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How To Grow Potatoes In 5 Simple Steps

Can we grow new potatoes from old potatoes?

grow potatoes

Yes!

So… those potatoes left in the pantry or the bottom of the refrigerator decided to sprout. Instead of throwing them into the trash or the compost bin, try growing them! You can grow potatoes in the home garden or in large pots, following a few simple guidelines.

Too withered for consumption, but fine for the garden.

We don’t recommend planting potatoes recently purchased from the grocery store because they’ve likely been treated with a sprout inhibitor. After the effect wears off, you’ll see the eyes begin growing. That, though, could take months.

Organic potatoes, if treated with sprout suppressors approved by the National Organic Program, sprout earlier than non-organic potatoes. Inhibitors, such as spearmint, peppermint, and clove oils, must be applied more frequently than chemicals used on traditionally treated potatoes.

Spouting potatoes (like the ‘Yukon Gold’ in photo, top) are still edible, after removing the eyes. Discard moldy and rotting potatoes. But save for the garden the ones with well-developed sprouts and those that have withered beyond the point of palatability.

Carbohydrates stored in the tuber provide energy for the developing shoots. When green leaves begin growing, photosynthesis will sustain the plant.

When can we grow potatoes outside?

Potatoes can tolerate cool soil, but not cold, wet soil or freezing temperatures. I live in USDA plant hardiness zone 7, where we plant early maturing varieties 4-6 weeks before the last spring frost. Gardeners plant mid-season and late varieties after that.

Wait for the soil to warm up to at least 45°F before planting tubers. Long-range weather forecasts might indicate whether it’s safe to plant or prudent to delay.

A garden exposed to full direct sunlight warms up earlier in spring than one in partial sun. Grow potatoes in full sun, but avoid exposing them to searing summer heat. Gardeners living in higher elevations or in cooler summer regions can grow potatoes through the season.

If the weather forecast predicts temperatures below freezing, I’ll mulch the soil with several inches of oak leaves, never in short supply around here. A thick, airy mulch insulates the ground from a sudden drop in temperature. Plants benefit from mulch kept in place all season. Not only does it moderate temperature, suppress weeds, and keep moisture in the ground, but it also prevents disease spores from splashing onto the potato’s leaves. This is easier to do in small garden plots than in larger farming operations.

Emerging foliage can tolerate light frost. It could take a few weeks for growth to show above ground.

Seed Potatoes

For a wider selection of varieties offered to farmers and home gardeners, look for “seed potatoes”. Some garden centers and many seed suppliers stock seed potatoes. They’re not actually seeds, but certified young potatoes almost ready for planting. Although they’re certified disease-free when purchased, plants are susceptible to a few pathogens as they grow.

Favorable conditions and good management practices decrease the likelihood of problems. If you’ve had diseases in your potato crops, don’t save potatoes year to year, but purchase certified potatoes instead. Don’t grow potatoes where they’ve been planted any time in the past 4 years.

Botanically speaking, potatoes are classified as Solanum tuberosum. They belong to the Solanaceae family and call tomatoes, peppers, and eggplants their cousins. Tobacco, petunias, and deadly nightshade, a poisonous weed, also belong to the nightshade family.

Potatoes are native to the cool mountainous regions of South America. In the 1530’s, European explorers gathered them and introduced potatoes to their homeland. Irish immigrants brought them to North America in the early 1700’s. Approximately 4,000 varieties of potatoes have been bred. True seeds, as opposed to seed potatoes, are poisonous when eaten and are used only for breeding purposes.

You can find potatoes with white, yellow, tan, red, blue, and purple skins and flesh. Thin-skinned potatoes, such as ‘Yukon Gold’, ‘Kennebec’, and ‘Red Pontiac’, grow well in the eastern parts of the U.S. The western states suit the thicker-skinned ‘Russet’ and other baking potatoes.

Crop Rotation

One of those good management practices involves rotating our crops. Related plants tend to be susceptible to the same pathogens and insect pests. When growing one crop in the same plot of land year after year, disease spores and insects can build up in that location. That’s why it’s recommended to move all members of a particular plant family to different plots over the next several growing seasons.

