Published on Organic Gardening (http://www.organicgardening.com)
Gardening in the shade challenges the talents of many gardeners because they fight the shady conditions rather than adapting to them. You can't grow a lovely lawn or an English flower border under trees. But you can grow a diverse, beautiful garden. Instead of struggling to grow sun-loving flowers and lawn grass on a shady site, why not design a garden that will actually thrive in shade? By carefully choosing flowering shrubs, perennials, annuals, groundcovers, and ferns adapted to shady conditions, your garden will be not only colorful and interesting but also easy to care for!
The Challenges of Shade Gardening
Study your shady site to decide if you have dense, light, or partial shade. In partial shade, where some direct sun shines for a few hours a day, you'll be able to grow a wider selection of plants. Light or dappled shade also allows a wider selection than dense all-day shade cast from a thick-foliaged tree. If tree shade is very dense, you might want to thin out a few tree branches (cutting them off at the trunk) so that more light reaches the ground, creating a light or filtered shade. You may have to thin out branches every few years to maintain the effect.
In a shady area, it's often the case that poor, dry soil limits plant growth more than lack of light. Shade spots under trees can often be remarkably dry, because the trees' surface roots suck up all the available moisture and nutrients. The lack of moisture, not the shade, often limits your endeavors. You'll know if dry, root-clogged soil poses a problem because the ground will feel hard and compacted, and you'll have trouble digging a hole with a trowel.
If the soil in your shady spot is compacted, you can layer chopped-up leaves and twigs over the area. In a year or so, they will decompose into a rich humus. Chop the dry leaves to the size of 50-cent pieces with a bagging lawn mower, and spread them several inches deep beneath the tree boughs. Sprinkle the leaves with a compost activator and keep them moist. Repeat this procedure annually until the leaves have rotted into a deep humus. By then, earthworms will have moved in and begun to loosen up the subsoil. Only when you have a loose, friable soil can you begin installing a diverse shade garden, though tough groundcovers such as epimediums (Epimedium spp.) will grow in dense tree shade and poor soil.
Sometimes tree roots interfere with digging a planting hole for a shade-loving shrub. When this happens, dig an extra-large planting hole and sever all interfering tree roots smaller than 1 inch in diameter. Mulch the soil with compost to nourish the young shrub. The large planting hole should give the shrub enough growing room to get established before tree roots return.
Creating a Shade Garden
For the most pleasing effect, arrange plants beginning with the tallest at the back of the garden, or in the center if it is to be viewed from all sides, and filling in with the shortest. You might start by planting a shade-loving understory tree, then arranging groups of broadleaved evergreen shrubs. After these woody plants are in place, add large groups of flowering perennials and underplant them with groundcovers to keep the soil cool and moist. Spring-flowering bulbs often flourish beneath trees, soaking up all the sun they need in spring before the tree leaves emerge. Plant them in large drifts together with the perennials.
Choose white and pastel-colored flowers as well as white-, cream-, or yellow-variegated and gold-and chartreuse-leaved foliage plants, such as hostas and golden hakone grass, for your shady site. These light colors pop out of the shadows rather than receding into the gloom like red or purple flowers tend to do. For more on designing a garden, see the Garden Design entry; for more on landscaping your shady areas, see the Landscaping entry.
With a careful selection and placement of plants, you can transform your dim spot into a cool, flowery retreat. It just might become the best-looking part of your yard.
Plants for Shady Gardens
The wide selection of plants listed here will brighten up any shady corner. Most prefer partial or filtered shade, but some can do well even in full shade. Check plant hardiness of perennials, groundcovers, and shrubs, and choose plants that are hardy in your area. If you have room, consider flowering understory trees like dogwoods and redbuds that do well in woodland conditions.
Annuals
Begonia Semperflorens-Cultorum hybrids (wax begonias)
Browallia speciosa (browallia)
Solenostemon scutellarioides (coleus)
Impatiens wallerana (impatiens)
Myosotis sylvatica (garden forget-me-not)
Torenia fournieri (wishbone flower)
Viola × wittrockiana (pansy)
Perennials
Astilbe spp. and cultivars (astilbes)
Dicentra eximia (fringed bleeding heart)
Dicentra spectabilis (common bleeding heart)
Digitalis grandiflora (yellow foxglove)
Digitalis purpurea (common foxglove; reseeding biennial)
Filipendula ulmaria (queen-of-the-meadow)
Helleborus spp. (hellebores)
Hemerocallis spp. and cultivars (daylilies)
Heuchera spp. and cultivars (heucheras, alumroots)
Hosta spp. and cultivars (hostas)
Mertensia virginica (Virginia bluebells)
Osmunda cinnamomea (cinnamon fern)
Phlox divaricata (wild blue phlox)
Phlox stolonifera (creeping phlox)
Polygonatum spp. (Solomon's seals)
Primula spp. (primroses)
Pulmonaria spp. (lungworts)
Tiarella cordifolia (Allegheny foamflower)
Groundcovers
Ajuga reptans (ajuga)
Asarum spp. (wild gingers)
Bergenia cordifolia (heartleaf bergenia)
Carex spp. (sedges)
Convallaria majalis (lily-of-the-valley)
Fragaria vesca (Alpine strawberry)
Galium odoratum (sweet woodruff)
Epimedium spp. (epimediums)
Hakonechloa macra (hakone grass)
Lamium maculatum (spotted lamium)
Liriope spp. (lilyturfs)
Mitchella repens (partridgeberry)
Pachysandra terminalis (Japanese pachysandra)
Shrubs
Calycanthus floridus (Carolina allspice)
Daphne cneorum (rose daphne)
Ilex crenata (Japanese holly)
Kalmia latifolia (mountain laurel)
Kerria japonica ‘Variegata' (variegated Japanese kerria)
Leucothoe spp. (leucothoes)
Mahonia spp. (mahonias and Oregon grapes)
Nandina domestica (heavenly bamboo)
Prunus laurocerasus (cherry-laurel)
Rhododendron spp. and cultivars (rhododendrons and azaleas)
Ribes alpinum (alpine currant)
Sarcococca hookerana (Himalayan sarcococca)
Skimmia japonica (Japanese skimmia)