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Plant Trees To Transform Your Landscape, Part 2

Autumn Lake Tree Nature Leaf - pasja1000 / Pixabay

After reading Part 1 of “Plant Trees to Transform Your Landscape”, you’ve located the best spot where a tree will shade the house from brutal summer sun. Recommendations and practices presented here are based on climate and soil in the eastern part of the United States, where I live and garden, but the basic principles apply everywhere.

If your main objectives are shade, attracting wildlife, and less grass to mow, include masses of shrubs and perennials in the landscape plan as well. This article concentrates on planting trees, the dominant features in the landscape.

Native Plants vs. the Non-Natives

The choices offered in garden centers can be narrowed down to native species and non-native, or exotic, species. Within each of those groups are the original species and the cultivars (cultivated varieties). Developed by plant breeders, cultivars exhibit more ornamental or desirable—or just different—characteristics than the species.

‘Red Filigree Lace’, a delicate cultivar of Japanese maple.

Non-native plants originated in a different country or perhaps only a few hundred miles away. If the plant doesn’t occur naturally in your geographic region, it’s non-native, although some gardeners restrict use of the term to plants evolving in another country.

There are many beautiful plants, exotic to our shores, which we’ve enjoyed in our gardens. Japanese snowbell (Styrax japonica), Stewartia pseudocamellia, and the dizzying assortment of Japanese maples (Acer palmatum) are just too hard to pass up. You can compromise, if you wish, by including both natives and exotics.

To most garden center visitors, none of this matters. We buy plants that solve problems and look pretty in our yards. But, to explain the relevance of native species, I’d like to expand the subject.

The Benefits of Native Species

First, native plants require less pampering to get them established.

Species that evolved locally can tolerate fluctuations in weather patterns. Temperature extremes, rainfall, humidity, soil types, altitude, wind patterns, and local fauna shaped today’s ecosystems.

Second, gardeners concerned about local pollinators choose plants that foster bees, butterflies, and other animals that pollinate farm crops and wild vegetation.

Every third bite of food we consume is attributable to pollinators. But, you might make the case that since most crops are alien to this country, it shouldn’t matter whether we use native or non-native trees. But we need to consider what larval insects consume, and that’s foliage and other plant parts. Thousands of species—not just bees—pollinate our farms, orchards, fields, and forests.

Egg-laying female moths and butterflies, beetles, and other insects are very selective and seek the natives they evolved with to supply sustenance for the following generation.

Incidentally, honey bees are not native to this part of the world. They will, however, forage from plants grown here, many of which are related to the plants they evolved with.

Making a Case For Single Flowers

: Amaryllis with yellow pollen and white stigma.

: Double amaryllis with no anthers or stigma.

Flowers attract pollinators, which reap the harvest of nectar and pollen. But many double- and triple-petaled flowers have lost their nectaries, stigmas, and/or pollen-tipped stamens. Photos above clearly illustrate the loss of reproductive parts in a double amaryllis cultivar. If these hybridized doubles and triples have lost the ability to reproduce sexually, they can’t make seeds. They must instead be propagated asexually, or vegetatively, by cuttings, division, grafts, or tissue culture.

The anthers, supported by filaments, bear the pollen; the male portion of the flower, collectively, is called the stamen. Female parts comprise the stigma, supported by the style, and the ovary, with its ovules, deeper within the receptacle; the female portion is called the pistil.

Not all dense flower heads are pollinator wastelands, though. Species in the Asteraceae family, for example, have flowers that normally look full. This family includes all the composites, such as aster, coneflower, daisy, dandelion, rudbeckia, and sunflower. Their dense inflorescences are composed of small florets arranged in a head, called a capitulum. But the original species also have the necessary reproductive parts. The composites are one of the most successful groups of plants and are found on every continent except Antarctica.

At a local garden center last year, I watched bumble bees that were quick to land on thickly-petaled hybrid red coneflowers (Echinacea). They were equally hasty in their departure! The bees stayed on the red flowers for a fraction of a second, while they lingered on the less frilly flowers of other cultivars, mining several florets in each flower for their treasure.

Pollinators waste precious energy visiting barren double-flowered hybrids. True, not all doubles lack nectar and pollen. For the pollinators’ sake, though, select more species or varieties with simple flowers. Natural selection favors plants that set seed, of course, which is why most native plants have simpler flowers.

Photos below show examples of single-flowering cultivars. If you see a boss of stamens and pistils in the flowers, those plants can probably supply pollen and nectar to the pollinators. This is a fine point, granted, but one that is critically important to populations of pollinators, given the preponderance of double-flowering hybrids at garden centers.

