Starting a new lawn from seed: the soil, seedbed, mulch, watering and mowing steps extension pages give

What is a new-lawn establishment sequence?

A new-lawn establishment sequence is the ordered list of jobs an extension page gives between bare ground and the first mowing: soil test, grading, tilling, seedbed, seeding, mulch, watering and mowing. Kentucky's AGR-50 says the key is to do everything properly from the start so you do not have to fix the lawn once it is established.

This guide covers the steps and the cautions. It leaves out seeding dates and seed amounts, which have their own posts: cool-season and warm-season seeding windows and how much grass seed per 1,000 sq ft. Where the four pages are set side by side, the comparison is our reading, and each point names the page it comes from.

Soil test, grading and tilling

All four pages start with a soil test. Kentucky says that without one you are applying fertilizer blindly, and that the time before planting is ideal for adding large amounts of nutrients or lime without burning the lawn. Penn State says to collect samples three to four weeks before you begin preparing the soil. Maryland wants a laboratory test for pH, nutrients and organic matter, and calls lab tests more thorough and accurate than home kits. Rutgers says the results give lime and nutrient recommendations and points readers to the county extension office.

Grading comes next. Kentucky says to remove building debris from the whole lawn area and slope the subgrade away from the house. It calls 4 to 6 inches of good topsoil the goal. Penn State asks for a minimum of 4 to 6 inches of firmed topsoil and a slope away from foundations of 1 to 4 percent, and Maryland gives 1 to 2 percent. Maryland and Rutgers both warn against changing the grade around established trees.

Then the tiller. Kentucky, Maryland and Rutgers all work lime and fertilizer into the top 4 to 6 inches. Maryland, Penn State and Rutgers say not to till wet soil: Maryland says it damages soil structure, Penn State says to till moist soil in one or two passes, and Rutgers says wet soil leads to poor germination. Rutgers says that where a lime need runs past 200 lb per 1,000 sq ft, you work in half, apply the rest, and incorporate that too. Penn State keeps nitrogen out of the tiller and puts it on the surface as a starter just before or after seeding.

Seedbed, seeding and mulch

The seedbed has to be firm. Kentucky wants two or three good rains of 0.25 inch or more, or irrigation, to let the graded soil settle, and says puddles show low spots to fill before planting. Its final seedbed is firm and free of large clods, rocks and building materials. Penn State sets the stone limit at 2 inches across and firms the soil with a heavy mat, a light roller or a cultipacker when the soil is fairly dry. Rutgers rakes out stones and clods big enough for mower blades to hit.

Seeding itself follows one pattern on every page: split the seed in half and spread the halves in two directions. Maryland suggests setting the spreader to half the rate for each pass. Penn State drags a leaf rake lightly so about 1/4 inch of soil covers the seed, and Rutgers rakes the seed in about 1/4 inch deep. Kentucky rakes lightly or uses a water-ballast roller, because seed lying on top of the soil cannot reach water. Maryland covers seed with 1/4 to 1/2 inch of topsoil or finished compost.

Mulch is where the numbers differ most. Kentucky uses clean straw thin enough to leave about 50 percent of the soil showing, about one bale per 1,000 sq ft. Rutgers gives 50 to 90 lb of unrotted, weed-seed-free straw and says about 25 percent of the soil showing is usually enough. Maryland and Penn State both give 80 to 100 lb. Maryland says to avoid hay because it can carry weed seeds. Penn State warns that too much straw can smother seedlings and bring disease, and tells readers to remove the excess after establishment. Rutgers says to take some off after germination once seedlings have 2 to 3 inch roots.

Watering, fertilizer and the first mowing

Watering is light and frequent at first. Kentucky says to irrigate lightly and frequently until germination is complete, to keep the soil moist for two to three weeks, and to avoid puddles, which move seed and cut germination. Maryland puts about 1/4 inch on per session at the start and keeps the top inch moist. Seedlings may need watering several times a day for several weeks. Rutgers keeps the top 2 inches moist until germination and early root growth, then waters less often and more deeply, to 3 to 5 inches. Penn State says newly seeded turf will probably need regular, sometimes daily, watering, with the soil moist but never excessively wet.

Fertilizer waits a little. Kentucky puts none on after seeding until seedlings are about 1 inch tall, and says to water it in so it does not burn them. Rutgers cautions against fertilizing wet seedlings. Penn State warns that more than 1.5 lb of nitrogen per 1,000 sq ft can burn young turf, and its starter rate is 0.5 to 1 lb.

The first mowing comes earlier than many people expect. Kentucky says not to be afraid to mow a new lawn: wait until the turf is about a third higher than the intended height, so a 2 inch lawn is first mown at 3 inches. Maryland and Penn State use the same one-third rule, and Maryland puts the first mowing at 4 to 6 weeks under good conditions and says to keep the blades sharp. Penn State says to use a lightweight mower and gives no fixed wait. The Rutgers page gives no mowing height or timing.

Traffic and weed control come after that. Maryland keeps foot traffic off for at least a month after germination or until the first two mowings. Kentucky and Maryland hold herbicides until the grass has been mowed three times, and Maryland waits for four mowings before grassy-weed products. Penn State says new turf is very sensitive to herbicides, and Rutgers says to use only products labeled for newly seeded lawns. For the grasses these pages mostly cover, see tall fescue and Kentucky bluegrass, and use the lawn schedule by ZIP for timing.

Frequently asked questions

How deep should I till before seeding a new lawn?

Kentucky, Maryland, Rutgers and Penn State all say to work lime, fertilizer or organic matter into the top 4 to 6 inches. Maryland, Penn State and Rutgers also say not to till wet soil.

How much straw mulch goes on new grass seed?

Maryland and Penn State give 80 to 100 lb of straw per 1,000 sq ft. Rutgers gives 50 to 90 lb, and Kentucky uses about one bale, thin enough to leave about half the soil showing. Maryland says not to use hay.

How often should I water newly seeded grass?

Lightly and often. Kentucky says to keep the soil moist for two to three weeks without puddles, and Penn State says daily watering may be needed. Rutgers keeps the top 2 inches moist, then waters deeper once roots form.

When do I mow a newly seeded lawn the first time?

Kentucky, Maryland and Penn State say to mow when the grass is about one third taller than the cutting height, so 4 inches for a 3 inch cut. Maryland says that usually comes 4 to 6 weeks after seeding.

Can I put weed killer on a new lawn right away?

The pages say wait. Kentucky holds herbicides until the grass has been mowed three times, Maryland holds broadleaf products for three mowings, and Penn State says new turf is very sensitive to herbicides.