THIRD IN AN EIGHT-PART SERIES
byGLENN WITHEYandCHARLES PRICE
Knowing your soil is as essential as good planting technique
AFTER YOU HAVE DRAWN UP A BORDER PLAN that is both realistic and meets your aesthetic goals (see “Border Basics 2; Creating a Design,” May/June 2002), the next step is to implement the design. We are assuming, at this point, that you have noted essential matters such as winter drainage, animal travel routes, and how the sun tracks and where the sunny and shady areas are from spring through fall. We also assume that the basic hardscape—paths, fences, walls, edging, main irrigation lines—is in place.
The first step is to get rid of the weeds. What sorts of weeds are present on the site? Are they annual or perennial? How will you eradicate them? Organically or with chemicals? Whatever method you choose, it needs to be effective. Some perennial weeds can take up to a year to be fully eradicated, even with strong herbicides. If we know a site has been infested with tenacious perennial weeds, we will (after an initial eradication attempt) amend the soil and water the entire area to encourage any remaining pieces to grow and reveal themselves. Another attempt at removal ensues before planting. That said, there may be cases where you simply can’t win—for example, if you have an established colony of plants like the deciduous horsetail, Equisetum arvense, your best option is to garden elsewhere on the property, or else to incorporate it into a damp meadow scheme as a textural element along with other strong growers such as large hostas, ferns, and Astilboides tabularis.
GETTING RID OF GRASS
A lawn can be one of the easiest sites to prepare, since, if you’re willing to use an herbicide like glyphosate (Roundup), there is no need to strip the sod. A dead lawn provides organic matter for the planting bed, so why go to the expense and trouble of hauling it away?
You may have a problem if the lawn was installed as rolled sod, which can have plastic mesh under the surface. The mesh is usually fine enough that a tiller can tear it up without clogging the blades. It is also fine enough that it shouldn’t present a problem for tree roots or the crowns of herbaceous plants. However, we don’t recommend planting through it if you haven’t tilled the area first.
Another problem can be the makeup of the grass itself. A fine fescue is easier to get rid of than Bermuda grass or some other invasive species. Do your homework and check out what the makeup of your lawn is before you proceed. Also, there may be repercussions if the lawn has had a recent (or long-lasting) application of broadleaf herbicide.
EVALUATING SOIL TILTH AND FERTILITY
One of the cardinal rules of border making is to pay close attention to the structure of the soil. This is especially true if you’re dealing with a site ravaged by recent construction work—paint residues, drywall, concrete, nails, and other debris often lurk in soil around such sites. Be sure to remove as much of the debris as you can. (Metal detectors can be helpful in finding nails and screws.) If the contamination is extensive, you may have no other choice than to haul the soil away and replace it—an expensive but unavoidable step.
Assuming you’ve dealt with these issues and your soil is halfway decent, think twice about amending it heavily. There has been a concerted movement, which started in Europe, to create plantings that thrive with lower soil fertility, Plants with low nutrient needs seldom need staking or intensive upkeep. By matching your planting to areas of higher and lower fertility, you can lessen the amount of maintenance you have to do, and the “natural” variation of the flora will provide an additional level of interest to the garden as a whole.
Many books extol the virtues of double digging—digging to the depth of two spade blades to break up the soil and incorporate organic matter into the lower area. This kind of intensive preparation is largely a relic of the past. Yes, a construction site, disused roadway, or a well-trodden path will need to be broken up in order to get the plants established. But as long as your soil isn’t too compacted, thoughtfully chosen plants will most likely grow just fine without your having to double dig.
In all but the worst situations, a few years of mulching, feeding, planting, and dividing will work wonders on the tilth of the soil. The continuous ministrations of microbes, plant roots, and earthworms will do the rest. Soil texture is one of the few areas in which those of you who garden where the soil freezes deeply have the advantage over gardeners in milder climates. As long as you mulch in winter to keep your plants in the ground as it heaves to and fro, you’ll have a certain level of tilth restored nearly every year.
Clay soils present their own unique problems. Working a heavy clay soil when it’s wet can result in huge, heavy clods that dry and harden, requiring yet more work to break them up. If you till wet clay, you may wind up with an airless slurry that sets like mortar. Conversely, if the clay is too dry, you will feel as if you’re working on concrete. It needs to be, as Goldilocks preferred her porridge, just right. Then you will have a much easier time adding compost, gypsum, or other amendments to improve the tilth. Sandy soil is more amenable to being worked at a variety of moisture levels.
Planting Tips and Caveats
If you have a limited budget, consider temporary alternatives to expensive hardscape materials such as stone flagging. This is only realistic, however, where future disruption to the plantings can be kept to a minimum. Using gravel, wood chips, or various recycled materials can be a good way to cushion the financial impact.
Annuals can be useful in helping to fill in the blank spaces of a freshly planted border, as long as you don’t let them overwhelm the permanent plantings. In the planning stage, we often include spaces specifically for annuals. These areas can be fun to play with, allowing you to change the plants each year, or even seasonally.
