Q. My garden soil is hard and the plants don’t seem to grow as well as they should. What can I do?

A: Many new Colorado gardeners complain, “You can’t grow anything here”. Many plant problems are caused by soil conditions, which contribute to 80% of all plant disorders in the landscape. Gardening in Colorado can be a challenge due to poor soil tilth. A soil with good tilth has large pore spaces for adequate air infiltration and water movement. The “text book” soil is composed of 45% mineral solids, 25% air, 25% water and 5% organic matter. Along Colorado’s Front Range, many soils are clayey, compacted and naturally low in organic matter (less than 1%).

Gardeners can improve their soils by adding organic soil amendments to improve soil aeration, water infiltration, water and nutrient holding capacity and provide a better environment for plant roots. Organic amendments include compost, sphagnum peat moss and grass clippings. Gardeners can improve their soil by thoroughly mixing 3 cubic yards of organic amendments per 1,000 square feet, into the top six to eight inches of soil. As the soil organic content builds in a garden soil, the application rate should be reduced. A soil test is suggested every four to six years to establish a base line on soil organic matter.

For more information on soil amendments and soil testing, see Colorado State University Cooperative Extension Fact Sheet #7.235, “Choosing a Soil Amendment” and Fact Sheet #0.501, “Soil Testing” or contact your local Cooperative Extension office.

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This page updated:  April 18, 2007