants indoors for the night, every night. Indoor conditions never reach those high humidity levels, so you can still grow your preferred basil varieties successfully with a little effort. Remember to place the plants back outdoors after the sun has been up for a couple of hours.

Follow this regimen during rainy weather, although the plants might need to spend a day or two inside. Find the brightest spot to keep them during their temporary stay indoors. If possible, provide some artificial light. Unless it’s wilting, avoid watering basil indoors. Less sunlight means the plant won’t be photosynthesizing optimally or using much water, and wet soil can initiate root rot.

Headings

Page 1: 1. Start with clean materials for seedlings. (Pasteurizing Potting Soil), 2. Grow disease resistant varieties… (…Especially Tomato Seedlings, It’s so hot out there!, A Few More Tomato Tips, Growing Heirloom Seedlings, Basil Downy Mildew, Avoid High Humidity)

Page 2: 3. Timing is important for seedlings. (The Fall Growing Season, Keeping Records, The Cooperative Extension Service, Starting Seedlings Outdoors, Don’t Start Seedlings Too Early, Cool Season Crops, Extending the Growing Season, Seedlings Transplanted Into Bigger Pots, Bunching Onions, The Brassicas, Brassicas In My Garden, Lettuce), 4. Is the temperature suitable for seedlings? (Miniature Incandescent Lights For Warmth, Water Temperature)

Page 3: 5. Start seedlings in small batches. (My Simple Infrastructure), 6. Seedlings need strong light. (Growing Seedlings Under Shop Lights), 7. Cull the weaklings and anomalies. 8. Prevent damping-off disease from killing your seedlings. (Actinovate), 9. Seedlings and plants need fertilizer. (The Elements, Read the Label)

Page 4: 10. Prepare the soil for your transplants. (Start With Good Drainage, Air Pore Space, Gypsum and Lime, Add Nutrient-Rich Amendments, Bury It), 11. Try succession planting for maximum yield. (Crop Rotation, Mulch), 12. Stop the pests before they ruin your garden. (Slugs and Snails, Larvae of Moths and Butterflies, Spider Mites and Thrips, Deer and Rabbits), Concluding

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Herb Gardens: How To Grow Herbs In Pots

May11

2021

Updated 3/14/2024

Herb Gardens: The Scents and Flavors of Summer

Fresh ‘Genovese’ basil for the garden salad…savory French thyme on grilled fish…chives and flat parsley to enliven the egg salad and browned potatoes. Yummy! This lengthy article describes how you can plant and enjoy growing herb gardens in containers. Growing potted herbs on the balcony or the sunny patio is the perfect solution if you have no garden space.

Potted herb gardens can be moved around to get just the right amount of sunlight the plants need. They can enjoy the morning sun on one side of the deck, and a few additional hours of afternoon sun on the other. As the sun’s arc changes from one season to the next, you can reposition the plants to capture the most light.

Several years ago, a gentleman asked me to pot herbs into a large strawberry jar. He traveled frequently between his residence and a summer home at the beach. Because he was a keen cook, he planned to take this herb garden with him to the next kitchen, wherever it was. So, if not prohibited where you’ll be traveling, consider taking your herb garden with you on your next road trip!

The Gift That Keeps On Giving

Place herb gardens on the picnic table for family and guests to sample as they enjoy the day’s barbecue. And then, in autumn, you can continue the harvest by growing them in sunny windows indoors.

Using herbs to flavor foods might help you kick the salt habit, or at least decrease its consumption. In addition to their wonderful flavors, herbs have high concentrations of beneficial antioxidants, which contribute to our well-being. In decreasing order, oregano, rosemary, parsley, basil, and thyme contain the most antioxidants among the common herbs.

I’ve sold herb gardens as wedding or birthday presents, for Mother’s Day, Father’s Day, Christmas, and as housewarming gifts. Families purchased herb gardens for retiring parents, who planned to devote more time to gardening. Over decades of selling potted plants, I estimate that about half of these delightful combinations were given as gifts.

Choosing the Right Containers for Herb Gardens

Style and Size

Visit any well-stocked garden center and you’ll see an extensive selection of terra cotta (clay), stoneware, ceramic, wood, and inexpensive plastic pots. Containers are available in all sizes and shapes. Plain or ornate finishes reflect modern, rustic, or classic styles. You’ll also find containers specially fitted for deck railings or for hanging on a wall. Plant a half whiskey barrel with one or more mint varieties, and let them take over…in the pot, that is.

Some ceramics are glazed with materials that should not be used with edible plants. There might be a sticker on the bottom indicating this.

Rabbits are cute, but…

Small clay pots dry out faster than large non-porous pots. Just one day too many in direct sun without water could kill the plants. Lining a clay pot with food-grade plastic and poking a few holes in the bottom will slow the evaporation to a degree. To be sure, your herb gardens—especially small ones—will need daily checking.

Potting herbs in hanging baskets is a great solution if you live where deer and rabbits are waiting for the instant you turn your back. They’re particularly attracted to parsley, cilantro, and dill.

Herbs need excellent drainage, so always choose pots that have holes in the bottom. Other than that requirement, just select the pots that appeal to you. Many gardeners look for a consistent style, favoring pots that harmonize with each other and with the setting.

Window Boxes

Clay pots for herb gardens.

A popular container for herb gardens is the window box. Window boxes come in many styles, from quite simple to highly ornate. They’re available in terra cotta (lower shelf in photo, above), plastic, and lined or unlined wood. Plastic containers often have plugs in the drainage holes; remove them to ensure proper drainage.

You can hang them outside windows in securely anchored frames; lighter weight containers are a safer bet. Or simply place them on a brick wall, along a sidewalk, or at the edge of a sunny patio. Several herbs in clay pots look charming clustered together on a table. Where wind is a concern, use heavier pots, but don’t place them where they could blow off the balcony to the sidewalk and harm someone.

Cracking

Handle clay pots carefully so they won’t crack. Clay pots might tolerate one or a few seasons of freezing weather; eventually most will begin to spall or crack. When clay absorbs water, and the water expands as it freezes, the clay degrades. Denser terra cotta (Italian for “baked earth”) survives more winters than softer clay.

This clay pot (photo, right) spent almost a decade outside, and it cracked this past winter. Until it crumbles, it will serve some purpose in the garden. I usually used Italian clay pots for my plant business and acknowledge that even better-quality pottery has limits.

Switching herbs into frost-resistant pots where winters are cold is one option. Other options include growing them indoors, in a cold frame, or in a conservatory—in other words, where the pots won’t freeze.

Tuscan Style

Years ago, I planted two herb gardens for a customer in Potomac, Maryland. They sat on a low stone wall surrounding a sunny Mediterranean-style garden. The Italian clay window boxes were over 4′ long and weighed more than 50 pounds empty. They were beautiful when finished—all those shades of green, purple, gray, variegated white and yellow—and the fragrances!

Even without flowers, potted herb gardens have their own unmistakable charm. Green algae and that white coating (efflorescence, from mineral salts) building up on clay pots won’t harm the plants but will amplify the rustic factor. And, yes, you can clean it off if you prefer.

Long Toms

Long toms, also called rose pots, are taller than they are wide (top shelf and part of next one, in photo under “Window Boxes”). Variegated lemon thyme or prostrate rosemary cascading over the side are perfect choices.

These pots are available in tiny sizes only 2″ wide, but 4″, 5″, and 6″ pots are more useful. Offer small herb containers as party favors for special occasions or use them to assign seating around the table.

While in Maryland, I potted herbs into 3″ stainless steel long toms for the tables at a popular seafood restaurant. I switched them out every couple of weeks.

I used to purchase clay long toms from a wholesale supplier in Baltimore. They normally came without drainage holes, so I added them, using a reversible drill and a masonry bit. Easy.

Plain Pots

“Azalea” pots are 3/4 as tall as they are wide.

Reusing what you have sitting around the garage is most economical.

Clean out those 12″ hanging baskets that held annuals last year, and repurpose them for herb gardens, with or without the wires. Green plastic pots last longer than white ones, which degrade faster in direct sun.

