In dry shade, plants wilt and are stunted and simply do not convey that green, lush vigor that imparts a primal sense of well-being — in flora and us. Dry shade is most obvious when weather patterns turn droughty, but if you tend to brood about your garden, it’s a condition that never leaves you.
Anytime is a good time to plan a fix; now is also a good time to effect one. Garden beds can be worked and planted until the ground freezes. Shrubs and ground covers would much rather endure the trauma of planting in November than in the gathering heat of May. Our desires are secondary.
Walls, eaves and fences conspire to create dry shade, but for most of the garden, the condition is found beneath trees, both deciduous and evergreen.
One approach is to install irrigation. This is not as simple as it seems. Overhead sprinklers waste water, contribute to foliar diseases and aren’t very efficient; shrubs and trees tend to block the jets of water. In his new book, “Planting the Dry Shade Garden,” Graham Rice suggests the use of soaker hoses or drip irrigation, an efficient way to water roots without troubling the rest of the plant. My advice: Pay close attention to irrigated soil, because excessive watering can harm trees even if the hostas and ferns just lap it up.
The standard advice is to try to get more light into the dark garden by removing lower limbs of trees and thinning out branches that are crossing, dying or just growing the wrong way. This fine pruning takes some finesse: Use someone you trust. You can also remove a good percentage of trees from a backyard woodland without losing the effect. Scrawny and self-invited specimens are obvious candidates for the chipper. The third leg of this tripod is to pick the right plants for the woodland floor.
Rice, a British plantsman who also gardens in Pennsylvania, devotes much of his book to recommending suitable plants. I am nodding in agreement with most of his choices, because I have been dealing with the phenomenon for 17 years. The following ground covers work: epimediums, lamiums, sweetbox, various hellebores, pachysandra and the euphorbia known as Mrs. Robb’s spurge. Plant them small and water them once or twice a month until the root systems get established, in about 18 months. In hot, dry spells, water them weekly.
In one of the sunnier openings in this edge of the garden, I have gotten three fig trees to grow 15 feet at the base of a red oak. They clearly love the free-draining soil, though the fruiting suffers from the shade.