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Plants for Damp Clay Shade

Plants for Damp Clay Shade

Plants for Damp Clay Shade

Clay is made of minuscule particles that trap water around delicate plant roots, leaving little space for oxygen, which roots need. Wet clay soil is often heavy and sticky, but once it dries, it tends to crack and form a crust, making it difficult to cultivate. Without organic material, such as compost or shredded leaves, clay soil becomes compacted. Plants that thrive in clay tend to have soil-busting root systems that can handle the compaction. A few examples are baptisia, bee balm (Monarda), hosta, sedum, coneflowers and Joe-pye weed. Many shrubs including Diervilla, elderberry, potentilla, flowering quince and Rose of Sharon tolerate clay, but you can make the soil more plant-friendly by adding compost.

Plant

Swamp milkweed (Asclepias incarnata) is a native prairie plant that thrives in roadside ditches and in open spaces. In its native habitat, this milkweed grows in marshes, wet fields, and shorelines throughout Illinois. However, it readily performs in average garden soil, and if it’s moist, that’s even better. A bonus: it provides nectar for many beneficial insects and is a host plant for monarch butterflies. Pasture rose (Rosa carolina), Virginia sweetspire, black chokeberry, dwarf fothergilla, and bush cinquefoil are small shrubs (less than 5 feet tall) that also tolerate moist, sunny sites.Some garden designers are creating perennial borders that contain a substantial layer of gravel at the surface. For gardeners who have spent years amending the soil and applying mulch, growing in gravel seems counterintuitive. However, the gravel layer prevents weed seeds from germinating and provides exceptional drainage—desirable attributes when growing many native prairie plants or perennial herbs like lavender that need well-drained soil. In Illinois, gravel prairies occur on kames and eskers (mounds and ridges of gravel deposited by melting glaciers). Charming native plants found in gravel prairies include little bluestem, side-oats grama, pasque flower, prairie smoke, fringed puccoon, shooting-star, blazing-star, prairie dropseed, prairie cinquefoil, sky-blue aster, prairie gentian, purple coneflower, rattlesnake master, silky aster, and hoary vervain. Their deep roots reach well beyond the rocky layer into the soil below.

One of the most difficult growing conditions is under tall shade trees. A healthy 100-foot-tall tree uses thousands of gallons of water, in a single growing season, so you’ll need plants that can adapt to dry, shady conditions. The tree’s root system is generally in the top two to three feet of soil and spreads far beyond the drip line—the edge of the outer leaves. It’s rather difficult to grow lawns under big trees and the result is usually sparse grass. A shallow layer of mulch from the trunk to the drip line is one solution, but gardeners like plants. Alternatives to lawn include shade-loving perennials such as hostas, sedges, hellebores, and barrenwort (Epimedium). When first planted, all of these perennials need adequate water during the growing season to establish healthy root systems. Consider adding some spring-blooming native wildflowers, such as Canadian ginger, bloodroot, bleeding heart, and columbine, as well as smaller daffodils like February Gold.A low spot in the garden can collect and hold water after a heavy rain. If the soil is primarily clay, it can take hours, if not days, for the water to drain away. Consider planting a rain garden in that area. The Chicago Botanic Garden's Rainwater Glen features native perennials with deep roots—marsh blazing star, spotted Joe-pye weed, great blue lobelia, and a variety of rushes and sedges, all of which tolerate rainfall fluctuations. And, the Garden has a rain garden how-to-manual just for you. (Source: www.chicagobotanic.org)

 

 

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