Empty the tired old soil into the shrub gardens and purchase new potting soil for your project. Some plants, particularly basil, are susceptible to several soil borne diseases. Starting with clean materials, therefore, is critical for their success. Wipe down used pots with a 10% bleach solution, rinse, and air-dry…for basil, at least.

Azalea pots are a bit shorter than they are wide and lend a more anchored look to potted plants. I prefer azalea pots over standard pots (height = width). It’s a personal choice, of course. You can pot them up with one plant or use a larger pot for a few plants.

Topiary

Rosemary and lavender topiary standards (the lollipop shape) look great in clay azalea pots, with some moss growing on the soil surface. Grow them indoors, in full sun, where they’re protected from hard winter freezes. But keeping them outdoors—even in chilly weather—ensures they get enough direct sunlight.

Try training the woody herbs “quasi-bonsai” style, with knobby stems, a few little weeds, and a fallen “log” embedded in the moss. Allowing the clay to mellow with algae and efflorescence, and those pots aren’t so plain after all.

Strawberry Pots

Lemon thyme in a clay strawberry jar.

Planting a strawberry jar is a bit more complicated, so it deserves a post of its own. If your attempts at planting a strawberry pot have been less than successful, refer to this article for solutions.

Pot Color

A fine point often overlooked in container gardening is the color of the pot. In summer, with scorching sun bearing down on a dark pot, that heat transfers to the soil. Consequently, the root system will be sparse on the hot side of the pot. Plants are happier without this stress.

You can alleviate their discomfort by shading the root system in summer with smaller pots of heat tolerant plants, such as dwarf zinnias or vinca. Or use white pots in hot weather to lower the temperature.

In autumn, I plant cool season greens and herbs in black nursery pots. Dark colors absorb more energy from the sun. Warming the soil a moderate amount helps limit the deep freeze in winter. The longer the roots can function, the more foliage I’ll be able to pick.

Curiously, clay pots with moist soil can feel cooler to the touch. This is due to evaporative cooling, where the temperature decreases as water evaporates from the surface. So, even in hot weather, a clay pot won’t feel as hot as most other pots. Your skin performs the same function.

Choosing pot colors might not be an option. Alternatively, plant herbs that dislike heat (such as cilantro) on the cooler north (northern hemisphere) or east side of the pot.

Choosing the Right Plants for Herb Gardens

A Proper Fit

First, decide which herbs you want to grow. Look for smaller varieties of the herbs you use in cooking, choosing young but well-rooted transplants. These will adapt better to containers than full size varieties. Sometimes there’s not much choice; maybe only ‘Italian Large Leaf’ basil is available. Okay, I’d rather have it than no basil at all, so there are 4 options when using large-growing herbs:

use fewer herbs in the herb garden to make room for the big basil
keep the basil in the combination pot, but cut it back more frequently
find a larger pot for the herb garden
grow this large basil by itself

We need to find a balance between plant size and available space relative to what other plants need. You can fit a few plants together, but they suffer when cramming all the herbs you like into too small a container. Plants growing in pots, however, don’t grow as large as those in the ground.

Seeds and Transplants

Seeds can be sown directly in the pots, but thin them once they sprout. Remember that some species are very slow to germinate, and you most likely will have better success with transplants. For new gardeners, I suggest buying young plants for now, and perhaps experimenting with seeds during the summer. But if the herbs you need are available only as seed, go for it.

Garden centers and farmers’ markets offer a wide variety of herbs grown as transplants. Some growers start them from seed, cuttings, or plugs (very young plants) several times a year. In one growing season, you might find dozens of varieties of basil alone! So, shop around for the local herb lady, and request certain plants she might grow for you.

I included a section on Propagating Herbs, which you’ll find on Page 5.

What’s the Difference Between Herbs and Spices?

: Cilantro, the herb.

: Coriander, the spice.

Although we use the two terms interchangeably, there is a difference between them. Herbs are leaves of edible plants, and the focus of this article. Spices comprise all other parts of edible plants—bark, seeds, roots, fruits, and flower parts.

Cilantro leaves and coriander seeds come from the same plant, but those interested in this minor technicality differentiate between the herb and the spice.

Turmeric, ginger, vanilla extract, nutmeg, cinnamon, and black pepper are spices that we keep in the pantry. Saffron, the world’s most expensive spice, comes from the 3 threadlike female parts in a fall-blooming Crocus sativus flower.

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Headings:

Page 1: The Gift That Keeps On Giving, Choosing the Right Containers for Herb Gardens (Style and Size, Window Boxes, Long Toms, Plain Pots, Pot Color), Choosing the Right Plants for Herb Gardens (A Proper Fit, Seeds and Transplants, What’s the Difference Between Herbs and Spices?)

Page 2: Which Herbs Are Annuals? Biennials? Perennials?

Page 3: Herb Gardens Close To the Kitchen, Combination Pots, Potting Up Herb Gardens, How To Maintain Herb Gardens (Light, Natural Sunlight, Artificial Light)

Page 4: Tips For Watering Herb Gardens (Transpiration, Why Plants Wilt, Testing for Moisture, From Season To Season, Water Temperature), Fertilizing Herb Gardens (Organic or Synthetic?, Macronutrients and Micronutrients, How Often To Fertilize Herbs, When We Don’t Fertilize, The Taste Test), Temperature (As Temperatures Change)

Page 5: Common Pests (Better Options To Eradicate Pests, Bacillus Thuringiensis, Horticultural Oil, Organic Sluggo, Plain Water), Girth Control (It’s Thyme For Drying, Which Herbs Dry Well?), Renovating Herb Gardens (Propagating Herbs)

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How To Transplant Houseplants

Aug27

2019

Updated 9/26/2024

Time To Transplant Houseplants?

As the end of the growing season approaches, we need to prioritize all the chores that need attention. Do the houseplants require transplanting? The plants that summered outdoors must come back inside soon, before frost damages the foliage or kills the plants.

They’ve been luxuriating on the porch, in higher humidity and brighter light than they usually receive inside. It’s no wonder they look fabulous! So, reintroduce them to indoor conditions while the days are still somewhat long and before the furnace kicks on and dries the air.

Perennials that looked picture perfect in May now look a little stressed after those record high temperatures. And the tired vegetable garden needs fresh compost or aged manure before setting the fall crops.

In a few weeks, flowering bulbs will arrive at garden centers…with pansies, violas, snapdragons, dusty miller, and Heuchera, trailing ivy, and hardy grasses. You’ve been dreaming of those beautiful combination planters, like the ones you saw last autumn at the garden center. But first things first.

Should We Transplant Houseplants Now?

Let’s start with the houseplants. Exposing tropicals to cooling temperatures outdoors, as autumn takes hold, could stress your houseplants. And some of those plants are pleading for attention right now.

While certain plants can tolerate cooler temperatures (cyclamen, ferns, English ivy, succulents, ponytail palm), others can’t. The aroids (peace lily, Dieffenbachia, Anthurium, Philodendron, Alocasia, Chinese evergreen, pothos), prayer plants (Calathea, Maranta), and some of the begonias, for example, should come indoors before temperatures dip below 60°F.

Although they won’t be killed by a few nights in the 50’s, or even the 40’s, you don’t want to prolong their discomfort. Chilling stresses many of our tropical houseplants, and can rot roots and disfigure foliage.

Inspect Them First

You probably won’t need to transplant houseplants, summering on the porch, that were repotted in the spring. All you need to do now is to inspect them for insects and spider mites before bringing them indoors. Check the bottom of the pot for slugs and sowbugs hiding around the drainage hole.

Clean up the leaves, too, and remove any that are discolored, insect-eaten, or damaged. Peel away the entire leaf, so none of the leaf stems (petioles) remain that later will turn yellow or brown.

After the inspection, wipe down the pots, wash the saucers, and place the plants in front of the windows where they seemed to thrive last winter.

Horticultural Oil

Scale insects on Ficus neriifolia. Leaves are 7/16″ wide.

The dwarf Ficus neriifolia contracted a scale infestation, so I sprayed it with a horticultural oil solution. For insects and mites, horticultural oil works very well. It smothers the pests and is safe to use on most plants, including edibles.

