Table of contents for Shaded Gardens
In most densely shaded sites, either large trees or buildings block the sun. And any barrier than can block sun can also stand in the way of rainfall, which explains why dense shade and dry soil go hand in hand. Your task is to find drought-tolerant plants that require scant light and moisture. It's a design bonus if they also brighten dim garden spots with colorful blossoms or leaves. If you also use a couple of light-reflecting tricks to supplement sunlight, all that's left for you to do is to irrigate as needed.
Bringing Light into Darkness
The best plants for making a dark spot appear brighter are those with pale, light-reflecting colors. White flowers and variegated or lime-green foliage will not only enliven dense shade, they will also make the site seem spacious. Choose plants like variegated Solomon's seal, hostas with white-edged leaves, and silvery-leaved dead nettle for the light-reflecting quality of their leaves. Shiny evergreen leaves like those of epimedium also brighten dark shadows by reflecting light that filters through the trees. Colored flowers for lightening dense shade include those of pastel-flowering hellebores and spring bulbs.
If your shady garden bed is next to a wall or fence, painting the backdrop white or a light color will reflect light onto the plants. Another light-reflecting feat is achieved by disguising mirrors behind openwork gates or window frames, and then hanging them on a wall or nearby fence. The reflection of light from the mirrors brightens the garden bed and makes the space seem larger. A bird bath, basin, or small pond will also reflect the sky like a mirror, brightening the shade.
Planting Between Tree Roots
Under the soil's surface, around the trunk of a tree, the roots are thick and woody, almost like underground branches. The good news is that you can plant shade-loving, drought-tolerant bulbs, groundcovers, and perennials in small pockets of enriched soil between these mature roots with little risk of damage to the tree.
Here's how it's done. Using a sturdy trowel, dig out a pocket of soil at least twice as big as the root ball of the new plant. If possible, be even more generous. Add a few handfuls of compost and mix it thoroughly with the existing soil. Remove the plant from its container and loosen the soil around the root ball. Place the loosened soil ball of the plant in the hole, set the growing point, or crown, level with the surrounding. Fill the hole around the plant with soil, firm the soil around the plant's roots, and water well. Cover the planted area with a 2 in (5 cm) thick layer of compost as a mulch to conserve moisture.
It's a jungle down below. The roots of many trees are most numerous close to the surface where they compete with the roots of smaller garden plants for the limited water that manages to trickle through the canopy to the ground below. And, although many plants can tolerate temporary drought after they have developed mature roots, young and tender plants almost always need supplemental water to get them off to a strong start while they are growing an adequate root system.
The most efficient way to provide supplemental moisture to a dry-shade garden is to outfit it with a soaker hose. Simply arrange the hose on the ground so that it snakes around your plants, and then cover it with loose mulch to hide it from view. Turn the hose on for several hours or overnight about once a week during dry weather, or more often if temperatures are very hot. The moisture will seep deeply into the soil with no runoff, fostering the development of deep, water-seeking roots. With the development of deep roots, your young plants won't wilt during brief dry periods.
One inch (2.5 cm) of water per week is the standard recommendation for supplemental watering. Measure the water by setting a shallow tin can or other container on the ground where the irrigation water will drip into it. When the container collects water to the recommended depth, you can stop watering. Note the time it takes to provide the right amount of water, and in the future, water for the same time period with each watering, and you won't have to measure again.
When dry shade is due to the close company of trees, dry soil typically prevails from spring to fall, when tree roots take up the most soil moisture and the branches overhead shed rain like a giant umbrella. Not surprisingly, many plants that are native to woodland areas, including asarum, columbine, wood aster, and dainty blue-flowered phlox, are perfectly attuned to the seasonal changes in sunlight and soil moisture typical of their ancestral forest habitat. These and other adapted plants are top choices for a care-free garden in dry shade.
Nature can be unpredictable, and even these plants can be set back when drought comes at unexpected times, particularly early spring. During unusually dry springs, be prepared to provide water to make up for rain that fails to fall. For these plants, which are often willing to accept dry soil in summer, moisture in late winter and spring is essential for a happy and healthy life.
Elements of Design
Keep in mind that every square inch does not have to be occupied by plants. In fact, the visual contrast between foliage and soil-covering surfaces of stone, wood, or pebble mulch, as well as seating areas and garden art always creates visual interest and excitement in the garden. Dry, shady garden spots are no exception. Because such areas are usually sheltered from the elements, they are excellent spots for placing a bench, an artful stone, a bird feeder, or statuary. Indeed, adding something as simple as a pair of stools made of log rounds can instantly turn a dark, dry place into an inviting outdoor room.
If your problem spot is a narrow side yard, you can make it feel more accessible and spacious by emphasizing low-growing plants, such as asarum, epimedium, or hostas, planted along the edges of a walkway. Another strategy that makes narrow corridors more appealing is to add several containers planted with shade-tolerant annuals like coleus and impatiens, or hardy flowering perennials like astilbe and hydrangea.