For example, if you grew potatoes, tomatoes, peppers, or eggplants in Plot A in any of the last 4 years, move your potatoes and other members of the Solanaceae family to Plot B this year, Plot C next year, and then Plot D the year after that.

Rotate among the various plant families, such as:

brassicas—arugula, broccoli, Brussels sprouts, cabbage, cauliflower, kale, etc., in the Brassicaceae family
cucurbits—cucumber, squash, zucchini, melons, in the Cucurbitaceae family
legumes—peas, beans, in the Fabaceae family
lettuces, in the Asteraceae family
onions, leeks, garlic, in the Amaryllidaceae family
Swiss chard, spinach, beets, in the Amaranthaceae family

Several varieties of potatoes.

How To Grow Potatoes In the Garden

Step 1: The First Cut

Before planting potatoes in the ground, cut them into pieces about 1½” long. Each piece should have 2-3 eyes. Let them sit in the open air for 1-2 days to seal the cut surface. This helps prevent rot in moist soil.

Small potatoes can be planted whole.

Step 2: Prepare the Soil If You Want To Grow Potatoes

Thorough soil preparation serves the immediate purpose as well as plantings in years to come. After improving the soil with generous amounts of drainage materials, you’ll need to add nutrient-rich amendments a few times each year after that.

Not repeatedly disturbing the soil profile retains healthy populations of beneficial microbes. Farmers are increasingly using no-till methods and cover crops to preserve soil structure and prevent erosion of valuable topsoil. Frequent tilling also introduces high levels of oxygen between the particles of soil, so organic matter is broken down too quickly.

Vegetable plants need good drainage, and potatoes are no exception. Loosen the soil at least 12″ deep, breaking up the clods. Potatoes struggle in compacted clay and stony soils; tubers that do form are often misshapen. Potatoes grow very well in raised beds.

Incorporate a few inches of pine fines, soil conditioner, peat moss, and/or coarse sand to improve the tilth (or workability) of the soil. Avoid layering materials in the soil profile. Layers of coarse and fine materials, with differing air pore spaces from one material to another, obstruct water percolating through the soil. This could cause soggy layers that can rot roots. For that reason, I never place a layer of gravel under plantings.

In the top 5″ of loosened soil, mix in compost, leaf mold, or planting mixes. These materials contain a variety of nutrients required by vegetables, and they encourage rapid rooting.

Aged manure and mushroom compost are not recommended for root vegetables.

Soil PH

Potatoes love heavily composted soil. They also require acidic soil, with a pH between 5.0 and 6.0. (Various websites recommend a pH anywhere between 4.8 and 7.0.)

Low pH helps prevent scab, a disfiguring disease of potato skins. Soil pH outside the preferred range for potatoes limits nutrient absorption and might cause nutrient toxicities.

Contact your local agricultural extension agents for information on taking a soil test. They can recommend preferred fertilizers, methods to lower soil pH, and varieties appropriate for your area.

Step 3: Place the Seed Potatoes

In rich, organic soil, simply lay the potato pieces on top of moist, loosened soil or nestle them into the surface. The eyes should face upward. Then mulch over the seed potatoes.

They’ll also grow when planted 2″ deep. Space potatoes 6-12″ apart, depending on variety. Because potato plants grow 2-3′ tall and might sprawl a bit, allow 30-36″ between rows.

Mulch the bed with a few inches of leaf litter, shredded leaves, and pine needles to cover the planted potatoes. It’s important to adequately shade the surface of the ground from sunlight to protect growing tubers from greening…

“Greening”?

Potatoes with green skin needed deeper mulch.

Greening is caused by exposure to light, which, in itself, is not harmful. But the green pigment (chlorophyll) in potatoes is associated with the formation of a toxic glycoalkaloid called solanine.

Never eat green potatoes; if only the skin is green, cut off and discard that part before cooking. Never eat leaves, stems, or the berries that develop on potato plants.

Solanine in potatoes is more concentrated when growing potatoes in high nitrogen soils and in soil that’s compacted or very sandy. Bruised potatoes, those held a long time in storage, and potatoes with large eyes are higher in this toxin. The greener the potato, the higher the level of solanine. This bitter substance is a natural repellent to insects and browsing animals.