Wiping the horticultural oil solution on smooth leaves (fiddle-leaf fig, pothos, peace lily) with a soft sponge removes dust, grime, and residue from water and fertilizers. It gives them a nice luster without appearing artificial. Read the label; I prefer to use less oil than is recommended on the label—to start with, anyway. Horticultural oil makes surfaces slippery, so be careful.

The fiddle-leaf fig, Ficus lyrata.

**Do Your Houseplants Actually Need Bigger Pots?**

Evergreen bonsai.

Knowing if the plant needs repotting, when to repot, and how large a pot to use is half the battle.

Does it wilt often? Perhaps instead of repotting, the plant needs to be deeply watered. Or maybe the roots have rotted in waterlogged soil, or the water rushes right through without moistening the soil.

I’ve seen a lot of dead plants over the years, and many simply were in pots that were too large. “Aren’t we supposed to transplant houseplants every year, just like our children outgrow their shoes every year?” No; once they have matured, plants can stay potbound for quite some time.

“If I transplant houseplants into bigger pots, won’t that make them grow faster and bigger?” No, another myth! If you transplant houseplants into pots twice the size they need, they more likely will die faster.

Large pots hold large quantities of soil and water. When the moisture is not used by the plant, the sodden mass just sits there, cutting off the oxygen supply and rotting the roots. So, if the entire volume is not tightly filled with roots, the plant doesn’t need to be repotted.

Many houseplants like being potbound. English ivy (Hedera helix), pothos (Epipremnum aureum), Philodendron, palm trees, Ficus trees, African violets, succulents, snake plants (formerly Sansevieria, now Dracaena), and bonsai prefer somewhat cramped quarters. Many potted herbs (rosemary, lavender, chives, sage, thyme) also fare better when potbound. But, in order to ensure good health, gardeners must provide nutrients according to the needs of the particular plant, and according to the time of year.

It’s helpful to know the habits and preferences for each kind of plant. For example, although the 4′ tall variegated snake plant (Dracaena trifasciata ‘Laurentii’) eventually will need a 10″ or 12″ pot, its cousin, the dwarf bird’s nest species (D. hahnii), can stay in a 4″ or 5″ pot for many years!

Fertilizing Houseplants

Most tropical plants spending the winter indoors won’t need fertilizer until late winter or early spring. If they continue to grow and look healthy, and they’re receiving good light, though, diluted solutions (1/4 to 1/2 strength) can be added every 4 to 6 weeks. Err on the side of using less fertilizer in winter.

As long as they’re properly watered and fertilized, your plants can remain perfectly happy while potbound. In fact, they’re easier to manage this way, since there’s less likelihood of overwatering. But you’ll have to water more frequently.

Look for products formulated for foliage houseplants or for flowering plants. They’re available in several forms: timed-release prills (use a low dose from fall through winter), liquids, granules, and soluble crystals. Read the label.

Fungus Gnats

Plants in smaller pots are less susceptible to diseases, root rot from overwatering, and fungus gnats. Ever have those annoying little “fruit flies” around your houseplants? The simplest remedy is to allow the soil surface to dry out.

Female fungus gnats lay eggs on moist soil. When the tiny larval worms emerge, they eat small roots, sap on cuttings, fungus, and organic matter in the top inch or two of the soil. Let the surface of the soil dry before watering again, and you’ll have fewer fungus gnats. See if adding a 1/2-1″ layer of pine fines as a mulch might prevent gnats from laying eggs.

Yellow sticky cards are good for catching flying insects. A card placed horizontally near the plants, on the pot’s rim, or in a sunny window attracts the most gnats.

Save the Spider!

A green spider plant.

The spider plant in the 4″ pot that your girlfriend gave you two months ago is literally crawling out of the pot. She propagated it from one of her own plants, so it has sentimental value.

Spider plants, related to other strong-rooted Asparagaceae (formerly Liliaceae) family members, develop roots that circle around the inside of the pot. The vigorously growing roots raise the entire plant higher in the pot, opening up air spaces around the root ball. This dries out the finer roots, and water gushes immediately through the drainage holes without moistening the soil. Clearly, it’s time to work on this one.

When Should I Transplant Houseplants?

A good time to transplant houseplants is in spring to mid- or late summer. Plants that recover slowly (for example, succulents) should be repotted, if needed, by mid-summer. In autumn and winter, plants receive fewer hours of daylight, photosynthesizing at a reduced level. Our slower growing tropicals don’t grow much foliage in autumn and in winter. And roots also are reluctant to grow.

Cooler temperatures, compared to the balmy summer days spent on the porch, cause systems to slow down. So, trying to force plants to grow at a time when they’re entering semi-dormancy often does more harm than good. Plopping a plant’s almost dormant root system into wet soil and expecting it to grow is asking the plant to do something against its nature. It would rather stay semi-dormant.

Providing a greenhouse atmosphere—warm, humid, and sunny—keeps your houseplants in much better condition, even through the shortest days of winter. Optimal light levels increase rates of photosynthesis, respiration, and transpiration. As a result, they might grow almost as fast as they did in June.

But most of us deal with dryer air, energy-saving chilly nights, and dim lighting (in the plants’ eyes) until the hyacinths bloom outside.

Plants, both indoors and out, take on renewed vigor once the days lengthen closer to springtime. Some of us humans do, too.

How Big Should the Pots Be?

Succulent dish garden in ceramic bonsai tray.

I’ve grown dwarf peperomias and miniature succulents, such as Echeveria minima and Haworthia truncata, in 2″ pots for many years. Since the succulents are prone to rot in wet soil, keeping them very potbound decreases the chances. There simply isn’t that much soil in the little clay pot, and it dries fast in direct sunlight.

Most of the succulents I enjoy growing are on the small side, anyway. Almost all are in 1½” to 4″ pots, and others have been planted in larger, but shallow, bonsai trays.

I brought with me from Maryland a 4½” pot of Drimiopsis kirkii, one of the African leopard lilies, and it has yet to be repotted into a larger pot, 6 years later. Its cousin, Drimiopsis maculata, however, grows from bulbs which multiply faster than those of D. kirkii. So, most of the D. maculata plants get divided more often, but they’re still in 4½” pots. Older plants are moved into 6″ pots, and remain crowded until divided.

Dracaena hahnii, the dwarf snake plant, lived happily for years in a 4½” pot. The small, glossy-leaved Spathiphyllum wallissii would have complained if it had been bumped up into anything larger than its 6½” plastic pot.

We’ve had this miniature cyclamen for years.

A pink flowering miniature cyclamen stays in its 4½” pot (photo, above), year after year. Now, in late summer, it is coming out of dormancy and beginning to grow new foliage, contrary to what most other plants are doing. That’s because its growth cycle calls for cool to cold, but not freezing, temperatures in order to set flower buds. It will be fertilized accordingly, for a full canopy of marbled leaves.

The plant’s habit and its root structure help determine the required pot size. In general, transplant houseplants into pots that are only 1″ to 2″ wider, and only if they need it.

The Old Weeping Fig

Variegated weeping fig.

A weeping fig (Ficus benjamina), given time, will grow to the ceiling. Instead of raising the roof, its height can be managed by “aesthetically” cutting stems back in the spring, when it will respond faster.

I grew a variegated weeping fig in a 14″ pot for about 15 years, in front of a big window that received a few hours of morning sun. When the tree grew to almost 8′ tall, above the top of the window, I pruned it back a few feet. Then, when it regrew, all the foliage was once again in the sun and at eye level.

African Violets

A healthy African violet.

African violets (Saintpaulia ionantha) are happy to stay in 4″ pots for years. Miniature African violets need smaller pots than that.

A rule of thumb for pot size and an African violet is to plant it in a pot that is 1/3 the spread of the foliage. So, a 4″ pot will accommodate a plant that is 12″ wide. Plants in top condition might take a slightly larger pot, but you have to pay very close attention to moisture and soil drainage.

“What should I do with an African violet that has a long trunk?”

As these plants grow new leaves from the top of the rosette, older leaves lower on the stem die off. That’s part of their natural growth pattern. When the plant develops a trunk, it’s time to make an adjustment. But don’t do this if the plant is slowing its growth. Spring to mid-summer is a better time for this procedure.

