Is Your Grass Seed Taking Too Long to Sprout? Here Are 3 Ways to Speed Things Up
Fresh grass seed can take longer to sprout than the bag suggests, especially as fall cools off. A slow start is usually normal, and a few simple changes can help it along...
Fall is when a lot of homeowners get around to overseeding cool-season lawns. You rake out the thin spots, spread the seed and set the sprinkler going. Two weeks later, plenty of those patches still look like bare dirt, and it's tempting to blame the seed.
Chances are, the seed is fine. Anyone who has spent time seeding a lawn knows some grasses are just slow, and a couple of the usual fall picks can take weeks to show anything. Fall is still a smart time to seed, though. The ground stays warm from summer while the air cools off, and the rain usually picks back up.
Grab the bag and check what's in it. A blend might mix ryegrass, fescue and bluegrass, and those don't keep the same schedule. Ryegrass can be up in about a week, while bluegrass may take a month, so a new blend looks spotty at first. And green doesn't mean done – new grass still needs several more weeks to root in.
The rest happens underground. Cool-season seed generally won't germinate until the soil is above about 50 degrees Fahrenheit, and colder ground can leave it sitting there until spring. Push a soil thermometer (like this one from the Urban Worm Store) in to see where yours is. The seed also has to stay damp and reach dirt, not just rest on dead thatch.
The Best Grass Seed to Sow in Fall
Any lawn that slows down and browns a little in July, then greens back up when the nights cool off, is a cool-season lawn. Bermuda, zoysia and bahiagrass are the opposite; those warm-season grasses do better seeded in late spring or early summer, after the soil has warmed up.
Across the upper Midwest and other northern areas, the ground cools early, so the window runs from mid-August to mid-September and has usually closed by October. Farther south, in places like Tennessee, there's room to seed into mid-October. Anything sown late has less time to get established before the first hard freeze.
Perennial Ryegrass (Lolium perenne)
Perennial ryegrass is what you want when a bare spot has to look green before winter – a worn strip by the mailbox, let's say, or the patch where the dog cuts across the yard. It's often up in 5 to 10 days. Sow it early in the fall window. One option is Pennington Fairway Supreme perennial ryegrass from Lowe's, which comes in a 50-pound bag with fertilizer mixed in. It's at its best in cool, moist weather and doesn't take drought well. In the South, it mostly gets sown over dormant Bermuda for winter color, not as a permanent lawn.
Tall Fescue (Festuca arundinacea)
If your USDA Planting Zone is somewhere between Kansas and the Carolinas, your lawn may well be tall fescue already. Bluegrass struggles in those hot summers, but fescue's deep roots carry it through dry spells. Seed usually comes up within a week or two. GreenView turf-type tall fescue seed, available on Amazon, comes in 7-pound bags. Fescue grows in clumps rather than spreading, though, so thin spots won't fill in by themselves and need reseeding in early to mid-fall.
Kentucky Bluegrass (Poa pratensis)
Bluegrass asks for patience up front. It usually takes at least two weeks to sprout and can take closer to a month. Once it's up, it spreads by underground rhizomes into a thick, soft lawn that can fill worn spots back in. It does best where summers stay fairly cool. Get it down right at the start of your fall window. Home Depot stocks a 5.6-pound bag of Scotts Turf Builder Kentucky bluegrass mix.
3 Tried-and-Tested Ways to Speed Up Grass Seed Germination
Keen for your grass to get a move on? Look this way...
1. Improve Seed-to-Soil Contact
Get down and look closely at a patch that still hasn't come up. You'll often find the seed sitting on top of old thatch or dead leaves instead of on the soil. It dries out between waterings up there; indeed, its first root may never reach the soil. Before you seed, mow the grass you already have down to about 1 1/2 to 2 inches (4–5cm), rake out the loose debris, then scratch up the surface until you can see bare, crumbly soil.
On small areas, a stiff 16-tine steel bow rake like the one Walmart carries will break up a crusted surface. Once the seed is down, rake over it lightly to work it into the top 1/8 to 1/4 inch (3–6mm) of soil, or press it in with the back of the rake. Don't worry if some seed is still showing, since bluegrass actually sprouts better with a little light.
2. Keep the Seedbed Consistently Moist
On a breezy afternoon, soil watered at breakfast can be pale and crusty by the evening. Seed that's begun to swell can dry out and fail. Short, light sprinkles once or twice a day, and one more on days like that, keep the top inch (2.5cm) damp, not muddy. Long soaks can float seed into low spots or waterlog the soil, and an overnight rain counts as a turn.
A pulsing impact head can knock seed loose, but an oscillating sprinkler lays water down in a soft sweep. With the Melnor XT turbo oscillating sprinkler from Amazon, you can narrow the spray so it stays on the seed, not the sidewalk. For days when nobody's home, the Orbit single-outlet hose faucet timer from Home Depot can run short cycles as often as once an hour. Once seedlings have roots, water less often but more deeply.
3. Add a Light Top Dressing
A thin layer of screened compost over the seed helps keep the surface from drying out so fast. That layer gives the seed some protection from heavy rain, too. Spread it no more than about 1/4 inch (6mm) deep. You should still be able to see a little seed and soil through it.
Thicker isn't better. Grass seed carries only a small store of energy, and seed buried too deep can use it up before the shoot reaches light —, and fine bluegrass seed may not sprout under a heavy layer at all.
If you don't have finished compost, a bag of Scotts Turf Builder lawn soil from Home Depot is made for overseeding and top dressing.
Shop Top Soil:
So how long should you wait? With ryegrass or tall fescue in soil that's stayed warm and damp, about three weeks is a fair wait. Before reseeding, scrape back a little soil and look. Swollen or split seed is still working, while seed that looks dry and unchanged probably dried out or never touched the soil. Old seed can be the culprit too, so check the packaging date.
Don't count on starter fertilizer to hurry any of this along. Seed carries its own food for germination, and starter fertilizer is there to feed seedlings once roots form – too much can burn tender new grass. If your fall window has closed, it's better to stop than to keep sowing into cold soil. Some people dormant seed instead, spreading it in late fall once the soil is too cold for sprouting but before the ground freezes. Otherwise, early next fall is the more reliable time to try again.
Slow grass seed usually just needs a few more weeks. Choose the right grass for your area, sow it while the soil is still warm, and keep it damp. That will do more than any quick fix. With some patience, those bare spots may be filled in by the time you mow next spring.
