Tidewater Gardening - June 2006
Making It in the Shade
K. Marc Teffeau
As some of the older home landscapes mature, shading from large trees can result in changes in what plants will grow in an area and what plants will not. Landscapes change their degree of shade over time. As trees and shrubs mature, the landscape receives greater shade. What was once a sunny garden may evolve into a shady one.
Many gardeners view shade as a challenging situation for growing plants. While some plants do not grow well in low light, numerous others thrive under these conditions. Just as moisture, temperature, and soil conditions may limit plant growth, the amount of shade present may determine which plants will grow successfully. In addition to low light levels, plants growing in the shade must compete with shading trees for nutrients and water, and tolerate poor air circulation.
An abundance of large trees and shady areas in your yard can be a challenge to the creative gardener, rather than an obstacle to good gardening. Shady places that provide cool, refreshing areas of beauty during summer’s heat also can contribute color and interest to the landscape throughout the growing season.
There are many plants that are adapted to shady sites. If you are struggling, trying to grow a lawn under a grove of trees, consider a different approach by adding variety and class to your lot with plants that thrive in the shade.
Gardening in the shade doesn’t have to be frustrating. Some plants will tolerate relatively low light, and a few actually thrive in it. You can choose from an array of flowering annuals, perennials, bulbs, and woodland plants for color. Many groundcovers do well in problem areas. In light shade you might even be able to grow a few herbs or leafy vegetables.
Analyze the degree of shade in your garden periodically to determine if changes in plant materials may be needed due to increased shade from a maturing landscape. The trick is to know which plants are most likely to succeed and then to give them the kind of care that will improve their chances. You also have to be willing to experiment a bit to find which plants grow best in your particular locale.
First, assess how much light the plants will actually receive. Light shade may be described as an area that is shaded but bright. It may be completely shaded for only several hours each day. The sun’s rays may be blocked by a wall or building for several hours at midday, but the area is sunny the rest of the day.
Light shade may also be found in areas that receive filtered or dappled sunlight for longer periods. Edges of shady gardens or areas under the canopy of solitary, lightly branched trees are typical of filtered sunlight. During the heat of summer, light shade at midday will provide a beneficial cooling effect. Flower and foliage color may be more brilliant when plants are shielded from intense midday sunlight.
Partial or medium shade is present when direct sun rays are blocked from an area for most of the day. Many established landscapes have large areas of partial shade, where sections of the yard are shaded by mature trees for much of the day but receive some direct sun early or late in the day. Bright, north-facing exposures may also be classified as medium shade.
Full shade lasts all day. Little or no direct sunlight reaches the ground at any time of the day. There may be reflected light from sunnier areas of the yard or off light-colored walls.
Dense shade refers to full shade under thick tree canopies or in dense groves of trees. Areas under stairways, decks or covered patios on the north side of the house receive full shade. Keep in mind that light patterns change with the seasons. An area that is in full sun in summer when the sun is high in the sky may have medium shade in spring and fall, when the sun is at a lower angle. Study your garden through the seasons to accurately determine what type of shade is present.
Densely shaded areas beneath large trees or under the overhang of a building present more problems than do situations of partial or light shade. Although partially or lightly shaded areas receive direct sunlight for only a small portion of the day, light intensity is still quite bright. There are numerous plant choices you can make in these locations, though by no means as many as are possible with five or more hours of direct, full sunlight.
Light is not the only major concern when gardening in shady areas. Frequently, inadequate moisture can be a problem. The thick canopy of a large tree or the overhang of a house will act as an umbrella, deflecting rainfall away from the ground directly beneath it. Worse yet, trees and shrubs will compete with smaller plants for every drop of moisture that reaches the ground. It is vital that plants growing in the shade of large trees and shrubs, or sheltered by your home or garage, be watered regularly even during times of seemingly adequate rainfall.
Soil fertility also can be a source of trouble. Trees and shrubs fill the soil with feeder roots that greedily use up nutrients as readily as they are applied. It often seems that the more you water and fertilize, the more roots with which you have to contend. Yet adequate fertility is an absolute must for all your plants because without it they are bound to be small and their growth will be weak.
In most cases a spring application of a balanced fertilizer, followed by one or two applications as the season progresses, will help your shade plants survive the competition of tree and shrub roots. If root competition is a serious problem, planting in containers above ground is a viable alternative. Containers should be replanted each spring with annuals, since bulbs or perennials cannot be expected to survive winter’s cold.
With few exceptions shade-tolerant plants will do best in well-drained, relatively fertile soil. Which plants will be the showiest in a shady situation? If you’re looking for a continuous display of color from late spring till frost, annuals will work well except in dense shade. Flowering annuals do not bloom well in heavy shade; they all blossom more profusely as light is increased. Some annuals, however, do better in light shade than in full sun, which may fade colors or cause wilting the moment there is any moisture stress.
Impatiens is popular annual for shady locations and are available in a wide range of intense colors and heights. Browallias, coleus, wax begonias, dwarf salvias, and other shade tolerant annuals will begin blooming soon after frost danger is past if you start with robust young bedding plants. It doesn’t make sense to direct seed annuals for a shady garden in our climate. By the time they accumulate enough food reserves to bloom attractively, the growing season is almost over.
Spring flowering bulbs can be planted in deep shade provided you treat them as annuals, planting new bulbs each fall and then digging them up and discarding them once they’ve bloomed. The bulbs you buy already have miniature flowers inside. All that’s needed is a cold winter in the ground for those flower buds to emerge in spring. In order to repeat the performance the following year, though, the leaves must receive full sunlight for most of the day until they die back naturally. This builds up food reserves for the next blooming cycle. Without enough sunlight, you’ll get leaves each year but no flowers.
Some spring bulbs such as crocus, scillas, snowdrops, and species tulips bloom and produce leaves early enough, before the trees leaf out, so that they receive adequate amounts of sun to blossom annually in a lightly shaded area. Daffodils naturalize beautifully in an open wooded area.
The tuberous begonia is another bulbous plant that grows well in light shade, since its delicate blossoms cannot stand full sunlight. Tuberous begonias are very tender, though, and must be stored indoors over the winter and not set out until frost danger has passed.
Many perennials bloom reliably in light shade, but some will blossom in fairly dense shade. Most of these are woodland plants that usually blossom very early in the season, though there are some exceptions. The fringed bleeding heart blooms all season, and black snakeroot blossoms mid to late summer.
Most woodland flowers are muted and delicate rather than bold and brightly colored. Unlike the annuals, which tend to bloom throughout the growing season, most perennials only flower for a few weeks. When not in bloom, though, their foliage still plays an important part in the shade garden, adding variety in form and texture as well as in shades of green. Flowers often are followed by interesting seed pods or bright berries.
Some perennials, such as hosta lilies, usually are planted for their attractive leaves rather than for their flowers, which in most species are not particularly colorful or showy. Ferns don’t bloom at all, but there’s hardly a shady garden that wouldn’t be enhanced by their grace and beauty.
In dense shade and problem areas where it’s hard to tend plants, there are several perennial groundcovers that can be used effectively. Japanese spurge and periwinkle are two good choices in this area. Other groundcovers such as wild violets, lilies of the valley, goutweed, and wild ginger are more durable.
Another good choice is Liriope, a grass-like perennial that grows in dense, low clumps in full shade or partial sun and bear lilac colored flowers which are followed by black fruit. There are several varieties, including giant and variegated liriope. Many of these tough groundcovers can survive in a root-filled location that would be impossible for annuals or other perennials.
So don’t let shady area be a discouragement to your landscaping desires. Become creative and adapt!