Remove the plant from its pot and slice off the bottom third of the root ball. Shave off a small amount from the sides as well. Wash the pot, check the plant for insects (mealybugs, especially), and treat with horticultural oil if necessary.

Place a small wad of polyester fiberfill (from a craft shop) over the hole. Add a small amount of African violet potting soil in the bottom of the pot. These plants like peat moss in their mix. Set the plant in the pot, and fill in the sides with more soil, using a chop stick to firm soil in the gap.

Part of the trunk will now be loosely covered with soil, and it will grow new roots. The top of the root ball should be lower in the pot than it grew previously. (Yes, this is exactly what we don’t ordinarily recommend.) Water it in, using lukewarm (about 85°F) water. Keeping the soil too wet will rot the trunk and the roots.

If needed, use the kitchen sink sprayer to wash soil off the leaves, using lukewarm water. Towel off the water drops, and let the plant dry in a warm location.

It’s less stressful for these plants if this is done every year or two, before the trunk grows a few inches tall. But I have seen perfectly happy violets with long stems curling over the edge of their pots.

“What are those marks on the leaves?”

Water the soil—always lukewarm for African violets—and avoid wetting the leaves. If water splashes on the leaves, absorb it with a towel, and let the plant dry in a warm place. As drops of water chill on this plant’s leaves, unsightly tan or brown rings and lines will be left behind.

Grow African violets at 70 to 74°, and fertilize regularly with a product formulated for this genus.

Less Is More

Move miniature species of plants into something only 1/2″ to 1″ larger, if they need it. I know; that doesn’t seem like it could make much of a difference. But for the plant whose roots, in the wild, might be crammed between layers of sedimentary rock on a blustery cliff, 1/2″ is plenty.

Large-growing plants require new pots up to 2″ wider in diameter. Peace lily (robust varieties of Spathiphyllum), weeping fig (Ficus benjamina), Chinese evergreen (Aglaonema spp.), and larger palm species can be moved from 6″ starter pots into 8″ pots. And, importantly, this assumes that the roots tightly fill the smaller pot.

Many of the tropicals will survive and prosper over the next several months, even while very potbound. If they’re already in 8″ pots, they’ll likely be fine until spring, when they can be potted on if needed. The 6′ tall fiddle-leaf fig in an 8″ nursery pot, though, can go into a 10″ pot, since the heated sunroom has floor-to-ceiling windows. Sunny conditions encourage plants to grow new roots, but carefully monitor soil moisture. Avoid watering houseplants (especially succulents) on cloudy days.

If growing conditions in your home are not ideal, but plants absolutely need to be repotted, transplant them now, before fall, into slightly larger pots. Wait until spring to transplant large houseplants, if it’s needed at all.

Houseplants don’t require repotting every year. Once they have attained a mature size, they no longer need to be moved into progressively larger pots. Instead, regularly fertilizing with products formulated for houseplants will supply all the nutrients they need.

Headings:

Page 1: Should We Transplant Houseplants Now?, Inspect Them First, Do Your Plants Actually Need Bigger Pots? (Fertilizing Houseplants, Fungus Gnats, Save the Spider!), When Should I Transplant Houseplants?, How Big Should the Pots Be? (The Old Weeping Fig, African Violets, Less Is More)

Page 2: Prepare for Transplant (Root Insects, Speaking of Spider Plants, Roots-Air-Water-Light) and Potting Up (Score the Root Ball, Potting Soil, Begin Filling the Pot, Downsizing, Water It In)

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Pages: 1 2

Annuals That Tolerate Heat, and Garden Tips

Jul3

2019

Annuals That Can Take the Heat

Happy 4th Of July!

Well, it looks as though the heat is on, as we celebrate our nation’s 243rd birthday. And summer just got started! Enjoy your Independence Day barbecues with family and friends, but don’t neglect the garden annuals and other potted plants. They’re going to need more frequent watering at these temperatures.

Here are some things we can do to mitigate problems that come with extreme heat, followed by a list of heat tolerant annuals.

Mulch the Beds

Mulching the gardens will keep annuals and shrub borders looking fresh all summer. Mulch serves several purposes:

it retains moisture in the soil
the soil stays cooler without the sun beating down on it
it helps prevent weeds from germinating
mulch helps prevent soil erosion
it prevents mud and dormant disease spores from splashing onto the plants
long term, it breaks down and adds organic matter to the soil
and it looks good

If bags of mulch have been hanging around for a while, gases can build up that might damage tender young annuals. So, open the bags and let the gases escape. I recall mulching newly planted alyssum many years ago, and by the next morning, they looked as if they’d been fried!

Sometimes, termites are found in old bags of hardwood mulch. Once the contents are spread around the gardens, though, the termites probably will die from exposure or due to separation from the colony.

Types of Mulch

Pine straw under a tree.

There are many kinds of mulch available from garden centers. I’ve always liked the look of dark brown shredded hardwood mulch. On a slope, it holds better than pine bark nuggets because the fibers interlock. Large quantities of shredded hardwood used repeatedly, however, can cause manganese toxicity and it can drive up the soil’s pH. Limit the depth to only 1″ in flower gardens or 2″ around shrubs and trees.

It’s a good idea to switch to a pine bark product for a few years to avoid these imbalances. Rhododendrons, azaleas, blueberries, hollies, and other acid-loving plants prefer pine products. But, if you want to use shredded hardwood around these plants, don’t pile it on and use an acidifying fertilizer.

Grass clippings break down quickly when used as a mulch by itself or under another mulch product. They contain some nitrogen, gently released as it decomposes. Use a very thin layer around your plants because it can heat up significantly as decomposition begins. But grass clippings can carry residue from weed killers and other chemicals used on the lawn, so maybe the best thing to do is to leave them on the lawn itself.

Pine bark nuggets can last a few years, but, if you’re a tidy gardener, you’ll have to blow away or pick out fallen leaves. It’s graded according to particle size, from pine fines, to small and large nuggets. Pine straw is new to me, since moving to North Carolina, but I still prefer shredded hardwood.

Mulch should not be piled high in the garden. Two inches suffices for most applications, although pine straw is applied more thickly. Keep it away from the stems and trunks of the plants.

Tree leaves that fall in autumn make a protective layer for garden plants, although many will blow around in high wind. This is more acceptable in rural areas or where the gardens aren’t open to public view. Most homeowner associations will find this free source of natural mulch objectionable. You could use a mulching mower to chop the leaves into smaller pieces, rake them into gardens, and cover with an inch of a more attractive mulch. Earthworms and decomposition will make them disappear.

Gravel In the Garden

I’ve never used gravel as a mulch around plants, except for potted lavender or succulent dish gardens. It settles into the mud, and “gravel travels” on an incline.

In certain circumstances, such as in the desert southwest and in dry rock gardens, gravel is a good choice. Around dry stream beds and in paths, gravel and rocks add natural elements, but should be laid over landscape fabric to prevent settling into the soil. If using gravel on the surface of a walkway, look for the kind with angular rather than rounded edges; it is less likely to sink underfoot.

Landscape Fabric

I am not a fan of using landscape fabric under mulched plants. This barrier interrupts the natural decomposition that occurs where the mulch meets the soil. Without the fabric, earthworms ingest the partially decomposed material next to the soil surface, and deposit fertile castings (excrement) into lower levels of soil, improving it in the process. This is how it works in nature, accompanied by thriving populations of various microbes.

Leaves, fallen trees, and dead insects and animals contribute to a healthy environment on the forest floor as they decompose. Microbes, earthworms, rain, and freeze-thaw cycles help distribute nutrients through the soil profile.

As the mulch breaks down over the fabric, weed seeds blowing into the beds will readily germinate in this rich medium. So, most gardeners using landscape fabric will be disappointed when they see those dandelions, plantains, and weedy maple trees taking root there. Mulch, with or without landscape fabric, doesn’t entirely prevent weeds, but it will greatly reduce their numbers.

Water the Garden Beds

Marigolds planted by volunteers in Arbourgate Meadows, Charlotte NC.

Make sure the flower beds and the shrubs, especially new ones, get a deep soak now and then if rain is scarce. Unless your area receives a prolonged period of rain, passing showers will moisten only the mulch. In most soils, 1″ to 2″ of water per week ensures that deeply growing roots will get their share.

