If you are fortunate enough to have the opportunity to garden in the shade beneath the canopy of mature shade trees you will find many advantages not found in the full sun garden. Shade trees moderate temperatures during the hot summer months and provide the garden with structure, privacy and year-round interest. Shade is essential to the comfort of people and plants alike. A few hours of shade each day also gives the gardener an opportunity to experiment with a wide variety of interesting plants. The number of plants which can grow in the shade is enormous; in fact many plants would do well with at least some protection from full exposure to the sun.
The first thing to do when designing a shade garden is to survey the area. Observe the space over the course of a few days to see what type of shade there is. Also, take note of the types of trees that are creating the shade and what condition are they in. There are three types of shade; dappled, part shade and deep shade. Understanding the characteristics of each is important when choosing plants for your garden. While there are many advantages to gardening in at least some shade, deep shade conditions can be difficult. Only once you know the type of shade your dealing with should you begin selecting plants for your garden.
Dappled shade perhaps is the easiest type of shade in which to garden. It occurs beneath deciduous trees where there are drastic changes in the amount of sunlight reaching the ground throughout the year alternating between a patchwork of shade and sun in the summer and full sun during winter after the trees drop their leaves. Many shade tolerant perennials, such as trillium, epimedium, anemone and various bulbs have adapted to these conditions by flowering in the spring while there is still quite a bit of light entering the garden.
Part shade occurs as the sun moves across the sky. It creates situations such as full sun in the morning and shade in the afternoon. Only the most sun loving plants will fail to survive in part shade conditions. It’s perfect for those plants which tolerate sun but little shade. Afternoon shade in this situation is quite beneficial to plants, such as hydrangea, as the shade will protect them from the sun during the hottest part of the day. If the opposite is true, shade in the morning and sun in the afternoon, some plants will tend to look stressed as the coolness of morning shade gives way to full sun during the hottest part of the day.
Deep shade occurs beneath evergreens or in narrow spaces between tall buildings and can be a challenging environment in which to garden. Soil beneath evergreens is usually poor due to the lack of an annual leaf fall which in deciduous forests provides layers of organic mulch. Plants selected for deep shade gardens need to be shade demanding not just shade tolerant. When choosing your plants, remember there’s a big difference between plants which can survive in the shade and ones which thrive in it. For example, while summersweet (clethera) thrives in the shade and will grow full and lush, certain rhododendrons will end up looking scrawny in the deep shade and healthy and lush in an area which receives dappled shade.
When planting in deep shade, beneath the canopy of evergreens, amending the soil by adding compost will increase nutrients and water retention in the soil. Before you begin planting, look up to see if there are any branches which could pruned to allow dappled sunlight into the garden. Though there are many wonderful shade loving plants available, it’s often recommended to selectively prune the surrounding trees to allow at least some sun into the space.
Many plants which thrive in the shade have developed large leaves and interesting foliage as a way for the plant to capture as much sunlight as possible. Hosta is a great example of this. In the summer the foliage of shade plants often becomes the focal point of the garden. Try to choose a few plants with variegated foliage to add splashes of brightness and the illusion of light among the sea of green. Use different shades of green throughout the garden as well. Bright yellow greens illuminate a shady space and deeper blue greens create a feeling of depth, making a space feel larger than it is. Remember, colors appear different in the shade. In full sun colors can seem washed out, in the shade they are vibrant and more intense. Try to unify the garden by repeating patterns of color, textures and form.
Just as you would with flowers in the sunny perennial border, juxtapose the foliage textures and colors of your plants to create interesting combinations. A maiden hair fern with its delicate leaves will stand out more against the large leaves of a hosta than against another type of fern.
Incorporate year-round interest in the garden. Deciduous shrubs such red twig dogwood with its striking red bark and various species of viburnum with their colorful berries work well. Evergreens also add interest in the winter.
Once the soil is loosened up you can then remove any rocks, weeds, and roots. Be careful, however, not to disturb large roots close to the surrounding trees as this can hamper their growth. Once the area is cleared of the debris, add peat moss, compost and lime and till the soil once again. Grade the soil in accordance with your plan. Try to avoid any depressions in the space as water collected in shady low spots may sit without the benefit of the sun to evaporate it. When planting the shrubs, make sure to dig a hole twice the diameter of the root ball and just as deep. Back fill the hole with a mix of the existing soil and compost or manure and water immediately. I also recommend adding a good starter fertilizer made for shrubs and perennials. Place the shrub in the hole making sure that the finish grade matches the top of the root ball. The best way to make sure the perennials you've chosen thrive is to till the entire area of the proposed planting bed while adding peat moss and manure. As with the shrubs, make sure when planting to match the top of soil of the perennial with the existing grade. Once the garden is planted be sure to water the plants in the day you install them. Adding a natural stone path can create the feeling of walks through the woods or adding a bench can create a spot out of the sun on a hot summer's day.
While there are few annuals and grasses which will do well in shady conditions, there a number of shrubs, perennials, ferns and bulbs which provide virtually unlimited planting opportunities.