: Bumble bee on perennial aster.

: Pollinator on fruit tree.

: Purple coneflower (Echinacea) with bumble bee.

Third, planting a multitude of native species helps secure the future of threatened or endangered insects and animals.

In many regions, songbird populations have declined by half due to human intervention. Some have disappeared entirely. Trees and shrubs that provide shelter, nesting sites, berries or seeds, and which host insects, can help bring back the birds. Abundant biodiversity is a valid protection against the domino collapse of interdependent species.

Civilization has claimed much of the insects’ natural environments, so each of us can play a small part in rebuilding habitats. Annual butterfly counts show drastic declines. Monarch butterflies, in particular, now have less territory available in Mexico, a major overwintering site, than in the past, when they migrated by the millions.

Maintaining brush piles for overwintering insects and animals will help repopulate your landscape early in the season. Hauling those materials off to the recycling center, however, is sure death for the insects tucked inside. Fewer insects = fewer birds and other animals.

Fourth, incorporating native plants into the landscape helps keep the entire food chain intact.

A green anole basking in morning sun.

Insects feeding on plants become food for frogs, lizards, birds, and mammals. They, in turn, become food for snakes, hawks, foxes, and other predators. In many ecosystems, insects native to the region are the foundation on which the entire food chain is based.

A rich diversity of plant material supports an enormous number of insect and animal species. Left undisturbed, populations find a balance among themselves. On the other hand, life in monoculture, such as a lawn, is sparse. Unfortunately, countless urban and suburban neighborhoods have become dead zones with all their natural vegetation bulldozed to the ground.

As we spray, mow, burn, or build in natural environments, species will continue their rapid decline. Certainly, we need places to live and work, but we can also “give back” by planting for wildlife instead of continually killing it off.

Check with your state’s native plant society, native plant finders, BeeCity USA, and the local agricultural extension service for information. In addition to these sources, find a knowledgeable salesperson at the garden center for practical advice and sources of plant material. Garden shows might feature vendors specializing in native plants as this branch of horticulture grows.

Native Species and Nativars

trees, red leaves in fall, native white oak

Red fall color in a native white oak tree.

Plant breeders have brought to the marketplace many cultivars of our native species. These nativars might have purple or red foliage instead of green, or double flowers instead of single. Perhaps they mature at a shorter height than the original species, making them a better fit for small properties.

Garden centers often stock varieties of native species, although those selling native plants might also stock the original species. By a comfortable margin, though, most of the trees and shrubs in U.S. garden centers are cultivars of non-native species. Many originated in Asia, a treasure trove of tempting horticultural novelties.

Red Leaves and Wildlife

native trees, dogwood, red leaves, flower buds

Red fall color and flower buds on native flowering dogwood.

Many trees develop red or burgundy fall foliage. Species native to the eastern U.S. with red fall foliage include sourwood (Oxydendrum arboreum), flowering dogwood (Cornus florida), black gum (Nyssa sylvatica), red maple (Acer rubrum), sugar maple (Acer saccharum), red oaks (Quercus rubra, Q. coccinea), and white oak (Quercus alba).

Beautiful fall color lures camera-toting visitors each year to the mountains, to New England, and to the Blue Ridge Parkway. The U.S. National Park Service provides an interactive map which tracks the progression of fall color.

Red- or purple-leaved cultivars sporting this color all summer are in high demand at garden centers. But if the point of planting trees and shrubs is for wildlife, we want to be sure the plants we choose will attract them. Each plant species has a particular menu of chemical compounds in their tissues that either attract or repel insects and animals. Organisms evolved a tolerance for these compounds…or they didn’t!

Purple and red leaves often repel insects due to their high levels of anthocyanins, the red pigments in the foliage. So, that defeats the purpose, doesn’t it? Not necessarily; these trees might have had green leaves that hosted insects before leaves turned red. Or insects simply tolerate the red pigments.

Oak trees support huge numbers of insects, birds, and mammals at various times during the year. This one genus, Quercus, hosts hundreds of species of moths and butterflies, although they often turn red in the fall.

Before planting a cultivar that stays red all season, though, find out if insects, such as mature caterpillars, will eat the leaves. This indicates that it could host insects for their entire life cycle. If all the larvae are tiny, however, when some larger individuals are expected, most might have crawled off to greener pastures.