Watering a little bit every day or two will not produce deeply rooted plants. Unfortunately, shallow roots are susceptible to stress from not only dry soil but also from hot soil.

It’s always best to water early in the morning, so the foliage is dry going into the night. This lessens the likelihood of diseases infecting annuals and other plants. Some of the water applied during the heat of mid-day will be wasted because of rapid evaporation. But if you’ve forgotten, and the plants are wilting, water as soon as possible, regardless of the time of day!

For busy families, watering with soaker hoses or tubes and emitters saves time. By placing the water directly on the soil, or under the mulch, very little is lost to evaporation. These systems can be attached to a computerized control center at the faucet. Just be doubly careful, though, when digging nearby, that the spade doesn’t land on the soaker hose. But if it does, there are repair kits for that.

The kids might enjoy a sprinkler or Slip ‘n’ Slide on a hot Fourth of July, especially the ones under 35. For a softer landing on the slippery strip, water the lawn underneath it first.

About the Hose

A garden hose kept in the sun will significantly heat the water inside it. Spray it out over the grass until it’s cool enough to apply to the gardens. Water under the canopy and beyond the drip line of the plants. Watering heavily as needed will cool the soil…for a while, anyway.

Water and Potting Soil

Caladium, variegated English ivy, and ‘Prizm’ impatiens, before impatiens downy mildew came along. The new ‘Imara’ impatiens is downy mildew resistant.

The trend in gardening over the years leans toward growing annuals in pots for key areas around the yard. Gardeners also are decreasing the square footage devoted to annual garden beds.

Container gardening requires vigilance, because soil in pots generally dries faster than garden soil. Hanging baskets filled with thirsty annuals and small blooming pots on the picnic table probably will need daily watering in areas with intense summer heat. For this reason, I prefer using larger pots when possible, such as 12″ to 18″ hanging baskets.

Strawberry jars introduce verticality and a unique appearance. Look for smaller varieties of plants to fill these containers.

Adding a thin layer of mulch to potted plants has the same advantages as mulching the garden. I use 1/2″ of pine fines, and sometimes shredded hardwood.

Amendments For Annuals

Potting soil with a high percentage of coarse drainage material, such as pine fines or perlite, tends to dry quickly. The soil doesn’t hold water, due to the large air pore space between the particles. Supplementing the potting soil with compost, peat moss, fine coir, or even some clean loamy topsoil from the garden adds more particle surface area where water can cling. You don’t want to create a heavy soil, though, that doesn’t drain well enough.

Planting mix, above, with high levels of pine fines, is best used to improve garden soil. Potting soil tends to have more finely textured materials.

When I lived in Maryland, Leaf-gro was readily available to amend potting soil and garden beds. I used tons of it! It was pure, rich compost, and was the end product of all that yard debris (weeds, grass, leaves) sent to the recycling center.

An additional benefit of using garden loam is the introduction of root-friendly microbes and micro nutrients, although you might have to pull a weed now and then. I can see you shaking your finger and warning of soil pathogens and worms…yes, true. If you’re concerned, you can buy bagged products that have been pasteurized. Ask to see the contents, though. The last bag of “sandy loam” I purchased contained mostly finely ground pine bark and sawdust.

Water-holding crystals are another option for potted plants and garden beds. Read directions carefully. Don’t add dry crystals to a pot; they need to be pre-moistened. I never found them to be that effective, but these new potting soils with all those pine fines might be improved with them.

Amending After the Fact

Supplementing bagged potting soil is becoming common practice for my pots these days. For the potted tomatoes that were drying too fast, I scratched about a gallon of clay loam from the vegetable garden into the top layer of soil in each 20″ pot. With each watering, the fine particles will sift down through the pot, filling some of the pore spaces.

It seems to have worked. The tomatoes aren’t beginning to wilt by mid afternoon after watering in the morning. And, on some days, I can even skip a watering. Much better.

Fertilizing Annuals

Heat-tolerant plants growing in pots will run out of fertilizer within just 2 to 4 weeks, depending on soil quality. Frequent watering and rainstorms leach nitrogen, in particular, through the soil. And, once nitrogen levels drop too low, older leaves will turn yellow, the plant might become pale overall, and growth will slow down. Nitrogen is the macronutrient that is needed in greater quantities than any of the other nutrients.

Each plant species is different. Some need more phosphorus or iron or magnesium. Check the label for a comprehensive list of ingredients.

Many annuals are particular about soil pH; some need acidic soil, while others tolerate a higher pH. At either end of the scale, certain nutrients become unavailable to plants. Most plants, however, grow well enough over a fairly broad range. But, if you notice yellowing, consider taking a soil test and having the chemistry analyzed.

Garden centers stock many kinds of fertilizers. They’re available as soluble crystals, dry granules, liquid concentrates, and as slow-release (or timed-release) prills.

Fast growing annuals need regular applications of nutrients. Rather than a feast-or-famine regimen, put the plants on a schedule so they never show the effects of “hidden hunger”. This and other good horticultural practices will keep your plants in prime condition until the end of the season.

Slow-Release Fertilizer

At high temperatures, slow-release fertilizer is consumed faster than the label might indicate. So, a 6-month product might be depleted after 4 months at 85°. Instead of simply placing the prills on the hot soil surface in a pot, dig a few small holes between plants, add the prills, and cover them with about an inch of soil. This will keep them cooler and prevent rapid release of the fertilizer.

In gardens, slow-release fertilizer can be placed under the mulch, scattered over the root zone. A small amount is released as water percolates through the medium.

Pot Colors

As these plants grow, they will shade part of the pots’ surfaces as summer temperatures rise.

Roots growing on the sunny side of dark pots, in hot summers, can heat to the point of death. So, most plants prefer light colored pots that reflect energy from the sun. If you really want to use the new rust-brown pots by the front door, add plants that trail over the side of the pot, shading enough of it to make a difference.

Another option is to use an insert, a plastic pot that sits inside the pretty pot, with space for hot air to escape. Maybe your beautiful teal pots can be tucked under the tree near the pool and planted with shade loving annuals.

This isn’t a concern in most parts of the country, but in southern states, the plants will appreciate this detail. Choose heat tolerant annuals that are less likely to be damaged by these conditions.

Winter Pots

Conversely, in chilly winter climates, dark pots absorb the sun’s warmth, delaying freezing of the soil. Find out if your pots will tolerate frost, and make sure they drain freely. “Frost resistant” does not mean “frost proof”.

When I potted large planters for customers’ winter gardens, I included sheets of styrofoam in the shoulders and on the sides of the pot, which absorbed the soil expansion as it froze. Pots with straight or sloping sides, with no curved shoulders, allow freezing soil to heave upward, usually avoiding breakage. In Maryland winters, expensive concrete pots were most likely to survive the cold.

Evaporative Cooling

Efflorescence on clay pots.

Most terra cotta pottery is porous, allowing air and water to pass through the sides of the pot. Some clay pots, though, are fired at higher temperatures, making them non-porous.

A clay pot with moist soil stays relatively cool, as moisture wicks through the pot. As water evaporates, the surface of the pot feels cooler. The same principle applies to perspiration evaporating from your skin. So, decorative clay pots in the summer are another alternative. But, they dry out faster because of the moisture loss through the pot.

The pots in the photograph have a white mineral coating called efflorescence. When fertilizer salts in solution migrate through the clay, they crystallize as the water evaporates. It can be removed or enjoyed.

Nursery-Grown Landscape Plants

Because containerized nursery plants are watered daily in warm weather, growers use a mix comprising mostly fast-draining pine fines, sand, and perlite, with some organic matter (peat moss, ground coir, compost) for water retention.

During hot summer weather, it is important to get transplants established as quickly as possible. New roots reluctantly grow into the native soil, but can be encouraged to do so by scoring the root ball or by teasing out some of the roots on the sides. This causes slight injury to the roots, and stimulates the plant to quickly form new side roots from the pericycle, a layer of cells inside the root.

