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How to Improve the Tilth of Clay Soil

By Bridget Kelly ; Updated September 21, 2017

Clay soil presents a host of problems for the gardener. Clay compacts easily, cutting off oxygen to plants’ roots. It also has poor drainage, holding water for long periods. Clay soil tends to be saltier than other soils as well. Managing clay soil is important to your garden's success. The tilth of the soil, its physical condition as it relates to supporting plant life, is an aspect that merits close attention and, with clay soil, a lot of work. Clay soil may take years to fully amend.

Dig into the soil to a depth of 10 inches with a shovel. As you dig, turn the soil over and crush it with the shovel or gardening fork. If the soil is moist, wait until it is dry to work on it, as working wet clay soil causes it to compact.

Add a 4-inch layer of shredded bark and a 4-inch layer of compost to the existing soil. Mix the amendments into the top 4 inches of soil. Rake the area until it is level.

Spread a 4-inch layer of wood chips over the top of the soil. Do not mix the chips into the soil, but allow them to sit over the winter. They will break down and help aerate the soil.

Till the soil in the spring, as soon as the ground has thawed enough to work and the soil is dry. Dig the wood chips into the soil to a depth of 10 inches.

Spread a 3-inch layer of compost over the area and mix it in to a depth of 6 inches. The tilth of the soil should be amended enough to allow you to plant.

Spread a 4-inch layer of wood chips over the area again, each winter, and allow them to overwinter on top of the soil.


Things You Will Need

  • Shovel
  • Gardening fork
  • Bark
  • Compost
  • Wood chips
  • Rototiller

About the Author


Based in the American Southwest, Bridget Kelly has been writing about gardening and real estate since 2005. Her articles have appeared at Trulia.com, SFGate.com, GardenGuides.com, RE/MAX.com, MarketLeader.com, RealEstate.com, USAToday.com and in "Chicago Agent" magazine, to name a few. She holds a Bachelor of Arts in English with a concentration in creative writing.