There’s a good chance, as you plan your shade garden, that the image you have in mind is that of a moist shade garden, probably because shaded areas are damp in many cases. Where there’s little sun, there’s little moisture evaporation.
Moisture lovers include pond-dwelling water lilies, which rely on the oxygen and nutrients in water to thrive.
Photo Credit: ©2000 Dolezal Publishing/Tim Butler
The localized humidity provided by a garden fountain creates a perfect environment for these moisture-loving shade plants.
Photo Credit: ©2000 Dolezal Publishing/Charles Slay
Orchids may require regular misting to maintain the high humidity level they crave.
Photo Credit: ©2000 Dolezal Publishing/Charles Slay
Many groundcovers, like Bacopa (here growing in a raised bed), don’t require heavy watering or even constant moisture to thrive.
Photo Credit: ©2000 Dolezal Publishing/Yvonne Williams
Vining groundcovers, like Vinca minor, spread to find the light and moisture they need.
Photo Credit: ©2000 Dolezal Publishing/Yvonne Williams
Moist shade isn’t confined to woodland settings. It can occur in areas of open shade created by tall buildings, along fences and walls, and under patio covers. Moist shade is a gracious host to many shade-loving plants and shrubs, such as hydrangeas and azaleas, most mosses and ferns, impatiens, phlox and primroses, to name just a few. When planted in rich, loose soil, a moist shade garden can enjoy great success and add a splendid touch of coolness to your yard in summer.
If these are the plantings you crave, realize that it’s easy to revamp dry shade areas by installing an inground irrigation system. A number of today’s home irrigation systems provide multiple options for getting water to your plot – but you’ll need to be vigilant with your watering regimen. Too much water will cause many moist-shade plants, such as impatiens and most bulbs, to develop fungal disease. Adding pachysandra or bugleweed to the mix will help retain moisture. In addition, you’ll need to monitor moist garden areas for poor air circulation, which can go hand in hand with shady corners of a yard – particularly if the yard slopes downward. Clearing away low-growing shrub and tree branches will go a long way toward improving airflow.
Dry shade areas are as conducive to planting as moist ones. Create dry shade with certain trees and shrubs, especially shallow-rooted and heavy feeders such as conifers, beeches and Norway maples, which can suck moisture out of the ground and away from tender-rooted perennials and annuals. Alternatively, use wide-roof eaves and patio-cover extensions that block rain from reaching the ground to create a dry-shade area. In addition, dry shade can be created in areas where the soil drains too quickly or the ambient air is hot.
You can correct for this condition by deep digging and incorporating large doses of amendments, or by using raised beds or containers with " drip irrigation systems or overhead misters that mount on trees and create humidity. The best solution always is to adapt your plantings to suit the site. Not all shade-loving plants need constant heavy moisture to thrive. Certain epimediums, particularly Epimedium x perralchicum ‘Frohnleiten,’ tolerate dryness, as do the groundcovers barren strawberry, lunaria, lilyturf, Asian wood poppy, ribbon grass, spotted dead nettle, Vinca minor (periwinkle), aspidistra and sweet alyssum, among many others.
All dry shade plantings can benefit from some soil amendment with a moisture-retentive material such as peat moss, leaf mold or mushroom compost. If shallow-rooted trees and shrubs cause the dryness, you might add a slow-release nitrogen fertilizer to the amendments to help satisfy hungry roots and prevent them from spreading into the planting area. After planting, place a layer of mulch over the soil surface to hold in the moisture and help reduce the rate of evaporation.
Even desert-dwelling plants like – and can benefit from – some shade, at least during the hottest part of the day, especially in regions where “hot” means “really, really hot.” (Too much sun can scorch even the most heat-tolerant plants.) These types of plants are obviously suited for dry shade conditions. If you’d like to plant a desert garden in dry, existing shade, it will work best if the area receives sun for about half the day, particularly in the morning. If you’re planting in raised beds, desert plants tend to like a sandy potting mix of one-half compost and one-half pumice, perlite or volcanic rock that’s 1/8-1/4 inch in diameter. Fertilize these plants a little less in shade. Low-nitrogen liquid fertilizers and fish emulsion work well, but use them at one-quarter strength each watering.