Solanine can’t be boiled or cooked away. The level is somewhat lower in foods fried at very high temperatures, but that brings its own problems, described later in this article. I’m not intent on discouraging you from growing or eating potatoes, but moderate consumption of this popular vegetable and proper preparation make it a healthier indulgence.

Symptoms of solanine toxicity include vomiting, diarrhea, slow pulse or breathing, low blood pressure, and abdominal pain. It can cause coma and death in rare instances, so be very careful with green potatoes. If any of the flesh is green after removing the skin, I would discard the potato.

Step 4: Maintenance

Water

Water the garden thoroughly after planting and mulching. If rain is unreliable, water the garden every week, never letting the soil become dry. Provide 1-1½” of water each week if it doesn’t rain.

Avoid wetting the foliage, and water in the morning so the foliage is dry going into the night. This helps cut down on the incidence of disease. Some varieties are resistant to blight, scab, Rhizoctonia, and Verticillium wilt. Those that have not been bred with disease resistance often produce great yields when using good gardening practices.

Hollow Heart and Brown Center

Some large varieties, particularly ‘Atlantic’ (for potato chips) and ‘Yukon Gold’ (a personal favorite), might show hollow heart and/or brown center. These are physiological disorders characterized by a star-shaped cavity and a central area with dead brown tissue, respectively, in the center of the potato or near the ends.

These stress-related conditions often result from inconsistent soil moisture—for example, wet soil after a period of dry soil. In addition, a period of prolonged cold weather during tuber formation can cause brown center. Spacing seed potatoes too far apart and using small seed potatoes (with too few eyes) can be the cause. Low potassium and other nutrient deficiencies can initiate the disorders.

The potato’s skin shows no indication of a problem. Affected potatoes aren’t perfect but are still edible.

Hilling Up

As the plants grow, hill up soil against the stems of the plants. Take soil from another part of the garden, adding a few inches up the stem and about 12″ out from it. This is an option—not necessary—but it should increase the yield.

Like tomatoes, potatoes root along buried stems. As they root, they’ll develop another layer of young potatoes at the ends of the stolons. Hill up around the stems 2 or 3 times during the growing season to maximize the harvest.

An alternative is to start potatoes in a moderately deep trench, reserving excavated soil on the side of the bed. Periodically fill in the trench with amended soil, a few inches at a time.

Fertilizer

Every few weeks, apply a complete fertilizer. The 3 numbers on the package representing nitrogen, phosphorus, and potassium (N-P-K) should be in a ratio of 1:1:1 or 1:2:2. Avoid fertilizers high in nitrogen. An analysis close to 10-10-10 or 5-10-10 is adequate.

Although you could use chemical fertilizers, they tend to damage populations of beneficial microbes. But, until the soil warms up, microbes aren’t sufficiently active to break down the organic components into molecules the plants can absorb. That’s when I use chemical fertilizers, and then switch to organic products when the soil warms.

To help prevent disorders in developing potatoes, it’s recommended to apply smaller concentrations of fertilizer more frequently.

Insect Pests

Colorado potato beetles can be especially bothersome as they consume significant amounts of foliage. Inspect the undersides of the leaves for yellow-orange egg masses and remove them. The beetles have 10 black stripes on their tan wings. Immature larvae are orangish-red with 2 rows of black dots down each side. Bacillus thuringiensis var. tenebrionis, a biological insecticide, kills this beetle.

Aphids might congregate in large numbers on the plants. A brisk spray of cool water from the hose takes care of most of them. Encourage ladybugs, braconid wasps, and green lacewings to populate your garden. For severe infestations, prepare a solution of horticultural oil and spray early in the morning. Apply the solution to the bottoms of the leaves as well. Read the label.

Cutworms feed on sprouts emerging from the ground. Since these C-shaped larvae become moths, treating the potatoes with Bacillus thuringiensis var. kurstaki effectively kills them. Keep in mind that they’ll have to eat some of the foliage in order to ingest the Bt.

Slugs and Deer

A slug.

Slugs reproduce rapidly in moist conditions and where they can hide in crevices during the daytime.

Lay a board on moist ground, and slugs and snails will gather there after feeding through the night. You might notice those silvery slime trails on tender foliage. Early in the morning, take an old knife to the garden and… dispatch them forthwith! Or use organic Sluggo or similar product, which does not contain toxic chemicals. Except to slugs and snails. Read the label.