Also, amending garden soil with organic matter, such as nutrient-rich compost, and pine fines for better drainage creates a welcoming habitat for new roots. Heavy clay soil is not very accommodating and hinders rapid rooting. You want to give your plants soil that drains well and entices roots to grow deeply. If you’ve ever tried to dig in dry, compacted clay soil, you know why plants are slow to establish. Good soil preparation makes a huge difference!

Why New Plants Sometimes Fail

A newly planted ‘Soft Touch’ holly, azalea, or autumn fern needs to have water replenished in the root ball every day in hot breezy weather. Until new roots expand into the soil, plants are entirely dependent on you for their daily dose. Make sure the water isn’t too hot.

I often consulted with homeowners when their new plants failed. When the shrubs were unearthed, their roots often were quite dry.

One landscape I visited here in Charlotte had very large evergreens newly planted in front of the house. All were dead or dying during a prolonged drought. After a little digging, I saw that 95% of the root system on each plant was bone dry because there was no organic matter mixed into the heavy clay soil. And only one irrigation emitter was placed on the side of the root ball. Each plant this size would have required a few emitters.

To make matters worse, the soil had been backfilled in large clods, and not broken up at all. Any water that flowed from the emitter drained right into the crevices, bypassing the root system. Those large air-filled gaps dried exposed roots even more. Any moisture in the root ball was quickly wicked away by the clay. This costly disaster illustrates the need for thorough soil preparation: breaking up heavy soils, incorporating amendments (drainage materials, organic matter) for improved tilth, and firming the soil around the root ball.

The problem is this…

…and it’s a point that doesn’t get a lot of attention. Water is sucked into the tiny spaces between clay particles by capillarity. And what’s abundant in soils throughout much of the country? Clay! So, when the shrub’s potting soil that is mostly pine fines (with large air pore spaces) sits next to native soil that’s composed of mostly clay (with tiny air pore spaces) what happens to the water? That’s right! It’s pulled from the shrub’s potting soil into the surrounding clay.

Clay always wins! This is one explanation for nursery plants that fail, even though the surrounding soil in the bed feels damp.

The remedy for a shrub with a high percentage of pine fines and perlite in the pot is to work some of the native clay into the root ball. Poke some holes a few inches deep (try using a dibble) on the surface of the root ball and fill with a few handfuls of clay or loamy clay; water it in.

This improves the water-holding capacity of the soil inside the root ball. Granted, this is a fine point. But the principle was effective for the potted tomatoes, mentioned in “Amending After the Fact”, above.

When Can I Plant?

Shrubs and trees establish in the landscape faster in autumn, when soil temperatures are still warm enough to promote root growth. Even in chilly soil, in the 40’s F, roots can grow. Air temperatures are more moderate then, and rain falls more predictably. The next best time is early to mid spring, as the soil begins to warm and before the trees leaf out.

But plants can settle into the landscape during the summer, too, as long as soil preparation was adequate and water is provided when needed. That ‘Jelena’ witch hazel would much rather be in the ground than sitting in a black pot at the nursery on this Independence Day.

Summer annuals root quickly, but give them enough water to prevent wilt. They’ll probably need water every day until their roots grow more extensively through the soil. And give them enough to moisten the entire root ball and the surrounding soil. It takes only one sunny 90° day to dry that new plant to a crisp!

Reservoirs and Saucers

Most hanging baskets and large plastic pots have a reservoir or an attached saucer at the bottom. It holds an inch or two of water that the plant’s soil will gradually absorb by capillarity.

It isn’t necessary to drain it off in the summer, if the plant is full of foliage. Any water the soil can’t absorb within 30 minutes, however, should be poured off.

For young plants and for succulents or plants that like dry soil, the reservoir or the saucer should be drained. Pour the excess water onto other plants instead of wasting the nutrients. Even worse is to let dissolved fertilizer wash down the street to the storm drain, eventually polluting the local creek.

Another option is to remove the saucer and allow water to drain freely into the flower beds or the shrub border.

Planting Wire Baskets

When I plant a wire basket, I line the inside of the coco liner with a “repurposed” sheet of plastic, such as an empty mulch bag. The plastic prevents evaporation through the coco liner, and slows decomposition of the coco liner.

Be sure to punch holes through the plastic in several places to allow drainage. But leave the bottom inch or so intact, forming a reservoir to hold water a bit longer, until it’s absorbed by the plants.

(For decades, as owner of Wellspring Garden, I never bought trash bags. I saved all the empty bags from potting soil, amendments, and mulch for that purpose. Using less plastic is the way to go!)

So, It’s Your Turn To Host the Party

A trip to the garden center reveals plenty of options to dress up the landscape for the holiday:

full grown, colorful blooming baskets for the deck or the porch
a potted combination “drop-in” worthy of that gorgeous ceramic container near the front door
some large annuals, in 6″ or 8″ pots, for the garden, looking as if they’d been growing there for months
a potted herb garden that guests can pinch to customize their salads (basil, chives, and others), and some mint ‘Julep’ or ‘Kentucky Colonel’ for iced tea, or other beverages.

Finally, string some lights for evening ambiance, and add red, white, and blue accents to celebrate Old Glory. Don’t forget to bring greenery into the powder room, in a pretty pot, adorned with a small flag.

Headings

Page 1: Happy 4th of July!, Mulch the Beds (Types of Mulch, Gravel In the Garden, Landscape Fabric), Water the Garden Beds (About the Hose), Water and Potting Soil (Amendments For Annuals, Amending After the Fact, Fertilizing Annuals, Slow-Release Fertilizer), Pot Colors (Winter Pots, Evaporative Cooling), Nursery-Grown Landscape Plants (Why New Plants Sometimes Fail, When Can I Plant?), Reservoirs and Saucers (Planting Wire Hanging Baskets), and So, It’s Your Turn To Host the Party

Page 2: Heat-Tolerant Annuals

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Grow a Potted Tomato: A Step-By-Step Guide

Apr8

How To Grow a Potted Tomato

Young tomato plants.

This year’s plan is to grow two potted tomato plants on the deck, inside the fence and away from deer. But less than a week ago, it snowed! For the near future, we’ll be having temperatures in the 70’s F, and in the 50’s at night. It’s time!

Judging by the numbers of people shopping at the garden centers, I’m not the only optimist out there. Always check your local forecast to see if it’s safe to plant tender edibles. Our friends in the North are still shoveling snow. Sorry, guys. Here are today’s purchases, and the step-by-step guide on page 2.

Tomatoes

Warm temperatures turn thoughts to tomato plants, so off to the garden center I went. Since we rarely buy tomatoes from the grocery store in the winter, we’ve been looking forward to this moment.

In one of the pots, I’ll include a young flat-leaf parsley and a sweet basil I bought at the grocery store a few weeks ago. The two herbs will be planted on the south side of the heirloom ‘Rutgers’ tomato, so they won’t be shaded. I’ll remove tomato leaves that interfere with the herbs. In case raccoons and squirrels set their sights on a lovely ripe fruit, bird netting wrapped around the fruiting plants will deter them.

Unfortunately, direct sunlight is decreasing in the vegetable garden, next to the house, as the trees to the south grow larger. Even so, the new ‘Sun Gold’ cherry tomato will go into the garden; if any tomato will produce a crop, ‘Sun Gold’ will. Besides, it did well enough last year. It produces loads of bright orange super sweet tomatoes, great for salads and snacking. Bet you can’t eat just one!

Basil

‘Tuscany’ basil.

The garden center also had ‘Tuscany’ basil, a light green lettuce-leaf type, with huge puckered leaves. It is wonderfully sweet and lightly spicy, with a hint of fresh anise flavor. ‘Genovese’ and lettuce-leaf basil are among my favorites for Tomato-Basil Salad.

And I added to the cart a pot of ‘Siam Queen’ Thai basil, for the baked salmon. Basil needs warmer temperatures, so they’ll stay in pots for a while, and come inside at night. Potted basil will come indoors even in summer, during rainy or humid weather. That’s when Basil downy mildew becomes a problem.

Curly parsley, a rogue seedling with last year’s flat-leaf parsley, and arugula survived the winter and still look good enough to hold onto for a while. The enclosed deck is a warmer microclimate, where winter temperatures are always higher than on the other side of the fence.

