No gardener likes working with clay soil. It's rock hard in dry weather and a soupy, sticky messy in wet weather. Since most plants prefer fertile, well-drained soil, very few plants will thrive in heavy clay soil. Luckily, gardeners do have a few choices when it comes to flowers, vegetables, trees and shrubs. You can also work compost or peat moss into the soil and add mulch to your garden to improve the drainage and fertility and increase your options.
Rose bushes have a robust root system that can tunnel through dense clay, although if your clay soil is lacking in organic material you may have to work in compost or apply fertilizer. Many wildflowers native to North America are naturally adapted to bust through clay soil, and they add beautiful blooms to your garden while providing food and habitat for local wildlife. Some wildflower to consider include native asters, coneflower, black-eyed Susan, coreopsis, false indigo and silphium.
While most food crops need a higher quality soil to grow healthy fruits and vegetables, a few vegetables can adapt to clay soil. Most root crops or tubers will be stunted in dense clay soil, but potatoes are tough enough to break through the clay. Many brassicas, such as kale, cabbage or broccoli, can grow in clay soil, but they do best if planted as a fall crop, after the soil is thoroughly warm. Consider planting legumes, like beans or peas, to fix nitrogen in the soil and improve the fertility.
Trees and Shrubs
When planting trees and shrubs in clay soil, dig a hole that is as deep as the root ball and twice as wide. Build a small mound in the middle to spread the roots over, and backfill the hole with a mixture of two or three parts original soil and one part compost or peat moss. Don't backfill the hole with rich black soil or use too much compost or peat moss, or else the roots may just spiral around through the good soil and eventually strangle the tree. Some shrubs and small trees that do well in clay soil include serviceberries (also called shadblow, saskatoon or juneberries), red osier dogwood, chokecherries, lilacs and wild currants. For taller trees, consider silver maple, river birch, black ash, tamarack (also called larch), basswood (also called linden) and willows. While most fruit trees prefer well-drained soil, some species of apple or pear trees may tolerate growing in light clay.