A warm day is a day with soil at that temperature or warmer. Each temperature is what the cited source gives for good germination. For most cool-season grass that is the low end of the best range, not a hard minimum. The sources measure soil about 1 to 4 inches down. The tracker's soil model reads about 2.4 inches (6 cm). St. Augustine and kikuyu go in as plugs or sod. Bahia, zoysia and carpetgrass seed aren't tracked yet because we couldn't find a sprout time to cite.
Grass seed not coming up?
First check the cold days in your tracker. If the window has passed, go down this list.
Is the top inch damp?
New seed needs the surface kept moist. Water in short bursts 2 to 3 times a day until sprouts show.
Is there a crust?
Check bare spots for dried, crusted soil. A light rake and a few days of surface watering often brings up seed that was there all along.
Is the seed touching soil?
Seed that sits on thatch dries out. It needs to be raked into the top ¼ inch of soil.
Was weed preventer put down?
Some weed-and-feed products block new seed. Scotts Triple Action, for one, says not to seed for 4 months after you apply it.
How old is the seed?
Look for a test date within the last 9 months on the bag. Old seed sprouts less.
Is it bluegrass?
Kentucky bluegrass takes 14 to 30 days. People often reseed over it too early.
Our rule and sources
This is our rule of thumb, not a lab model. Every date it gives is an estimate.
The day you seed is day 0.
A warm day is any later day when the soil about 2.4 inches (6 cm) down averages at or above the grass's warm-day temperature in the table.
Sprouts are likely from the day the warm-day count reaches the low end of the grass's published range until it reaches the high end.
After your usual hard freeze, once the soil drops below the line and stays there, counting stops. Seed that has not come up by then is held for spring.
Soil values are model estimates, never sensor readings. Each day is labeled: estimate from recorded weather (Open-Meteo, stored daily), forecast (Open-Meteo, about the next week), or 10-year typical (the average for that date over the last 10 years, Open-Meteo ERA5-Land). Your usual hard freeze is the median first 28°F night for your ZIP area from NOAA's 1991-2020 climate normals. Rain is Open-Meteo's estimate. Germination ranges come from UC IPM, University of Maryland Extension and the other sources below.
The tracker only counts soil temperature. It can't see water, seed depth, seed age or weed preventer.
Sources (11)
[1]University of Maryland Extension, “Starting a New Lawn”. Used for Annual Ryegrass, Perennial Ryegrass, Tall Fescue, Fine Fescue. Checked 2026-10-31.
[2]UC Statewide IPM Program, “Germination times of grasses planted from seed”. Used for Annual Ryegrass, Perennial Ryegrass, Fine Fescue, Kentucky Bluegrass, Buffalograss, Bermudagrass. Checked 2026-10-31.
[3]Barenbrug USA, “The Perfect Temperature for Lawn Seed Germination”. Used for Perennial Ryegrass, Fine Fescue, Bermudagrass. Checked 2026-10-31.
[4]University of Maryland Extension, “Lawn Grasses Grown in Maryland”. Used for Perennial Ryegrass, Tall Fescue, Fine Fescue. Checked 2026-10-31.
[5]Purdue Extension, “Seeding a Turf Area in the Spring (AY-20)”. Used for Kentucky Bluegrass. Checked 2026-10-31.
[6]Dyck Arboretum of the Plains, “Buffalograss: Five Keys to a Successful Planting”. Used for Buffalograss. Checked 2026-10-31.
[7]NC State Extension, “Bermudagrass Production in North Carolina”. Used for Bermudagrass. Checked 2026-10-31.
Seed bags and charts give a range of days. That range assumes the soil is warm enough. The tracker counts only the days that were.
It reads one soil value per day for your area. Past days are estimates from recorded weather. The next week or so is a forecast. Days after that are the 10-year typical for that date.
It only knows soil temperature. It can't see water, seed depth, seed age or weed preventer on your lawn.
Why a seed mix comes up in waves
Most bags mix grasses. Ryegrass comes up first. Bluegrass comes up last. Pick every grass on your label and the tracker gives each one its own dates.
So green fuzz in a week doesn't mean the slow grass failed. Give it until its own window closes.
Most lawn grass seed sprouts in 5 to 30 days. Ryegrass is fastest at 5 to 10 days. Kentucky bluegrass is one of the slowest at 14 to 30 days. Those ranges assume warm enough soil. Days when the soil is too cold don't count, so a cold snap pushes sprouts later.
How long does tall fescue take to germinate?
Tall fescue seed sprouts in 7 to 14 days, per University of Maryland Extension. This tracker counts a day toward that range when soil is 50°F or warmer.
How long does bermuda grass seed take to germinate?
Seeded bermudagrass takes 10 to 30 days, per UC IPM. It needs warm soil, so the tracker only counts days at 65°F or warmer. In fall, bermuda seed often can't bank enough warm days before frost.
Why is my grass seed not germinating?
Check the soil temperature first. The tracker shows every cold day since you seeded. If the window has passed, check that the top inch stays damp, look for a dry crust, make sure seed touches soil instead of thatch, and check whether a weed preventer went down. Old seed also sprouts less.
What soil temperature does grass seed need to germinate?
The tracker counts a day when the soil is at or above the temperature its sources give for good germination: Annual Ryegrass 50°F, Perennial Ryegrass 50°F, Tall Fescue 50°F, Fine Fescue 50°F, Kentucky Bluegrass 55°F, Buffalograss 60°F, Bermudagrass 65°F, Centipede 70°F. For most cool-season grass that is the low end of the best range, not a hard minimum, so some seed can sprout in cooler soil. The sources measure about 1 to 4 inches down. The tracker reads about 2.4 inches (6 cm). Each source is cited on this page.