Although there’s some potting soil around, I’ll need more to fill those large pots and a few others. So, I bought the largest bag of soil the garden center carries. There’s enough packaged fertilizer left over from last year.

Caterpillars, Anyone?

I always keep a supply of Bt for battling the caterpillar invasions. Bacillus thuringiensis (Bt) is an organic alternative to substances I’d rather not consume, yet many people still consider it a “chemical”. It is not. Bt is a naturally occurring bacterium. An occasional spraying with Bt on the cole crops (kale, broccoli, cabbage, etc.) and on parsley and dill will save them from utter destruction!

The tobacco hornworm on a tomato leaf.

Sometimes, 1 or 2 tobacco hornworms attack our tomato plants. They look very similar to the tomato hornworm, which has V-shaped markings instead of the tobacco hornworm’s slashes (photo, above). They’re difficult to see because they blend so well with the foliage.

Left undisturbed, these larvae will develop into a type of hawk moth. But this very hungry caterpillar, as it grows, consumes large quantities of leaves, and leaves behind…well, you know what it leaves behind.

This nature nerd, as a young student, kept a tiny caterpillar indoors, and supplied daily rations of tomato leaves. Well, it grew enormous and wandered off to a secluded spot to pupate. My greatest fear was that my mother would find it. I finally found it, and donated it to a teacher’s Wardian case.

Spraying with Bt kills these hidden caterpillars if you can’t find them. It is more effective, however, when used on young caterpillars. But, if they have little things on their skin that look like grains of rice (photo, above), just pluck off the caterpillars and place them in the shrubs. A small female parasitic wasp laid eggs on or in the caterpillar, and the wasp larvae fed on and will soon kill the caterpillars. The “rice” grains are pupating wasps. And some little animal might appreciate a morsel such as this.

Big Pots

I bought two 7′ tall stakes and two 20″ diameter lime green pots, at first considered somewhat disagreeable, but now perfectly acceptable. This shade of green blends in with the greens and browns on the deck. When summer heat is a problem, light colors reflect some of the hot sun bearing down on the pots. This helps moderate soil temperature, which rises in a dark pot. Conversely, in the winter, black pots absorb warmth, keeping hardy herbs and cool season greens happy.

Discounted prices on vegetable transplants accomplished their intended effect: I bought more than I had planned. So, now there are 2 sweet peppers to plant, one a “green-to-red-when-ripe” bell, and the other a ‘Lunchbox’ orange.

Peppers

‘Lunchbox’ sweet peppers.

‘Lunchbox’ peppers are small and colorful (red, orange, or yellow—a separate color on each plant). I add them to omelets, salads, stir-fries, shrimp and vegetables with rice, and pizza.

They add great color accents as well as a higher vitamin C content than green peppers. In fact, one medium-large ripe lunchbox pepper has 100% of the RDA for Vitamin C.

It takes almost 3 weeks longer for a pepper to mature from the green stage to the colorful one. Normally, I would have waited a week or two for the pepper plants, but they were on sale…and it has been quite mild…

(“Weather Alert: severe thunderstorm watch, possible large hail, winds gusting to 60 miles per hour”. Time to move some things around outside.)

One More Tomato

The heirloom ‘Black Prince’ tomato is not as susceptible to cracking as some of the other black tomatoes. And the fruits are smaller. This one substitutes for the ‘Black Krim’ I was looking for.

If ‘Black Prince’ doesn’t do well enough, I’ll pull it out and plant something else. That’s one of the many advantages of living where the growing season is long. (***Update***: The ‘Black Prince’ has grown taller than the 7′ stake, and it is loaded with medium-sized fruits! I’ve already picked more than 20 richly flavored “black” tomatoes. Photo at end of Page 2. June 25, 2019)

And Zucchini

Zucchini with fruits.

The fourth of the four-for-$10 deal is a zucchini called ‘Black Beauty’. The seedlings have barely grown beyond the seed leaf stage, and they, with the basil, come indoors at night.

A 50-pound bag of aged cow manure rounded out the purchase.

I’ll plant the zucchini into a nursery pot, and later into the garden. But for now, the garden is still packed with cool season vegetables and greens.

Headings

Page 1: How To Grow a Potted Tomato, Tomatoes, Basil, Caterpillars, Anyone?, Big Pots (Peppers, One More Tomato, And Zucchini)

Page 2: A Step-By-Step Guide To Planting a Potted Tomato, Maintaining Your Potted Tomato, Temperature, Watering a Potted Tomato, Fertilizing a Potted Tomato, (How Often?, Blossom End Rot), Limiting the Suckers On Your Potted Tomato

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Vegetables in Containers: How To Grow Them

Jun17

2018

Updated 10/16/2024

No Garden Space? No Problem!

Growing Vegetables in Containers

Peppers and onions.

Before I started this blog, I managed the Edibles Department for a few years at an independent garden center in Charlotte, North Carolina. As some of our customers downsized to apartment living or to a condo with a balcony, they didn’t want to give up growing their own herbs and vegetables. So, they were glad to hear that they could grow vegetables in containers…as long as the balcony was on the right side of the building. And the right side for vegetables is the sunny side of the building.

Lack of direct sunlight and adequate growing space are limiting factors. Look around, though, and you might come up with some ideas. For example, some of our customers were given permission from their condo associations to garden in common areas. Running for open association board positions yourselves is one way to garner support. I encourage you to attend board meetings, bringing your neighbors, a plan, and a promise to maintain the site.

Neighborhood community gardens are another possibility, although there often is a waiting list. With so much emphasis on eating healthy foods, little pocket parks and community gardens are popping up all over the country.

For Your Convenience

A young tomato damaged by a squirrel.

Another reason to grow vegetables in containers is simply to have them close at hand when they’re needed. A few steps out the kitchen door to a handful of cherry tomatoes and a ripe ‘Flavorburst’ sweet pepper for today’s salad has its charms.

Keeping the pots elevated on the deck prevents some animals, such as deer and rabbits, from making off with the fruits of your labor. Won’t stop the raccoons, though. (***Update***: Or the squirrels; one thought this little green tomato had something to offer. Discard any fruits that have been chewed on by animals. If needed, I’ll wrap the potted tomato plants, growing on the deck, in bird netting. June, 2019.)

Sun? Not So Much

The choices for edibles in a shady spot are limited. The ones that might succeed in bright shade are arugula, cilantro, parsley, lemon balm (interesting research with Alzheimer’s), French sorrel, and seasonal leafy greens. With just a bit more sun, basil, rosemary, oregano, and maybe a cucumber plant could grow for you.

Reflected light counts, to a degree, including light bouncing off light-colored walls. And a white surface under the pots reflects more light onto the vegetables in containers.

Remember to monitor the sun’s path throughout the seasons. Once trees drop their leaves in the fall, your balcony or patio might receive more direct sunlight than it did in the summer. This opens up all kinds of possibilities for potted cool-season greens and vegetables. Pay close attention to expected temperature changes for the duration of your crops.

Fruiting plants, such as tomatoes, peppers, eggplants, and squash need at least 6, and preferably 7 or 8 hours of direct sun. These vegetables also need warm summery weather.

Approaching Summer Solstice

Our vegetable garden is now receiving the maximum amount of light, with the sun directly overhead. In the springtime of the last two years, heavy rains caused the tree canopy up on the berm, to the south, to swell with heavy, overhanging branches. Trees now cast considerable shade early and late in the day for most of the growing season. So, I planted fewer tomato plants and more greens.

Two large ‘Big Beef’ tomatoes are beginning to ripen, and a whole lot of ‘Sun Gold’ and ‘Mexico Midget’ cherry tomatoes. So, even with less-than-ideal conditions, there will be something to harvest.

At Julia’s Request

Several family members from New Jersey and California recently visited us in North Carolina. I promised Julia this article about growing summer vegetables in containers.

Vegetables In Containers: Which Ones?

: Potted green onions.

: Potted tomato.

Sweet and hot peppers, tomatoes, and eggplants can be grown in containers, as well as zucchini, yellow summer and Patty Pan squashes, cucumbers, and green beans. Also, it’s easy to grow most herbs in pots. Green onions, carrots, potatoes, and peas can grow in pots!

