A common type of ground cover, grass makes a good surface for the activities of people and pets. It also protects the soil from erosion due to wind and water. Some types of soil pose a problem for lawn establishment and growth. The fine-knit particles of clay soil cause grass plants, as well as other types of plants, to struggle to obtain air and water. Heavy, clay soils compact around the roots of plants. Growing grass in clay soils requires amending and preparing the soil prior to planting, as well as caring for established grass.
Test the soil in your yard before planting your grass. Soil tests measure the amounts of nutrients present in the soil and the existing pH balance. In addition to the obvious porosity problems, clay soils often lack adequate levels of nutrients necessary for healthy lawns. Purchase any amendments recommended by your soil test results.
Loosen your clay soil with a rototiller. Do this on a dry day when soil is dry or just slightly damp. Do not attempt to work your clay soil when it is wet. Digging in wet clay will cause hard clumps to form in the soil and create an uneven, lumpy surface. Break up the top 5 to 6 inches of soil by going over your planting site numerous times until evenly tilled.
Spread the soil amendments recommended by your test results over the surface of the soil. Add organic matter, such as sphagnum peat, to loosen your clay soil and increase the porosity. Purchase sphagnum peat from your local nursery or gardening center. For heavy, clay soils, use about 3 cubic yards of peat for every 1,000 square feet of surface area in your yard. Spread the peat evenly over your planting site and mix into the underlying soil with your tiller. Go over the entire area two or three times, evenly mixing the soil with the amendments. Rake the surface to create a smooth bed for your lawn seed.
Plant your grass seed over the surface of your prepared soil with a seed broadcaster. Spread your lawn seeds at the rate specified on the seed bag. Run a soil roller over the surface of your scattered seeds to provide good contact between the soil and the seeds. Moisten the surface of the soil with a fine spray of water.
Water your new lawn as it germinates and grows, according to the instructions provided with your selected variety of grass seeds. Most types of grass seeds require steady levels of slight moisture during germination. Depending on your climate, this may mean light watering a few times every day for a couple of weeks.