Although potato foliage is not the favorite choice of warm-blooded animals, deer and others will feed on it when not much else is available.

Other members of the nightshade family also host these pests. Row cover secured over the planting excludes most insects and browsing animals.

Potatoes that sprouted in storage are now growing new plants in 6″ pots. They’ll need protection from hard frost if planted, but I didn’t want to delay planting the deteriorating tubers.

Headings

Page 1: Can we grow new potatoes from old potatoes? (When can we grow potatoes outside?, Seed Potatoes, Crop Rotation), How To Grow Potatoes In the Garden, Step 1: The First Cut, Step 2: Prepare the Soil If You Want To Grow Potatoes (Soil PH), Step 3: Place the Seed Potatoes (“Greening”?), Step 4: Maintenance (Water, Hollow Heart and Brown Center, Hilling Up, Fertilizer, Insect Pests, Slugs and Deer)

Page 2: Step 5: Harvesting!, How To Grow Potatoes In Containers, Grow Potatoes For Their Nutrients (The Power Of the Purples, Potato Skins, Resistant Starch), The Problem With High Heat

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Soil Prep 101 For Your Vegetable Garden

Apr25

Cool season vegetables and greens.

Finding the Perfect Spot for Your Vegetable Garden

For the purpose of this post, I’ll assume that your vegetable garden will be flush with the surrounding lawn, rather than in a raised bed. However, sound horticultural principles apply to either method. Locate the garden where it gets lots of direct sunlight, and avoid low areas that collect water after heavy rain. Place it close to a source of water.

Now that you’ve found the perfect spot for your vegetable garden, you’re ready for Soil Prep 101. The types of crops you plant in any season are weather-dependent, so make sure weather patterns in your location suit the peppers, basil, kale, or cauliflower.

Although this article concentrates on preparing beds for vegetable gardens, the principles apply to other plants as well, including new shrub borders and flower gardens for pollinators. Page 2 of this article has tips for improving the soil’s tilth, or workability, for most garden projects.

Prerequisites for this class: “How to Prepare the Soil: An Introduction” and “Yes, But Is It Sunny In the Winter?”

Swiss chard in a raised vegetable garden

Swiss chard in a raised bed.

Depending on your level of affinity for precise measurement, you can use either a measuring tape or simple paces to mark the dimensions of your garden. Gardeners who want to indulge in culinary experimentation by growing a wide variety of crops might regret not having made the vegetable garden large enough from the outset. Consider the possibility of expansion in the future.

How Much Sun Does the Vegetable Garden Need?

There is no substitute for sunlight. Without at least 6 hours of direct sun, the results will be disappointing. Anything less than that will reduce and delay the harvest.

Indirect, dappled, and filtered light don’t really count. In fact, during most of the growing season, fruiting plants perform so much better with 7 or 8 hours of sun, minimum! There are other types of crops that can be grown in less than full sun, including leafy greens (lettuce, arugula) and a few herbs (cilantro, parsley).

Layout

Tomato.

Someone out there is asking, “Do I run the rows (the long axes) east-to-west or south-to-north?” Good question! If your plans include growing several tomato plants and maybe some pole beans on a trellis, and you prefer one long plot that is accessible from both sides, I recommend east-to-west.

Long-term plants (tomatoes, peppers, etc.) will continue to get good sunlight all season. Spaced properly, they won’t cast as much shade on each other, especially as fall approaches and the sun sinks lower in the sky. But, if your garden receives sun all day, it won’t make much difference to main season crops.

Cool season crops, grown from fall through early spring, however, will get more sun when planted east-to-west. They’ll face the sun all day even though the days are short.

Taller plants should be planted on the north side of any plot (northern hemisphere), so they don’t shade smaller plants nearby. Some varieties of staked indeterminate tomatoes can grow 8′ tall!

lettuce basket, a portable vegetable garden

Lettuce growing in a basket.

On properties where spatial considerations are limited, do what you can to provide enough direct sun to those crops you can’t live without. Your crops might not be lined up in neat rows, but rather planted individually in a sunny corner over here and another by the back gate. Doesn’t matter. Do what works for you!

