Tips for Planting Grass in Clay Soil

Hard clay soil is the bane of home owners and gardeners who want nothing more than a green turf to call a lawn. Grass is an ideal ground cover because it is soft enough to sit on, yet hardy enough to withstand foot traffic. Unfortunately, soft, lush, green grass does not grow easily in soil with a high percentage of clay. Nonetheless, there are several tricks for transforming a dusty patch of hard clay dirt into an inviting, grassy yard.

The first step is to test the pH of your soil. Most grasses grow best in a soil that is slightly acidic, with a pH between 6 and 7. If the soil is too acidic, with a pH below 6, then you can add lime to the soil to raise its pH. Lime is the common name for calcium carbonate; lime for gardening use comes in the form of ground limestone, dolomite limestone, or pelletized limestone. When you buy a bag of lime, it will tell you how much to apply to your lawn according to your soil's pH.

If your soil is too alkaline, with a pH above 7, you can make it more acidic with sawdust and peat.

The next step is to till the soil to break up the hard deposits of clay. Hard clay inhibit grass growth because grass roots are not as long and strong as most weed roots. Tilling the soil helps aerate the ground, and grass grows well in less compact soil.

Add topsoil mixed with grass seed on top of the tilled clay soil, about an inch. It is possible to add topsoil over clay without tilling the clay first. However, you will need to add much more topsoil to get the same grass growing results, about 2 or 3 inches.

Along with topsoil, you can add mulch, compost, manure, and gypsum. Organic matter provides nutrients to the grass, while gypsum helps to break up soil particles and aerate the top layer of soil.

Plant grasses that grow well in clay soil. Bermuda grass is one of the most hardy warm season grasses, while bluegrass is a cool season grass that tolerates clay well. Keeping grass clippings on your lawn can help promote grass growth in clay soil. Just keep the amount of grass clippings in check, or you could develop a thatch problem.

Mix grass seed with clover seed to encourage grass growth in clay soil. Clover has long roots that can break up hard chunks of clay, plus clover brings necessary nitrogen to the soil. Clover can even be used as a grass alternative for soil with a really high percentage of clay. One of its main advantages is that it doesn't need to be mowed, since it cannot grow very tall. The main disadvantage is that it doesn't hold up to foot traffic very well. Something that can be either an advantage or disadvantage (depending on your viewpoint) is that clover attracts bees like crazy.

Avoid overwatering your lawn. Too much water will make the clay more compact, and grass tends to "drown" if the soil does not have enough aeration.

Give your lawn time. Grass won't grow in tough clay soil overnight. It can take many months, or even whole seasons for the conditions to change so that they favor grass. Try to establish a cover crop, such as clover, and then introduce grass when the cover crop has improved the soil.

© Had2Know 2010