If you have an irrigation system already in place, don’t forget where the lines are! Also, be careful not to let tall perennials block spray heads. There are a number of newer irrigation systems that are worth investigating. Choose one that is easy to repair, and learn to do it!
If the potting medium of a containerized plant is radically different from what is in its new bed, tear away some of that soil and work in a bit of the “real stuff.” A sharp difference between the two soils-caused mainly by the different drying and decomposition rates of organic materials such as bark, peat, and compost-can prevent the plant from taking up as much water as it needs.
If there are any self-sowers that you want to spread within the border, timing is critical when spreading mulch. If spread early in the growing season, it may suffocate desirable volunteers. Often it is best to leave certain areas uncovered until later in the season, allowing the annuals or biennials a chance to get established (having first made sure, of course, that you’ve eliminated any nasty weeds).
If you need to “upgrade” your existing soil, good-quality organic fertilizers are your best bet, especially unsterilized compost, which will add microbial life to the soil. Some synthetic fertilizers, on the other hand, may contain chemicals that are better suited to a toxic waste dump than the garden. If you’re unsure about what nutrients your garden has or lacks, contact an extension service agent about soil testing.
The use of animal manures requires a certain amount of caution, since poor-quality manure isn’t worth the cost, and may even have an adverse effect on plants. Good-quality manure has been thoroughly composted so it won’t burn, and is sometimes screened to make it easier to spread. It’s a good idea to obtain a small sample and evaluate it before ordering a truckload. Also bear in mind that manures can harbor certain pathogens, such as E. coli, which may cause a problem for the elderly or very young.
Even with high-quality manure, you need to be careful. In our benign Seattle climate, we spread a two- to four-inch layer during the early winter months while plants are still dormant. Manure applied too late, while new growth is tender and lush, results in leaf burn. We have also found that certain bulbs, such as Dutch hyacinths, don’t enjoy emerging through the manure, since it becomes trapped in the unfolding buds. Manure can also be conducive to the growth of botrytis, a danger to many bulbs, and can enhance the spread of phytophthera, a soilborne pathogen that is naturally present in our soils.
Spacing young plants can be tricky—remember to leave room for them to grow! The desire to squeeze in “just one more” can lead to dire consequences. Make sure you know the eventual size of what you’re planting, and bear in mind that climate and soil fertility can both affect eventual size.
Severely pot-bound plants will need to have their root systems teased out, cut, or scored in order to keep the roots from girdling the plant and to encourage them to grow out into the surrounding soil. (There are exceptions: neither Siberian iris nor peony roots should be disturbed in the spring, although both of these plants can take harsh treatment in early fall.) The general recommendation is to not purchase pot-bound plants in the first place. There are many reasons, however, why you may end up with plants in this condition, so it is best to learn to deal with them. Trees are the exception, as they may become dangerous in the future if they have poor root structure when you buy them.
In the garden, plants should be planted at the same level as they were in the container. Most plants don’t enjoy being buried too deep, as less oxygen gets to the roots, and some may develop stem rot. Planting too high allows water to run off too rapidly and exposed roots to be damaged.
Firm the soil around the plant’s crown and water it in well, making sure that there are no air pockets in the surrounding soil. Soil that is too loose and fluffy will prevent efficient water uptake. Also, wind can push over plants too lightly anchored. In planting larger-size trees or shrubs, we will often give the plant a “garden hose enema,” forcing the hose stream in deep to ensure that no large air spaces are left. This can be repeated several times, allowing the water to drain away in between so you can check for soil settling and add more as needed.
Planting late into the fall can work in mild climates because the soil is often still warm, and the plants will have time to send out new roots. But where severe frosts occur, plants can be heaved out of the ground, so spring planting is generally best.
Mulching can be helpful, both before planting a bed, if the area is lying fallow for an extended period of time, and after the initial planting has been completed. With a mulch, soil moisture stays more even, less irrigation is needed, and annual weeds are less likely to germinate. A layer of mulch can also help unify a garden visually.
How thick or thin a layer of mulch to apply and what material may be best will vary from region to region. Depending on the heat, humidity, and rainfall, certain mulches will decompose quickly; others may form an impenetrable layer. It is important to explore the local options and determine which mulches will work best for you.
When you’re finished with the initial planting, sit back and enjoy what you have accomplished. This interlude may last only a short time unless you’ve done your homework. Time will tell. Even if the results don’t turn out as you’d hoped, remember that even the best gardeners make mistakes. Wince, laugh, and keep gardening. H
Tools of the Trade
Quality is the key with tools-they should be strong yet relatively lightweight. If you don’t already have your “arsenal,” expect to pay at least several hundred dollars for a basic complement of shovel, spade, fork, trowel, and pruners. We also like to include a sturdy soil knife.
We have often observed people installing gardens with a scoop-shaped shovel. These shovels are meant to move material, not to dig about in a border. Shovels that are only slightly concave are more desirable for everyday garden use. In tight spaces or established beds, small spades, such as a poacher’s spade, are ideal. Garden forks also work well in lifting and breaking apart established clumps of perennials. Make sure your fork is made of stainless steel or other stiff steel, as bent tines are horrible to work with. –G.W. & C.P.