Container-grown crops, such as this lettuce basket (photo, above), can be moved around as conditions change.

Multiple Vegetable Garden Beds

With ample space, a series of garden beds can be laid out in a grid. When deciding where the plants will go, always keep in mind that you want to prevent tall plants from shading short plants, with few exceptions. Using straight pathways makes maneuvering the wheelbarrow and equipment easier.

Crops that prefer cooler, part-shade conditions as the weather warms can be planted between the taller plants or in the partial shade they cast. Those include late spring lettuces, arugula, cilantro, and spinach.

Savoy cabbage.

Having several plots allows for crop rotation, planting one family of plants in Plot A this year, in Plot B next year, and so on. This helps prevent the soil from being severely depleted of certain micronutrients and from allowing populations of insects and diseases to build up.

The nightshade family (Solanaceae: tomato, pepper, eggplant, potato), the cucurbits (Cucurbitaceae: cucumber, summer squash, zucchini, melon, pumpkin), and the brassicas (Brassicaceae: broccoli, cabbage, cauliflower, kale, Brussels sprouts) are groups of plants that benefit from being rotated every 4 or more years.

To clarify, one member of a family (tomato, for example) should not be planted where any member of that family (tomato, pepper, eggplant, potato) has grown in the past few years.

This is a good reason to keep a record describing where you plant each crop every year, as well as documenting successes and losses. Knowing the family names that crops belong to also helps with crop rotation.

Seed Or Transplant?

Don’t go overboard if this is your first attempt. You’re not obligated to germinate every pack of seeds you bought. There’s always next season. Most seeds will remain viable for a few years if kept dry and cool.

Starting out with young tomato, pepper, or slow-growing parsley transplants might be more practical than growing them from seed, even though it is more expensive. You’ll find them at garden centers, farmers’ markets, and local hardware stores, and the growers often have good suggestions for cultivation.

If you’re late getting the vegetable garden going, transplants will save you several weeks of growing time. You can always supplement with fast sprouting varieties of seeds, such as those mentioned in the next section.

Starting plants from seed is a welcome challenge to many and is a source of fascination for children—and for adults, too. Don’t laugh, but, for me, it’s a thrill when the catalogs start showing up in the mailbox. I would never discourage you from exploring this facet of gardening. And, of course, there are so many excellent varieties available from seed that never show up in retail stores as transplants.

Seedlings For Vegetable Gardens Need Sun

Seedlings of fruiting crops need at least 6-8 hours of direct sunlight for strong growth. Use clean pots, pasteurized seed starting mix, and a waterproof tray. Provide the proper temperature for germination.

If you don’t have very sunny windows or a greenhouse, consider starting seeds under shop lights with daylight tubes. I use 4′ long fixtures that hold 2 tubes each. Seedlings growing very close to the tubes—only a few inches away—grow strong stems and roots.

Lettuces, arugula, and other leafy greens tolerate fewer hours of sun, although they appreciate full sun during the cooler months.

Avoid starting seeds too early in the season. This could result in leggy, weak plants that might not perform up to par in the garden.

Broccoli ‘Happy Rich’ and Arugula ‘Astro’ seeded into cell packs (late winter, 2022).

Seeding Directly Into the Garden

Some crops grow easily from seed sown directly into the vegetable garden. Peas and beans, for example, and radishes, beets, and carrots are just a few species that can be planted right into prepared ground. Dinosaur kale, mustard spinach, mesclun, leaf lettuce mixes, zucchini, spinach, and cucumbers are more crops that can be directly seeded.

Read all the information on the packet, paying special attention to when to start and how deeply to sow the seeds. Although these crops germinate readily, gardeners must still watch out for pests, both above and below ground, and turns in the weather.

Spacing the Plants

It’s important to calculate how much square footage each of your plants requires, or at least to get a rough idea. On graph paper, map the proposed garden to scale. Use the plants’ spacing recommendations found on the label or the seed packet for the amount of space needed.

With a 1/4″ grid, each square can represent 6″ or 12″ of garden space. The diagram is optional, but it can help in future years when considering crop rotation.

