Soil temperature for lawn care: the numbers that time each job
Updated October 18, 2026. Live numbers refresh hourly.
Soil temperature, measured in the top few inches, is the most reliable lawn-care clock: put down crabgrass pre-emergent when soil holds 50–55°F, seed cool-season grass while soil is near 60°F or warmer, and make the last fertilizer round before soil drops below about 40°F. Today the 0–4 inch soil around Denver, CO averages 61°F and is warming.
- Soil today
- 61°F
- +4.1°F over 7 days
Live data for Denver, CO. Check your own ZIP below for local numbers.
Why soil, not air or the calendar
Seeds and roots live in the soil, and soil changes temperature more slowly than air. One warm afternoon doesn't wake crabgrass seed; several days of warm soil does. That's why extension researchers express timing in soil temperature or in growing degree days, which add up daily warmth over time. Dates on a bag are a regional average and can miss by weeks in either direction.
We show the daily mean temperature of the top 0–10 cm (about 0–4 inches) of soil on every city and ZIP page, with the past seven days and a 10-day forecast. In spring we add a countdown to 55°F, the point at which crabgrass starts germinating.
| Soil temperature | What it means | Source |
|---|---|---|
| Below 40°F | Grass growth slows sharply; skip fertilizer on frozen ground | Purdue |
| Low 40s (fall) | Dormant seeding window | UMass |
| 50–55°F (spring) | Apply crabgrass pre-emergent | MSU |
| 55°F for 4–5 days | Crabgrass germination begins | MSU |
| 50–65°F | Best root growth for cool-season grass | Penn State |
| 59–86°F | Kentucky bluegrass germination optimum | Penn State |
| 60–70°F | About 80% of crabgrass germination | MSU |
Spring: pre-emergent and the 55°F mark
Michigan State University recommends applying crabgrass pre-emergent when soil in the top 2 inches is consistently 50–55°F. Their crabgrass biology notes germination starts after about four to five consecutive days at 55°F, and MSU says about 80% of germination happens once soil reaches 60–70°F. Purdue Extension describes germination at around 60°F for three to five days at a quarter-inch depth and suggests applying one to two weeks ahead.
MSU also uses growing degree days: the window is 250–500 GDD (base 32°F) counted from February 15. We start tracking GDD on February 15, 2027. Regional timing guides: Denver, Michigan, Minnesota, Indiana and Ohio, Pennsylvania and New England.
Fall: seeding, roots and the last feeding
Penn State calls late summer the best time to seed cool-season grass; warm soil speeds germination, and roots grow best at 50–65°F. Once soil drops into the 50s, germination slows. UMass describes dormant seeding once air stays below 50°F and soil is in the low 40s, so seed waits for spring. Purdue notes growth slows once soil falls below about 40°F and fertilizer shouldn't go on frozen soil, which sets a practical end to the late-fall feeding.
What soil temperature doesn't tell you
Grub control is timed by the insect's life cycle, not a soil-temperature threshold; see grub control timing. Fall broadleaf weed control depends on air temperature and active weed growth; see fall broadleaf control. And our soil data is modeled on a grid about 17 miles across from NOAA's GFS model, so a sunny strip by the driveway can run warmer than the number shown.
Questions
What soil temperature should I apply pre-emergent?
When soil in the top 2 inches is consistently 50–55°F, per Michigan State University, and before it holds 55°F for four to five days.
What soil temperature is best for grass seed?
For cool-season grasses, warm late-summer soil is best. Penn State lists Kentucky bluegrass germination as optimal at 59–86°F.
At what soil temperature does grass stop growing?
Purdue notes cool-season turf growth slows greatly once soil drops below about 40°F.
Where does your soil temperature come from?
NOAA's GFS weather model, 0–10 cm soil layer, about 0.25° (roughly 17 miles) resolution, updated four times a day. It's public domain government data.
Sources
- Michigan State University Extension: Timing crabgrass pre-emergence applications
- Michigan State University: Crabgrass weed biology
- Purdue Extension: Do you get crabby about crabgrass?
- Penn State Extension: The Cool-Season Turfgrasses, Basic Structures, Growth and Development
- Penn State Extension: Lawn Establishment
- UMass Extension: Late-season establishment considerations
- Purdue University: Fall fertilization for home lawns
Soil temperatures: NOAA GFS model, 0–10 cm layer. Snow: NOAA and National Weather Service. See how we measure.