UNITED STATES—Just about every home garden has some sort of shade. Even if there are no substantial trees or shrubbery, there are northern walls of homes and garages, and they likely have eaves that extend their shadows a bit farther. Fences to the south create shade to the north. Gardens of modern homes are smaller, and surrounded by higher homes and fences, so are shadier than older gardens.
Those who enjoy gardening tend to enjoy more trees and substantial shrubbery than those who do not enjoy gardening, so generally contend with more shade. It is both an asset and a liability. Cooling shade makes outdoor living spaces more comfortable in the heat of summer, but limits what we can grow. With very few exceptions that are not worth mentioning, all plants need sunlight.
Fortunately, many plants need less than others. Of these, many are understory species, which live in the partial shade of larger plants in their natural environments. Not only do they naturally need less sunlight, many prefer to be in partially shaded or sheltered situation. Their foliage and bloom can be scorched by sunlight if too exposed, especially while the weather is warm, windy or arid.
Plants that prefer partially shaded and sheltered situations are characteristically different from those that prefer more exposure. Their leaves tend to be bigger and darker green to absorb more sunlight. Those that are sensitive to frost may prefer shelter from evergreen shade. To compete for pollinators with bloom above, flowers may be either bigger and more colorful, or more fragrant.
There are, of course, many exceptions. Ferns are probably the most familiar foliar plants for shade, but provide no bloom. Cast iron plant is comparable to fern for providing rich green foliage, but with insignificant bloom. Caladium, coleus and hosta are grown for lush foliage that is strikingly colorful instead of rich green. Hosta contrarily blooms with pastel flowers that are not even fragrant.
Kaffir lily, calla, hydrangea, azalea, rhododendron and impatiens provide more color for partial shade.
Highlight: Western sword fern
Within its natural range on the West Coast between the southern extremity of Alaska and the southern extremity of California, Western sword fern, Polystichum munitum, is the most common of the native ferns. A few disjunctive wild colonies live as far inland as the Black Hills of South Dakota. Yet, with few exceptions, Western sword fern is difficult to cultivate outside of the natural range.
A fern that is so resilient and undemanding seems like it should be more adaptable. Although foliage is fuller and richer green with regular watering and occasional fertilizing, established plants do not need much at all. They survive in the wild here, with naturally limited rainfall, and just go dormant if they get too dry. Symbiotic soil microbes might be their limiting factor in foreign regions.
The dark evergreen and pinnately compound fronds get about two or three feet long, but can get more than four feet long in damp and partly shady situations. They form thick mounds that mostly obscure lower old fronds that die after their first or second year. Since it is naturally an understory species, Western sword fern prefers somewhat rich soil, partial shade and shelter from dry wind.
Horticulturist Tony Tomeo can be contacted at tonytomeo.com.