It’s better to have more than enough room rather than not enough; plants don’t respond well to crowding. The seemingly large gaps between the major crops can be interplanted with “ephemerals”—those plants that grow quickly and are harvested before the majors achieve full size. Examples include radishes and lettuce between tomato plants, or green onions and beets between autumn-grown Brussels sprouts.

If It Looks Like This…

Clay soil shrinks as it dries, creating surface cracking.

Soil that dries as hard as a brick is impossible to work with. You can thoroughly water the area the day before or start digging a day or two after a good rain. Avoid digging or walking in the garden when the soil is wet. This compresses the soil, squeezing out tiny channels of air space that are critical for healthy root growth.

Sandy soil that drains too fast should be amended with copious amounts of organic matter. Bagged topsoil is also available, but quality varies widely. The tiny clay particles in clay loam help hold water and nutrients in the soil.

In a large vegetable garden, plan for pathways every 4′ or 5′, and restrict foot traffic to those areas. Use pavers, flagstones, pine bark, or even that old pile of bricks for the pathways. You can get very creative with stonework, and your garden can be the neighborhood show-stopper, but don’t lay out the stones until the end of the soil prep process.

Let’s begin! Please turn the page…

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Headings

Page 1: Finding the Perfect Spot for Your Vegetable Garden, How Much Sun Does the Vegetable Garden Need?, Layout, Multiple Vegetable Garden Beds, Seed Or Transplant? (Seedlings For Vegetable Gardens Need Sun, Seeding Directly Into the Garden), Spacing the Plants, and If It Looks Like This…

Page 2: Remove Sod, Tilth, Soil Prep (The First Dig: Loosen the Clay, The Second Dig: Add Drainage Materials, Organic Matter vs. “Organic”, The Third Dig: Add Organic Matter), Fertilizers, Rake Smooth and Pave, Agricultural Extension and Soil Tests (To Lime Or Not to Lime, and What is pH?)

Pages: 1 2

How to Prepare the Soil: An Introduction

Apr23

Along with the early daffodils comes really beautiful weather. It’s been sunny, the birds are singing…not too hot, not too cold. It’s time to prepare the soil. But first, we need to understand it.

Prepare the Soil

Herbs, vegetables, and flowers are going to be living—hopefully, thriving—in your garden for several months. For trees and shrubs, providing a good home will see them through the next decade, or the next century! It pays to give them the best conditions you can provide, and it all starts below the surface of the ground.

Axiom of the day: soil preparation is 90% of your effort.

If that sounds like work to you, you are correct! But you’re reading this presumably because past results have fallen short of expectations, and you want to improve your gardening skills. I’ve played in the “dirt” professionally for 50 years and can honestly assert: successful gardening depends on the health of the soil.

And here’s the good news. Thorough soil preparation will have benefits for many years to come. You won’t have to prepare the soil to this extent again.

The Soil Is Alive

Microbes

Seedlings in prepared soil.

Soil is more complex than meets the eye. There is a dynamic interplay among minerals, organic matter, air, and moisture. Earthworms, insects, nematodes, and tiny microbes also contribute. Healthy soil is teeming with life! These organisms play an important role in how soil functions. Without them, organic matter would not break down into those vital nutrients needed by all plants.

Vast mycelial mats of beneficial fungi, or mycorrhizae, live in close association with roots. Millions—or perhaps a billion—species of these beneficial microbes inhabit soils around the globe, many of which live within or around a particular species’ roots. Researchers estimate that there could be a trillion species of microbes living in air, soil, water, and living organisms.

Soil-borne mycorrhizae have enzymes that can unlock, or chelate, micronutrients tightly bound to soil particles, making them available to plants. These organisms can gather water and provide it to plants even though the plants’ roots don’t have direct access to moisture. And these microbes act as barriers to certain soil pathogens.

Bacillus, Streptomyces, and Pseudomonas are common bacterial microbes. Fungal mycorrhizae, such as Trichoderma, Hebeloma, and Glomus help roots absorb water and phosphorus. Other microbes, such as viruses and archaea, also inhabit the rhizosphere, the area surrounding the roots. Gardeners are familiar with the nitrogen-fixing bacteria (Rhizobium) that increase yields in legumes.

