How to Amend Clay Soil for Organic Gardening


Clay soil offers many problems to gardeners. It is water retentive, drains slowly and compacts to rock form when dried. Because of these issues, many plants cannot be safely grown in clay soil. Cacti rot and weak rooted plants cannot spread through the rock like soil. There is hope for gardeners with clay soil. This heavy substance can be broken up and made into a lighter growing medium with only a few supplies.

Step 1

Choose a dry day when the soil is not too dry or wet. Remove all large debris and rocks from the area. Dig out stumps and roots with the shovel. Till the area thoroughly as deeply as possible. It may take several runs. With the tiller set on the highest setting, make one pass through the area. For each additional tilling, set the blades lower, until the last pass is at the lowest setting. Rake the area level, and check for large masses of clay. Break the clods of soil up with the shovel and rake.

Step 2

Spread a thick layer of compost on the entire area to be amended. Till this layer in well. Broadcast the bark mulch and fertilizer evenly across the clay before tilling it in. Till this mixture until the organic matter is evenly distributed throughout the soil. If the soil needs acidifying, apply cottonseed meal as per the manufacturer's recommended dosage. Break up any large clumps found, and rake them level with the soil.

Step 3

Wet a patch of soil and squeeze it between your hands. It should form a ball that holds together but is easily broken up. If when the wet soil is squeezed it feels like paste and is hard to break up, add and till in additional organic matter.

Tips and Warnings

  • Always keep a firm grasp on the tiller as it can hit a rock and throw you. Never try to till over large items like rocks or roots. Always wear gloves and high impact safety glasses when working with a tiller. Walk on the soil as little as possible after it is tilled. Too much foot traffic will compact the clay.

Things You'll Need

  • Shovel
  • Tiller
  • Rake
  • Gloves
  • Safety glasses
  • Bark mulch
  • Compost
  • Organic fertilizer
  • Cottonseed meal


  • National Cottonseed Products Association: Cottonseed Meal
  • Fine Gardening: Improving Clay Soils
Keywords: how to amend clay soil, clay soil problems, organic clay gardening

About this Author

Izzy McPhee has been a freelance writer since 1999. She writes about gardening, child care, family, living on a budget and do-it-yourself projects. Her paintings have appeared in the well known gallery The Country Store Gallery in Austin, Texas. Her work can be seen on and Demand Studios.