It’s just a matter of the details. One of those details is to look for dwarf or bush varieties of the crops you want to grow. There’s even a variety of corn (‘On Deck’) that grows in large pots.

One of the popular combinations I used to sell included a sweet or a hot pepper planted with two herbs. Theme combinations (‘Jalapeño’ pepper/cilantro/Greek oregano; ‘Carmen’ frying pepper/Italian parsley/Italian oregano) grew in 14″ pots. Customers found them irresistible if they were bearing fruit.

Growing more varieties of leafy greens in containers has become a priority as our garden becomes more shaded. In addition, greens can grow all year in regions with moderate winters.

Starting With Tomatoes

Much of the information in “Starting With Tomatoes” also applies to other vegetables in containers.

Potted ‘Indigo Blue Berries’ cherry tomato ripens to orange and black.

Beginning with America’s favorite, tomatoes grow well in pots. Will it be a beefsteak or a cherry? An heirloom or a modern hybrid? A slicer or a sauce-type? Determinate? Indeterminate (it keeps growing until frost, bearing fruit all summer)? Black, red, yellow, or orange? Striped or solid? There are many thousands of varieties of tomatoes to choose from!

‘Terenzo’ tomato.

A dwarf tomato called ‘Terenzo’ (photo, right) can grow in a 10″ hanging basket, but a ‘Cherokee Purple’ heirloom or a ‘Big Beef’ needs something considerably larger. For the large varieties, I use pots at least 20″ in diameter.

The long-vining indeterminate cherry types (‘Sun Gold’, ‘Black Cherry’, ‘Mexico Midget’) can grow in a pot as small as 14″ in diameter, but they’d be happier in bigger pots. You’ll need to pay closer attention to water and fertility when using smaller pots.

Vegetables In Containers: Types Of Pots

Each kind of pot has both advantages and disadvantages.

Summer vegetables generally fare better in larger pots rather than smaller pots. Although the pot looks enormous compared to the transplant’s diminutive size, don’t be tempted to plant more than one tomato per pot.

You’ll be amazed how quickly that one tomato plant fills a 20″ pot. A new transplant in a large pot runs a greater risk of root rot during rainy weather. But, placing it under an overhang will prevent this loss. It’ll be different once more roots and foliage have grown.

An indeterminate tomato, such as ‘Cherokee Purple’, ‘Sun Gold’, or ‘Black Krim’, can share a 20″ diameter pot (photo, below) with a couple of herbs, such as parsley and oregano. Plant the tomato toward the back of the pot, on the north side (northern hemisphere), and plant the herbs near the southern rim.

Terra Cotta

Terra cotta looks good and has some weight. But clay is porous, so water vapor passes through the pot to the air outside, quickly drying the soil. If you want to use your large clay pots, you could line them with food-grade plastic and punch some holes in the bottom for drainage. This will slow down the evaporation process.

Certainly, use clay pots if you prefer, but prepare to water more often.

Ceramic Pots

Ceramics are beautiful and heavy, and they can be expensive. Soil temperature rises uncomfortably on the sunny side unless the pot is shaded. Try using light colored pots in the summer, which will reflect most of the heat.

If you’re unsure of the safety of the glaze, line the inside of the pot with food-grade plastic bags, poking several holes in the bottom for drainage. Choose a different pot if a sticker on the bottom warns “Not for direct contact with food”.

You could also plant the tomato in a large nursery pot, and then insert it into the decorative glazed container. Make sure both pots have drainage holes. This “double-potting” allows air circulation around the interior pot and eliminates concerns about questionable glazes.

Tomato ‘Rutgers’, sweet basil, and Italian parsley in a 20″ wide pot, April, 2019.

Plastic and Vinyl

These pots are inexpensive, readily available, and easily moved. They’re also the most likely to blow over in windy weather. But this is the first choice for most gardeners. Most of these pots last a few to several years in the sun, but, eventually, sunlight will degrade the material.

Wood Containers

Untreated cedar or redwood and half whiskey barrels are suitable for growing vegetables in containers. Check to make sure the pots drain freely.

Reservoirs and Other Considerations

Earth boxes and plastic pots often have built-in reservoirs or detachable saucers. And you can purchase caster kits and trellises for increased functionality. Some gardeners have the option to move their plants from the morning sun on one side of the deck to the afternoon sun on the other side; wheels make this so much easier.

Caution: some of the reservoirs are too deep before the water begins to exit the overflow hole. This can cause young plants to rot if the soil stays sodden all the time. You could drill a hole in the side, below the overflow hole, reducing the capacity of the reservoir. Or simply tilt the pot to allow excess water to drain. Older plants, full of foliage, will absorb water in the bottom of the planter, as long as it isn’t raining for several days straight.

Mosquitoes and Tree Roots

Add a piece of Mosquito Dunks to prevent mosquitoes from maturing in the secluded reservoir. They need only a few days in warm weather to complete their life cycle. Or tip the container to drain all excess water.

A pot sitting directly on soil anywhere near trees or shrubs will invite their roots to invade. Believe me, they will try to grow in that beautiful composted soil. Elevate the pot off the ground. This also facilitates drainage from the pot.

A few pieces of broken flagstone or “pot feet” raise the pots above the surface of the deck, helping to preserve the deck’s finish.

Saucers

Use saucers under the pots, but don’t let water remain in them for more than an hour. Plant roots need oxygen as much as they need water. Water in the saucer prevents air from entering the bottom of the pot.

Saucers aren’t absolutely necessary, but help if the soil has gone too dry. Just keep filling them until no more water is absorbed by the soil. In tall pots, though, the force of gravity will prevail over capillary action, preventing water from reaching the top of the root ball. So, you’ll also need to water the top portion of soil.

During long periods of rainy weather, I remove the saucers, or turn them upside down and keep them under the containers. This is impractical, however, if the pot weighs 50 pounds. Consider removing the saucer and using a few pieces of broken flagstone or brick to elevate the pots, if necessary.

Potting Soil

Reused polyester fiberfill covers the drainage hole.

Before filling the pot, place a small handful of polyester fiberfill (from a hobby store) over the drainage hole. This prevents soil from eroding through the hole, and prevents earthworms and other critters from entering. If you pull some of it through the hole to a point at the bottom, excess water will continue to drain if there’s soil in the little cone. This is helpful for potted plants that rot easily during long stretches of rainy weather (succulents, lavender, thyme, sage). This synthetic material doesn’t rot, so it’s reusable.

Use a good quality potting soil that drains well, but has peat moss to hold moisture. In addition to the peat moss, the mixture will have perlite (white particles that help drainage), pine bark chips (drainage), lime (to adjust the pH), compost or a starter charge of fertilizer, and often a wetting agent (to help the soil absorb water).

Amending the Potting Soil

Feel free to experiment with mixtures of different materials. Soils with a lot of bark (pine fines, wood products) in the mix tend to dry out faster. You can mix in smaller-particle loamy topsoil, spongy peat moss, aged manure, or compost to help slow water loss. Water-absorbing crystals might help, too. But moisten them before you add them to the soil. If you don’t, you’ll understand why I italicized the word “before”.

Adding a layer of undyed mulch on top of the soil helps conserve water and keeps the soil a bit cooler.

While some gardeners add rocks to the bottom of the pot, I never do. It was thought the rocks increased drainage, but the opposite is true; they create a perched water table in the layer of soil right above the rocks. Water percolating through the soil profile is held in this layer by capillarity, and often rots roots trying to grow there, limiting the useful volume of soil.

Headings

Page 1: Growing Vegetables In Containers, Sun? Not So Much, Vegetables In Containers: Which Ones?, and Starting With Tomatoes (Vegetables In Containers: Types Of Pots, Reservoirs and Other Considerations, Mosquitoes and Tree Roots, Saucers, Potting Soil (Amending the Potting Soil)…

Page 2: Transplanting the Tomato, Water, Going Away?, Staking, Fertilizing Vegetables In Containers, Blossom End Rot, On PH, Pollination), Peppers and Eggplants, Cucumbers, Squash (Squash Vine Borers), Green Onions (Bunching Onions from Seed), Leafy Greens, and Picking Vegetables In Containers

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