The number of plants for shade on the market is truly amazing, and anyone should be able to find good selections for the shade garden.
Degrees of Shade
There is deep shade, there is light shade and there are many degrees in between. The most successful shade gardens are not those in deep shade but those in partially or lightly shaded locations. Deep shade would be under thickly planted evergreens or under deep overhangs on the north side of a building. Grass doesn't grow there and few weeds can survive.
Moderate shade is under heavy deciduous trees. There are periods in spring and fall when a lot of sunlight gets through.
Partial shade can mean that the tree coverage is light, allowing brighter conditions, perhaps dappled or shifting sunlight. It can also mean that at certain times of the day the area gets a few hours of sun. An area is considered to be in light shade when the area gets about five hours of sun, especially if part of that is around midday. The east side of the home with no overhang or trees nearby is usually a lightly shaded location.
Take a camera out to your shaded area several times during the day. If you must use a flash to take a picture at any time of the day, then you have deep or moderate shade. If at some points during the day your camera can take a picture without a flash, you have partial shade. If you can take a picture almost any time of the day without a flash, you have light shade.
Many things can modify shade conditions. Reflections from light-colored walls, fences or water can provide more light to an area. Some plants will grow in shade but struggle in dry shade or if they're competing with tree roots near the surface, a canopy of tree limbs that shed water or a roof overhang. Soil that is compacted, very acidic, alkaline or very wet may also prove inhospitable to some shade plants.
Changing the Conditions
You will have the largest variety of plants to choose from and the most successful growing conditions if you have partial shade or light shade. Some conditions can't be changed, but the gardener can often trim and thin trees to provide more light to an area.
If you are willing to try more drastic measures, you could try removing the structure producing the shade, such as a fence, shed or overhang, or add a reflective surface.
If dryness is a problem, you can irrigate the area or hand water. Mulch can be used to hold soil moisture. Don't cut out and remove tree roots unless you don't like the tree, and never change the grade under a tree by more than three inches. That means you should not make a retaining wall and bring in a foot of topsoil under a tree. This can kill the tree.
Choosing Plants for Shade
Choose shade plants that also prefer moist or dry conditions, acidic or alkaline soil or other conditions of your site. Select perennial plants that are hardy for your area. Plants at the northern end of their range may require more sun than when grown in the South. Some plant species have varieties that will grow in partial shade but other varieties prefer full sun. Be honest in evaluating your shade conditions and pay attention to the plant labels and catalog descriptions.
You also need to think about what you want your shade garden to look like. Some want a uniform look with little maintenance. Others want a variety of textures and color and season-long interest, much like the perennial bed in the sun.
Gardeners with shade should be aware that while there are many plants that bloom in shade, most shade plants are chosen for their foliage color or texture rather than their flowers. If you want a lot flowers, there are some annual plants that will do well in shade that can be used among the perennials. Spring- and fall-flowering bulbs can be used in places where trees drop their leaves and the area gets more sunlight at some times of the year.
Plants with silver, white or gold foliage light up shady areas and add visual depth. But don't overdo the use of these plants. They lose some of their power if there is no contrast. Plants with deeply colored red and purple foliage may fade into the background in the shade. Just as when planning a bed in the sun, a variety of sizes, shapes, colors and textures provides visual interest.
Shade Plants for Particular Uses
Trees and shrubs for partial and light shade include azaleas, beautybush, many boxwoods, camellias, many dogwoods, filberts, firs (Abies species), hazelnuts, hornbeam, horse chestnut, many hydrangeas, Japanese maples, kalmia (mountain laurel), ligonberry, some magnolias, paw paw, redbuds, rhododendrons, some yews and some viburnums.
Perennial plants for partial shade include arisaema, aruncus, astilbe, bleeding heart, bergenia, brunnera, campanula, cimicifuga, columbine, corydalis, digitalis, epimedium, ferns, helleborus, heuchera, heucherella, hosta, lily of the valley, liriope, tiarella, tricyrtis, trillium, violets and violas.
Good shade ground covers include ajuga, mazus reptans, pachysandra, sweet woodruff, wintergreen and vinca.
Some vines for shade include some akebias, confederate jasmine (trachelospermum), Dutchman's pipe (aristolochia), parthenocissus and porcelain vine (ampelopsis).
Annual plants and bulbs for shady areas include abutilon, begonias, caladium, calla, crocus, coleus, fuchsia, impatiens, muscari, narcissus and snowdrops. Houseplants and other tropical plants can be used in the shade during frost-free months to lend an exotic touch.