Scientists have only recently begun deciphering the enormous number of microbes and what they do for or to plants. Only a few plant families, including Brassicaeae, do not have associations with fungal mycorrhizae. Blueberries and other plants in the Ericaceae family (azalea, rhododendron) have very limited associations with mycorrhizae.

Microbes benefit from the symbiotic relationship with roots by getting carbohydrates in return. The numbers of microbes inhabiting just a tablespoonful of soil are staggering. Believe it or not, that’s greater than the number of people living on the planet! Of course, not all of these microbes are beneficial; many cause diseases in plants and animals.

Tilth

Nutrient-rich earthworm castings.

Consider yourself lucky if your soil has good tilth, or friability, to begin with. Perhaps all you’ll need to do to prepare it is to add compost, aged manure, or some fertilizer periodically.

Soil stays more biologically active over a long period of time if it is not disturbed by frequent tilling. Beneficial fungi and nematodes are especially sensitive to major disturbances. Simply scratching products into the soil surface and watering them in preserves existing microbial populations in the soil.

There are several soil types distributed throughout the United States. They’re determined primarily by the kind of bedrock beneath the surface, the kinds of vegetation growing there, climate, and management practices employed through the centuries. Minerals from rock, eroded by water and wind, will be deposited downstream or downwind.

Soil Composition

Soil is composed of:

mineral matter (rocks, sand, silt, clay)
organic matter (carbon-containing [once-living] compounds such as compost, aged manure, dead roots, dead organisms). Never use fresh manure; the ammonia content can harm plants, and it might harbor pathogens.
living organisms (such as earthworms, nematodes, microbes, insects)
air
water

Tilth and fertility are determined by relative proportions of these materials. All kinds of soils benefit from the addition of compost and other organic materials. I confess to going a little overboard on these amendments when I prepare the soil. But the plants look great!

You might be fortunate to start with soil that has good tilth. It already has physical characteristics which promote plant growth. Or experience indicates that the roots will need some encouragement to grow beyond the original root ball.

Soil that is a rocky clay, for example, dries to the consistency of brick, and will need lots of amendments to improve drainage and to encourage roots to grow vigorously. On the other hand, sandy soils need materials that will improve water and nutrient retention. Instead of repeatedly failing with plants that can’t adapt to your soil, try starting out with those that can. Working the garden over the years will condition the soil sufficiently so you’ll be able to grow more species.

Biennial foxglove (Digitalis purpurea).

Simply digging a hole in the ground, adding a cupful of compost, and plopping the plant in place won’t do the trick in heavy clay or rocky soils. Depth of topsoil, drainage patterns, ratio of clay to organic matter, air pore space (the space between particles), and, of course, fertility and pH, all enter into the equation.

The rich, black ground in our West Virginia garden needed no amendments at all; the foxgloves grew 7 feet tall! Still, I added organic matter every time new plants went into the ground.

From Awful to Awesome

First, the Awful Bit

Our first house in Maryland sat on the crest of a hill. Sunrises and sunsets were spectacular, but the soil was just awful. It was all clay and shale. Any organic matter that did exist blew away or washed down the slope. That “dirt” refused to yield even to the most enthusiastic shovel.

I created a vegetable garden farther down the slope, next to the greenhouse, that gave us fabulous crops of tomatoes and peppers. Digging in autumn leaves, vegetable scraps from the kitchen, and discarded material from my horticultural business greatly improved the soil. It didn’t take long for decomposition to begin and for the earthworms to show up.

Almost Awesome

A few years later, we moved farther south to a community that had been carved out of an old oak and hickory forest. Although the soil quality was better here than at the previous property, I continued to prepare the soil with every new project for the next 3 decades.

Before planting rhododendrons (like the one in the photo, below) in the afternoon shade, I added peat moss and pine fines to the soil. These materials were not merely thrown on top of the ground. Instead, generous quantities of amendments were incorporated (not layered) into the top 12″ to 18″ of existing soil. Then, I mixed nutrient-rich LeafGro (locally sourced compost) into the top 8″ of loosened soil.

This effort created a well-balanced mixture, composed of existing clay and loam, and the added peat moss, composted pine bark, and compost. After that, the soil remained undisturbed except for top dressings of fertilizer, compost, or mulch.

Rhododendron catawbiense.

