Clay soil makes growing nearly any type of plant, including flowers, vegetables, trees and grass, very difficult. Clay soil won't drain properly, won't provide proper aeration to the plant, and can become so hard and compacted that roots won't be able to penetrate the soil. Although clay soil will never be perfect, it can be improved and made viable for planting.
Cultivate clay soil and remove large dirt clods. Use a garden fork to cultivate the soil to a depth of 8 to 10 inches, breaking up any large clods with the fork. Allow the soil to dry slightly so that the remaining clods are crumbly, then soften the clods with a fine spray of water. Rake the soil to smooth out remaining clods.
Improve the soil by incorporating 3 to 6 inches of decomposed organic material into the top 8 inches of the soil. Compost, well-rotted manure or leaf mold are all good choices, and will immediately improve drainage and aeration. Shredded bark, sawdust and straw can be used, but are slow to decompose.
Plant the improved area as desired. Water the area carefully. Avoid deep watering that will wet the soil beyond the newly-improved area, as the water may have difficulty moving freely from one soil type to another.