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The 2-inch soil temperature near Portage, MI is currently 54.7°F, a Soil Temps location estimate for these coordinates; the nearest in-ground station (Shabbona 5 NNE) is 170 mi W. That is about 3°F cooler than typical for this date.
Seed now: soil is in the ideal range for cool-season grasses. Tall fescue, Kentucky bluegrass, and perennial ryegrass will germinate reliably in this window.
What you need to check
These windows are computed from Portage's multi-year soil-temperature climatology and NOAA 1991-2020 frost normals, so they reflect this location rather than a regional average. Treat them as a starting plan and confirm with current readings.
The typical first freeze (32°F) near Portage is October 18, from NOAA 1991-2020 frost normals at a weather station 2.9 mi from Portage (a different station from the soil sensor). Cool-season seedlings need about 42 days of root growth before that freeze, so counting back from it puts the last safe seeding day around September 6. Seed later than that and roots will not establish before dormancy; the seed usually survives winter, but germination and coverage suffer.
Cool-season grasses share a seeding band, with tall fescue wanting the warmer end of it; warm-season grasses run higher. Germination floors come from university extension guidance and the band tops are our establishment cutoffs; the dates come from Portage's own station climatology.
| Species | Seeding soil temp | Days to germinate | Right now |
|---|---|---|---|
| Kentucky bluegrass | 60–70°F | 14-30 | Germinates slowly |
| Tall fescue | 60–70°F | 7-12 | Germinates slowly |
| Perennial ryegrass | 60–70°F | 5-10 | Germinates slowly |
| Fine fescue | 60–70°F | 7-14 | Germinates slowly |
| Bermudagrass | 75–90°F | 10-30 | Too cold |
| Zoysia | 75–90°F | varies | Too cold |
| Buffalograss | 75–90°F | 14-30 | Too cold |
| Centipede | 75–90°F | varies | Too cold |
“Right now” compares each species’ band to the current 2-inch modeled estimate of 54.7°F.
Cool-season grasses (tall fescue, Kentucky bluegrass, perennial ryegrass) germinate best when the 2-inch soil temperature stays between 50°F and 65°F. The ideal window is early to mid-spring, or early fall when soil cools back into this range. Fall seeding has less weed competition and more consistent moisture.
Warm-season grasses (Bermuda, zoysia, St. Augustine, centipede) need soil temperatures of65°F or higher for germination. These grasses are best seeded in late spring through early summer when soil has fully warmed.
Use a soil thermometer at 2 inches depth, measured mid-morning after the sun has warmed the surface. Take readings in several spots and average them. One warm day does not mean soil is ready; look for a sustained trend across 3–5 days.
Enter your city or ZIP code for the current 2-inch soil temperature near you, measured at the nearest USDA SCAN, USDA CSCAN, or NOAA USCRN station when one is in range.