I left the ditch behind the shrub border undisturbed, allowing rainwater to travel down the slope. Water that did not drain away would have meant death for the shallowly rooted rhododendrons.

Blueberries must have very acidic conditions, in a range from about 4.3 to 5.3 pH. Rhododendrons, azaleas, and hollies like their pH a bit higher than that, but still on the acidic side. Peat moss and pine fines incorporated into the soil helped provide the acidity and aeration.

This calibrachoa has chlorosis from high pH.

Petunia, calibrachoa, pansy, and viola also benefit from a lower (acidic) pH. Plants growing in soil with closer to neutral pH will have sickly yellowish leaves with green veins (photo, above).

A Shady Oasis

Gradually, most of the back yard grew into a private woodland. Japanese snowbell (Styrax japonica), paperbark maple (Acer griseum), Pieris, Abelia, Viburnum, Kolkwitzia, and a group of monarch birches (Betula maximowicziana) were the main players. And the rhododendrons and existing vegetation, of course.

Mulched pathways meandered under the cool canopy, and all sorts of shrubs and perennials luxuriated in that rich soil. There was a small pond, a greenhouse, and no grass to mow in the back yard. Awesome. (***Update***: As it often happens, subsequent owners of the house altered the property to suit their needs and removed almost all of those plants.)

Monitor Soil Health Over Time

Preparing the soil for vegetables is not difficult, and the results will last for years. Most varieties prosper in improved soil 10 to 14 inches deep. Lettuce and radishes need only 5 or 6 inches.

Using the space efficiently and intensively calls for carefully managing the soil. Vegetables grow quickly, fruit heavily, and, therefore, require frequent additions of nutrients.

Thoroughly preparing the existing soil will pay dividends, spelling the difference between getting a few vegetables from the garden (“Why bother?”) and having a truly abundant harvest (“Take some veggies, please!”). And, if you properly prepare the soil at the start, you’ll never have to repeat the effort to that degree.

Keep in mind, though, that, as organic matter breaks down and is absorbed by plants and other living things, you’ll need to add more compost. For top performance, plants need balanced fertilizers that are appropriate for specific uses, such as for vegetables, flowers, spring flowering bulbs, or the shrub border. That’s in addition to the compost or aged manure you originally used to prepare the soil. Lack of nutrients and compacted soils are among the top reasons for low crop yields.

Soil Testing

Contact your local Master Gardeners program, or the agricultural extension office, for information on soil testing. The results will indicate which amendments to add, and whether the pH is appropriate for the plants you want to grow. The report also includes a breakdown of the soil components: clay, silt, sand, and organic matter. Normally, I add more organic matter than soil tests recommended.

Soil pH is a measure of acidity or alkalinity. Neutral is 7.0, with acidic values below that and alkaline values above 7.0. A simple soil test will indicate pH and nutrient levels. Soil pH affects the availability of nutrients to plant roots, with most vegetables preferring pH levels between 6.0 and 7.3.

Years ago, a landscape client wanted to prepare the soil for a vegetable garden on the property she and her young family had just bought. She expressed concern for “bad things” in the ground, so I suggested that she ask for a lead test in addition to the basic tests. The cost of the basic test is very reasonable, but extra requests will raise the fee. No matter; it’s worth the cost.

The report showed a surprisingly high lead content in the soil, unusual for a newer home. So, you don’t want vegetables growing there! She submitted tests from different areas, and felt confident that the original spot was unique. Something probably had been dumped there before the house was built. Later, the family was going to have the contaminated soil professionally removed.

Lead Paint

In 1977, the Consumer Product Safety Commission banned the use of lead paint in residential properties. If you live near an industrial region, a busy highway, or where lead paint might be a concern, I strongly advise testing for lead before you prepare the soil. Local zoning authorities should have records on past property use. For more information, contact the National Lead Information Center at 800 424-5323.

Lead poses a serious health risk, especially to young children. There is no level of lead that is considered “safe enough”. And most of us grow our own vegetables for the health benefits, after all.

For now, gather your tools and your help, and pace yourselves. This is not something to be accomplished in the hour before your daughter’s softball game. So, you might as well turn it into a party—arrange for pizza delivery at the end of the day! You certainly will have deserved it.

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