How to Plant Vegetables in Clay Soil

Overview

All soils are made up of three elements: silt, sand and clay. Loam soil is a fairly equal mix of the three and has a texture like chocolate cake, soft and easily worked. Clay soil, on the other hand, has a texture more like cement, especially when it is wet.You probably have clay soil if your soil clumps together when worked or you can mold it into ribbons when you roll it in your hand. Understanding the attributes of clay soil is important for gardening success. Clay soils hold water and nutrients well, but lack oxygen and are often cold.

Step 1

Cut open the bale of peat moss with a knife. Spread the peat moss on a tarp and wet thoroughly with a garden hose until the peat moss is moist, but not soaking. Peat moss is hard to moisten once you've tilled it into the ground and wicks moisture out of the soil.

Step 2

Lay 3 inches of compost, manure and peat moss on your soil in equal amounts. Shovel the soil amendments into the soil, digging to a depth of 8 inches.

Step 3

Lay a sheet of clear plastic on the soil three weeks before you plan to plant. Clay soils warm up slowly in the spring, but laying plastic down can raise the soil temperature several degrees in just a few days.

Step 4

Plant cool-season vegetables such as lettuce, carrots, broccoli and onions four weeks before the last expected frost. Plant warm-season vegetables such as tomatoes, corn and peppers after the last expected frost. Consult your local county extension office for varieties that grow well in your clay soil. For example, buy half-long carrot seeds because long carrots don't grow well in heavy clay soils.

Step 5

Plant seeds slightly more shallowly (1/8 to 1/4 inch) than indicated on the seed packet because the heavy clay soils make germination difficult. Loosen the soil with your shovel when digging holes for transplanting vegetable plants.

Step 6

Water vegetables slowly with a trickling hose or soaker hose. Clay soils become waterlogged quickly, causing problems such as blossom end rot on tomatoes. Only water when the soil feels dry 3 to 4 inches under the surface.

Tips and Warnings

  • Never work clay soil when it's wet. You'll compact the soil even further, resulting in a hard, concrete-like mess.

Things You'll Need

  • 1 bale peat moss
  • 1 bag compost, 40 quarts
  • 1 bag manure, 40 quarts
  • Shovel
  • Vegetable seeds and plants

References

  • Colorado State University Extension Office: Choosing a Soil Amendment
  • Colorado State County Extension Office: Vegetable Garden Hints
  • "The Garden Primer;" Barbara Damrosch; 1988

Who Can Help

  • Washington State Extension Office: Home Gardens
Keywords: clay soil gardening, vegetable gardening, improving clay soil

About this Author

Julie Christensen has been writing professionally since 2001. She is a full-time freelance writer and former teacher with writing credits from several regional and national publications, such as Colorado Parent and LDS Living. She specializes in parenting, education and gardening topics. Christensen studied early childhood education at Ricks College, and spent 20 years as a teacher and director in university and public school settings.