Growing plants in filtered and partial shade

Plants that grow in filtered and partial shade receive about the same amount of light. Here's what you should consider when choosing these special plants.

Filtered shade can be found beneath any open canopy that provides dappled sunlight throughout the day. The source of filtered shade might be the overhead boughs of a loose limbed or small-leaved tree, such as dogwood, silverbell, or stewartia, or perhaps very tall, widely spaced evergreen pines.

Filtered shade is also found beneath a pergola, an arbour, or beside a picket fence or lattice panel. Plants grown in filtered shade often show a full, mounded shape and rarely stretch toward the sun, because they receive a steady, yet intermittent, light supply all day long.

The same plants that grow in filtered shade also often thrive in partial shade, a situation in which buildings, walls or thick tree canopies; or closely spaced trees and shrubs block light for all but three to four hours daily.

The best kind of partial-shade situation for gardening is usually found on the east side of a house or along a woodland edge, where plants receive sunlight in the cooler hours of the morning and are shaded and protected from the hot afternoon sun. Morning sun dries dew from plant leaves promptly, which reduces fungal diseases, and it gives plants a short but intense period of exposure to sunlight, followed by a long recovery period in the afternoon. This is a situation that can help you grow a wider selection of plants than you normally could if you live where summers are hot, because many plants that grow in full sun in cooler climates can wilt and eventually die if exposed to full sun in hot areas.

• Astilbe
• Azalea
• Bergenia
• Bleeding heart
• Boston ivy
• Bugleweed
• Caladium
• Calla lily
•  Camellia
•  Clethra
•  Cohosh
•  Columbine
•  Cyclamen
•  Daylily
•  Dogwood
• English ivy
• Epimedium
• Euonymus
• Ferns foamflower
• Fuchsia
• Garden phlox
• Goatsbeard
• Hosta
• Hdrangea
• Impatiens
• Japanese anemone
• Japanese maple
• Lungwort
• Mahonia
• Mountain laurel
• Pachysandra
• Phormium
• Redbud
• Red buckeye
• Rhododendron
• Spiderwort
• Stewartia
• Trillium
• Yellowwood

Underneath it all, thirsty tree roots are always competing with garden plants for water and nutrients. Trees with many surface roots, such as birches, beeches, maples, and apples, are the worst offenders.

1. If you're planting beneath a shallow-rooted tree, consider planting dry-soil-adapted groundcovers like vinca or epimedium. Or build a shallow berm or raised bed.
2. Keep the bed at least 1.8 metres (six feet) from the trunk of the tree to prevent damage to the trunk and shallow roots.
3. Line the floor of the bed with thick, perforated plastic to keep tree roots from invading your bed.
4. To avoid root competition altogether, create shade gardens under tree species with deeper roots, such as oak, hickory, or other nut trees.