If bees spend time working a flower and don’t fly off immediately after landing, that plant could be a good choice. Similarly, holes in the leaves indicate that the plant can host insects. Resources at the local university’s entomology department or botanical garden might have information that could help you choose plants that support wildlife.

The Untold Story

I’ve been packing the past couple of weeks, preparing to move to a rural location in northern North Carolina. I took a break from the work and sat on the deck, listening to the birds and insects.

One of those sounds was the hum of an approaching ruby-throated hummingbird, the only species summering in this area. Four feet away, and less than 4″ long, this tiny bird landed on a twig of the potted native dogwood tree, sitting right next to me. He then hovered near the flower buds (photo, above, with last year’s fall color), and I could see his tongue working the buds, one after another. These buds are tightly closed, yet he found something worth gathering, despite the presence of other flowers nearby.

Within a minute, another hummingbird arrived for the same reason, apparently. The two tiny birds fought for feeding rights, and the second one flew away after some impressive aerial maneuvering among the twigs. The first hummingbird continued searching for hidden sustenance held inside those buds. I’ve never seen this behavior.

My point is this: there’s much about the natural world that remains unobserved—a mystery to us—perhaps lending more credibility to the importance of using native plants in our gardens. (This section added 10/6/21.)

Deciduous Trees For the Eastern U.S.

Here’s a partial list of native and non-native trees that support wildlife. Large deciduous shrubs can substitute for trees in smaller spaces. Many other species might suit your purpose, so visit a few nurseries to see what’s available.

Most trees are sold in large plastic nursery pots, although you might also see freshly dug trees with their roots wrapped in burlap (“b&b”, or balled and burlapped).

American hop hornbeam (Ostrya)
basswood (Tilia)
birch (Betula)
black gum (Nyssa)
Carolina silverbell (Halesia)
chaste tree (Vitex)
cherry and plum (Prunus)
crabapple (Malus)
crape myrtle (Lagerstroemia)
dogwood (Cornus)
franklin tree (Franklinia)
fringe tree (Chionanthus)
hornbeam (Carpinus)
magnolia (Magnolia)
maple (Acer)
oak (Quercus)
poplar, cottonwood (Populus)
redbud (Cercis)
serviceberry (Amelanchier)
sourwood (Oxydendrum)
willow (Salix)
winterberry (Ilex verticillata)
witch hazel (Hamamelis)

Native red maple can have yellow, orange, or red fall color.

Most of the trees listed above have small- or medium-sized species or varieties. Compare suitability of native and non-native species within the genus. The familiar weeping willow, for example, is non-native and quite messy in the landscape. But smaller native willows behave better and host a large number of moths and butterflies.

Research disease resistance, flowers for pollinators, fruits for animals, sun or shade preferences, and soil types. Consider planting species that drop excessive amounts of fruit, acorns, or seedpods farther from the house and paved surfaces.

Also look into the tree’s habit of growth. A specimen with horizontal branches softens the strong vertical lines of a house. Pay close attention to utility poles and wires. Don’t plant trees near them that the utility company will butcher in future years.

Trees with invasive surface roots should be reserved for areas far from structures, pipes, and vegetable gardens. Find out from your town how close to the street or the property line you’re permitted to plant trees. Don’t forget to call 8-1-1 to locate underground utilities before digging.

Chionanthus, the fringe tree (photo, below), is a beautiful bloomer for gardens. This multi-stem plant has 2 species commonly available (C. virginicus, C. retusus), one native and the other from Asia. Male plants have larger flowers, but females set deep blue fruits for birds. The plants, however, are rarely sexed at the nursery.

Fringe tree.

The Hollies

Gardeners have used hollies in gardens for centuries. We can choose among deciduous and evergreen species.

The hollies (Ilex spp.) are another genus of primarily dioecious (Latin for “two houses”) plants that fruit on female plants. They ordinarily require a male plant, or pollenizer, to set fruit, although holly pollenizers (the males) themselves do not set fruit. Modern breeding techniques have yielded several cultivars that can make berries without pollination.

Ask your nursery salesperson for specifics regarding the need for pollenizers and how close they should be planted to female hollies. Choose the male hollies carefully; they must be closely related to the female holly and bloom at the same time. Incidentally, holly flowers are often nicely fragrant, and the bees love them! Just don’t shear them off after the buds have formed. Pruning should be minimal if you want flowers and fruits. And bees.

The Curious Case of Crape Myrtle

The Imperial moth.

