Work out how much grass seed to buy, the best window to sow it, how long it takes to come up, and exactly how to water it in until it is established.
About this tool: how much grass seed do you need? Guide: seeding and overseeding a lawnThe Rest of the Lawn
How much nitrogen your grass wants over a year, split into feedings that land in the 0.5 to 1.0 lb window, in pounds of the bag you actually own.
Open the calculatorInches a week for your grass, season and soil, turned into days a week, minutes per zone, and cycle-and-soak splits that stop runoff.
Open the calculatorWhether the lawn needs lime at all, and how many bags of which kind if it does, worked out without a soil test.
Open the calculatorSeed size varies by an order of magnitude, so rates do too. Pounds per 1,000 sq ft:
| Grass | New lawn | Overseeding |
|---|---|---|
| Kentucky bluegrass | 2 to 3 lb | 1 to 1.5 lb |
| Perennial ryegrass | 6 to 9 lb | 4 to 5 lb |
| Tall fescue | 6 to 8 lb | 3 to 4 lb |
| Fine fescue | 4 to 5 lb | 2 to 3 lb |
| Bermuda (hulled) | 1 to 2 lb | 0.5 to 1 lb |
Extension mid-ranges (Penn State, NC State, Purdue). More is not better: sown thick, seedlings compete and you get a weak mat that thins out anyway.
Cool-season: late summer into early autumn, by a wide margin. Warm-season: late spring once soil is reliably 65 to 70 °F. Soil temperature beats the calendar, so buy a thermometer.
Seed on thatch does not germinate. Mow short, rake to expose soil, cover to a quarter inch. Below half an inch most never surfaces.
Light and frequent, keeping the top inch damp, often twice a day. A seed that germinates then dries is dead. Taper to deep and infrequent after a few mows. Bluegrass can take 30 days, so do not reseed bare patches too early.
Most pre-emergents stop grass seed as effectively as weed seed. Siduron and mesotrione are the exceptions, but the label governs.