Shade Is Not Always Cool

Deep shade can be a problem.

Tall Victorian houses make long shadows. Lower ranch houses make shade with broad eaves. Awkwardly big modern homes shade more of their disproportionately small gardens than the others, especially since they have such tall fences to compensate for their minimal proximity to other homes. Even the sunniest of home gardens have some sort of shade.

Like various architecture, various shade trees make different flavors of shade. Silk tree, honeylocust and silver maple make broad shadows of relatively light shade. Because they are deciduous, they allow most sunlight through while bare in winter. Southern magnolia, Canary Island pine and Canary Island date palm make darker shade throughout the year.

Spots that are shaded only by the west side of a fence get warmer afternoon sun exposure than spots that get eastern exposure in the morning. Plants that are only shaded in the morning therefore need to tolerate both warm afternoon exposure and partial shade. Eastern exposures are easier to work with, since most plants that tolerate a bit of shade also like to be sheltered from harsh afternoon exposure.

Because fences lack eaves, southern exposures lack shade, and may enhance exposure by reflecting glare and heat. Southern exposure against houses and garages is determined by the height and width of the eaves. Light colors reflect more than darker colors. Northern exposures are of course the shadiest.

Whether for shade of sunny exposure, plants need to be selected accordingly. Bougainvillea, ceanothus and other plants that like good warm exposure with plenty of sunlight will not do much if shaded. Kaffir lily, hosta, rhododendron and various ferns that prefer partial shade can get roasted if too exposed when the weather gets warm and dry (with minimal humidity).

Eastern redbud, sweet bay, Oregon grape, Heavenly bamboo (nandina), various hollies, various podocarpus and both English and Algerian ivies are some of the few plants that are not too discriminating about their exposure, and will be just as happy with partial shade as with full exposure. Hydrangea, camellia, fuchsia and aucuba are nearly as agreeable, but will get roasted by harsh exposure enhanced by reflected glare from walls or pavement. All palms tolerate shade while young, but adapt to full exposure as they grow above what shades them.

Shade can change as the environment changes. Sun exposure increases if a tree or building gets removed. Remodels or newer and higher fences can increase shade. Even without such obvious modifications, large shrubbery and trees make more shade as they grow.

Shade Can Be An Asset

90911thumbJust 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 and 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.

Rain On The Shade Parade

60622thumbModern urban lifestyles are becoming less conducive to gardening all the time. Bigger and taller homes cast larger shadows over smaller garden spaces. The taller fences between these homes do not help. The densely evergreen trees employed to obscure the views of other larger and taller homes also obscure sunlight. Not much sunlight reaches the ground where shorter plants need it.

While all this is going on, we are supposed to be gardening with more sustainable plants that demand less water. Smaller, shadier and more sheltered gardens should naturally use less water than larger and more exposed gardens need. Yet, the plants that do not mind the shade naturally want more water than plants that want more sunlight. There are not many that are drought tolerant.

Drought tolerant plants are naturally endemic to dry climates. Many are from chaparral regions. Some are from deserts. In such ecosystems where water is too scarce to sustain much foliage, there is not much competition for sunlight. Shade tolerant plants are just the opposite. They are from forested ecosystems with taller and shadier trees. Such ecosystems are sustained by rainfall.

There are quite a few plants that do not mind a bit of shade. Heavenly bamboo, flowering maple, hydrangea, camellia, azalea, rhododendron, holly, daphne and andromeda (Pieris spp.) are some of the more familiar shade tolerant shrubbery; but alas, none are drought tolerant. Nor are the various ferns. Even small shade tolerant trees like dogwood want to be watered regularly.

Most of the plants that tolerate shade but are not too terribly thirsty are groundcover plants or perennials. They are not exactly drought tolerant, but can survive with minimal watering because they do not dry out so much in the shade. Once established in a cool shady environment, plumbago, lily turf, periwinkle Saint John’s wort and coral bells (Heuchera spp.) only need to be watered occasionally through summery weather, although they are thirstier in sunny spots. Both English and Algerian ivy need nothing in the shade.