Lagerstroemia indica is an extremely popular landscape tree or shrub in USDA zones 7-9. Crape myrtle, from China and Korea, was first introduced to the southeastern U.S. over 200 years ago. Adapting readily to our hot, humid summers and sometimes drought, it blooms for months despite the adversity.

What makes this non-native plant peculiar is a native moth’s preference for its leaves even when offered a multitude of its local favorites. Last year, I raised caterpillars of the huge Imperial moth. They went for the crape myrtle every time, ignoring all the others. Unless female moths instinctively target this species to host their young, the caterpillars will not likely eat these trees to the bone any time soon.

Several songbirds, including American goldfinches and juncos, feed on the seedpods.

Evergreens

You might prefer an evergreen specimen instead of a tree that drops its leaves in autumn. Look into arborvitae, chamaecyparis, hemlock, certain holly species, juniper, pine, rhododendron, spruce, and yew. Consider the shade evergreens will cast in winter, and whether sunlight might be blocked from entering windows or melting ice on the driveway.

Although not all evergreens are native to this part of the country, they make suitable nesting places and provide shelter in inclement weather. A dense border of evergreens can block fierce winter wind for a considerable distance downwind.

Soon after moving into the Maryland house in the 1980’s, I planted a chamaecyparis with deep green whorled foliage. Although it was supposed to get only 6′ tall according to the nursery, it grew to about 20′, when it was cut down by the people who bought the house from me. I left it in the front yard because birds raised a few families among its evergreen branches every year. And it looked gorgeous in the snow.

Chamaecyparis on the right, after 2010 blizzard. Sourwood on the left.

Good Looks

If you’re landscaping purely for aesthetics, plant a tree with characteristics that appeal to you. It’s your property, after all. Besides, all trees provide cover and nesting opportunities, even if they’re passed up by caterpillars.

Perhaps elsewhere you could grow perennials that offer food to wildlife. Planting a bed of milkweeds among the shrubs, for example, will help the monarch butterflies (photo, below).

While you might not consider insects important in your landscape, and, in fact, have invested considerable time and expense eradicating them, they are primary links in the food chain. A healthy landscape hosts a complex assortment of insects and animals. And with the rate at which natural habitats are losing out to development, it’s no wonder we see fewer ladybugs, butterflies, and songbirds in our neighborhoods.

Creating welcoming landscapes provides resting places for migrating birds. But they need natural corridors all along their path in order to find food and perching opportunities. We can help by planting at least part of our property with them in mind—every one of us! Provide food, water, and trees to rest in, and you might catch a glimpse of a bird you’ve never seen before.

I urge you to adopt a new attitude toward welcoming wildlife. You don’t need 10 acres to make a difference. A well-planted fraction of an acre will encourage many kinds of insects and animals to reside there. If you let them eat your plants and the sprayer hasn’t been used once this year, well done!

Monarch Butterfly Laying An Egg - Chesna / Pixabay

Monarch butterfly on milkweed.

Before Planting Trees

Let’s imagine a 2-story house and an appropriately proportional medium-sized tree. Your landscape plan calls for locating this tree off the southwest corner in the front of the house.

To prevent branches from rubbing against the siding in the future, you’ll want to plant the tree far enough from the house. Divide the mature spread of the tree by 2. Because plants tend to grow larger than the dimensions printed on the label, add a few feet to the measurement. So, a tree with a mature spread of 25-30′ should be planted 15′ or more from the corner.

While that little tree might look lonely out there, it will grow. Maybe that’s the extent of your garden project this fall. Or perhaps you’d like to develop a full garden on that side of the house with an underplanting of shrubs, perennials, and ground covers.

Walking a pathway through the garden to the side yard will feel like a walk through a park. This is a good solution where space is limited between your house and the neighbor’s. Consider your neighbor, though, and don’t plant too close to the property line. Perhaps the two of you could create an appealing garden that fills the space between both houses.

But first, it’s soil prep…please turn to page 2…

Headings:

Page 1: Are You Ready To Plant Trees?, Native Plants vs. the Non-Natives (The Benefits of Native Species, Native Species and Nativars, Red Leaves and Wildlife, The Untold Story), Deciduous Trees For the Eastern U.S. (The Hollies, The Curious Case of Crape Myrtle, Evergreens), Good Looks, and Before Planting Trees

Page 2: Soil Preparation For Trees (Slope, Outline the Bed, Heavy Clay, “How Deep?”, Adding Amendments, Organic Matter, and Time To Plant Trees (Trees In Pots, B&B Trees, Backfill, Edge, Mulch, And Water)

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Pages: 1 2

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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