Clay soils warm up slower in spring and compact if worked when wet. Each of these problems will retard root development and plant growth. There are many prairie plants that can grow in clay soils. With good initial care, these flowers and grasses will flourish even on difficult sites. Their roots will gradually work their way down into the clay, opening and improving it, just as these plants have done for thousands of years.
Soil moisture is equally important in deciding what species to plant.
Moist soils have a generous amount of water in the subsoil throughout the growing season. They may have periods of standing water in the spring or fall. Dry soils include sandy and gravelly soils that drain readily and never have standing water, even after a heavy rain. These soils may have standing water for short periods after a hard rain. Aged compost can be worked into the soil at planting time or added as a surface mulch any time.