Gray clay soils are characterized by shallow topsoil, are prone to compaction and have poor drainage. These soils can be either acidic or alkaline. Gray clay soils are full of various nutrients, but many plants have a hard time establishing their root systems in these dense soils and often become waterlogged. To successfully grow most plants, you need to amend such soil and improve its consistency so that you create a fertile growing medium.
Dig the tines of a rake or rototiller into the soil, working to 8 inches deep until the soil is loosened. Work in rows, turning at the end of each row and continuing down the next row to the opposite end.
Sort through the soil by hand to remove weeds and rocks.
Perform a soil test, using a kit purchased from a gardening center, to test the pH. Sample four different areas of the soil, mix these together and test the combined soil.
Dig lime or sulfur into the soil, depending on the results of the soil test. Add lime if the pH is too low or sulfur if the pH is too high. Till the amendment in, working to a depth of 8 inches. Continue testing and gradually adding lime or sulfur until the test results show you have reached the desired level.
Empty bags of compost or manure into a wheelbarrow. Shovel the compost or manure onto the top of the soil until it forms a 3-inch layer. Till the new layer into the existing soil.
Rake the garden area until it appears level. Water the soil until it is well saturated.