The best time to plant grass seed depends on the kind of grass. Cool-season grasses such as tall fescue, Kentucky bluegrass and perennial ryegrass do best when seeded in late summer to early fall, roughly mid-August to October depending on how far north you are, with late winter to early spring as a second choice. Warm-season grasses such as bermuda, zoysia and centipede are seeded in late spring and early summer, once the soil 4 inches down stays at 65°F or warmer. The tables below collect the dates university extension services give for different parts of the country.
Once you know when, the grass seed calculator works out how much seed to buy for your lawn.
Cool-season or warm-season grass?
Lawns in the northern half of the US, from New England and the Midwest to the Pacific Northwest, are mostly cool-season grasses: tall fescue, Kentucky bluegrass, perennial ryegrass and fine fescues. Lawns across the South use warm-season grasses: bermudagrass, zoysiagrass, centipedegrass, St. Augustinegrass and bahiagrass. In the transition zone between them (for example Kentucky, Tennessee, Virginia and North Carolina), tall fescue is common, alongside zoysia and bermuda. If you are not sure what you have, a seed label from the original lawn or your county extension office can tell you.
When to seed cool-season grass
| Area (source) | Best time | Second choice |
|---|---|---|
| Northern Indiana (Purdue) | Aug 15 to Sep 15 | |
| Southern Indiana (Purdue) | Sep 1 to Sep 30 | |
| Maryland (University of Maryland) | Mid-August through October | Mid-February through March |
| Kentucky (University of Kentucky) | Mid-August to late September | Mid-February to mid-March, no later than mid-April |
| Tennessee (University of Tennessee) | Late August to mid-October | Not for Kentucky bluegrass in spring |
| Georgia, tall fescue (University of Georgia) | September to October | Late February to March, Mountain and Piedmont regions |
Fall seeding gives seedlings warm soil to germinate in and cooling weather to grow in, and a full fall and spring to root before summer heat. Timing within the window matters: Purdue notes that waiting one week later can mean the new lawn takes two to four additional weeks to mature, so seed early in your window rather than late.
When to seed warm-season grass
| Area (source) | Seeding window | Trigger |
|---|---|---|
| Georgia (University of Georgia) | May to June, no later than early to mid-August | Soil at 4 in consistently 65°F and rising |
| Kentucky (University of Kentucky) | Late May or June | Night air temperatures consistently above 60°F |
| Tennessee (University of Tennessee) | May 1 to June 30 |
Warm-season grasses need hot weather to germinate and grow, so seeding them in early spring or fall wastes seed. Seeding by early to mid-August at the latest leaves time for the grass to establish before it goes dormant. St. Augustinegrass is the exception: LSU AgCenter notes that no commercial St. Augustinegrass seed is available, so it is established from sod or from plugs set about 1 ft apart.
How long does grass seed take to germinate?
| Grass | Days to germinate |
|---|---|
| Perennial ryegrass | 3 to 7 |
| Tall fescue | 6 to 12 |
| Kentucky bluegrass | 14 to 21 |
| Zoysiagrass (Zoysia japonica) | 10 to 14 |
| Bermudagrass, hulled | 10 to 20 |
| Centipedegrass | 10 to 20 |
These are times under good conditions: moist seedbed, seed in contact with soil, and suitable temperatures (the same publication gives air temperatures of about 59 to 82°F for cool-season and 68 to 95°F for warm-season grasses). Seed sown at the edge of its window, in dry soil, or lying on thatch takes longer or fails. Mixtures germinate in stages, so a bluegrass blend can look patchy for the first two weeks while the ryegrass is already up.
Spring seeding: what to watch for
- Spring-sown cool-season grass has only a few months before summer heat and drought, so expect to water more and accept some thinning. The University of Tennessee advises against seeding Kentucky bluegrass in spring.
- Most crabgrass preventers stop grass seed from germinating too. Check the label for the waiting period before seeding, or use a product labeled for use at seeding.
- Seed as early in the spring window as the soil can be worked, rather than in late spring.
How much seed?
Seeding rates differ for a new lawn and for overseeding, and by grass. Grass seed rates: new lawns vs overseeding has the rates per 1,000 sq ft, and if you want an instant lawn instead, see sod rolls, slabs and pallets.
Frequently asked questions
How do I check soil temperature?
Push a soil thermometer about 4 inches into the ground, the depth the University of Georgia uses for its 65°F rule, and read it for a few mornings in a row. Your state extension service may also publish soil temperature readings.
Can I seed bermuda or zoysia in the fall?
Not as a new lawn. Warm-season seed needs warm soil, and late-sown seedlings may not establish before the first frost. Georgia gives early to mid-August as the latest date.
Is it too late to seed in October?
In the northern US, mid- to late October is usually late for a new lawn, because seedlings need several weeks of growth before the ground freezes. Farther south, such as Tennessee and Georgia, October is still within the published window for tall fescue.
Sources
- Purdue Turf: Now Is the Time to Seed Cool-Season Turf (seeding windows for northern and southern Indiana)
- University of Maryland Extension: Poor Seed Germination in Lawns (best and second-best seeding times, germination days)
- University of Kentucky AGR-50: Lawn Establishment in Kentucky (cool- and warm-season seeding dates)
- University of Tennessee W160-F: When to Plant Turfgrasses (planting windows for Tennessee)
- University of Tennessee W160-B: Turfgrass seeding (days to germinate by species, temperature ranges)
- University of Georgia B1533-2: Lawns in Georgia: Establishment (seeding dates, soil temperature, first watering and mowing of sod)
- LSU AgCenter Pub. 3624-SS: St. Augustinegrass (establishment by sod or plugs)
