Soils that contain a large amount of clay particles present a problem for the gardener. Clay soils are dense, and don't allow water to drain, or air to get to the plant's roots. Adding organic matter to a clay soil is the best way to improve its texture and provide nutrients at the same time. For clay soil, you will need 2 cubic yards of amendment for a 100-square-foot garden. Amendment materials can be purchased in bulk and delivered to your home. Plan to amend your soil in the fall.
Dig up the top 12 inches of soil in the garden, turning it and crushing any large clods of dirt. Remove any rocks or other debris.
Spread a 6-inch layer of builder's sand and a 1-inch layer of compost over the existing soil. Mix together well, using the garden fork.
Level the planting area with a rake.
Add a 6-inch layer of wood chips over the top of the amended soil and water deeply. By spring, your soil should be ready for plants.