Illinois · 29 cities · spring 2026
When to apply crabgrass preventer in Illinois
Last spring's pre-emergent window, largest Illinois cities
Each bar runs from the day the soil held 50°F to the day it held 55°F (2026).
- 50°F to 55°F
Every Illinois city
Spring 2026 dates and today's verdict.
| City | Held 50°F (2026) | Held 55°F (2026) | Soil today | Today |
|---|---|---|---|---|
| Chicago, IL | Apr 10 | Apr 13 | 54°F | Season over |
| Aurora, IL | Apr 12 | May 17 | 48°F | Season over |
| Rockford, IL | Apr 13 | May 16 | 48°F | Season over |
| Joliet, IL | Apr 12 | May 16 | 50°F | Season over |
| Peoria, IL | Apr 10 | May 12 | 52°F | Season over |
| Springfield, IL | Mar 22 | Apr 12 | 56°F | Season over |
| Elgin, IL | Apr 13 | May 17 | 48°F | Season over |
| Champaign, IL | Mar 22 | Apr 12 | 55°F | Season over |
| Bloomington, IL | Apr 10 | Apr 12 | 53°F | Season over |
| Arlington Heights, IL | Apr 12 | May 12 | 52°F | Season over |
| Decatur, IL | Mar 22 | Apr 12 | 56°F | Season over |
| Downers Grove, IL | Apr 11 | May 11 | 52°F | Season over |
| DeKalb, IL | Apr 12 | May 16 | 48°F | Season over |
| Quincy, IL | Mar 22 | Apr 12 | 55°F | Season over |
| Danville, IL | Mar 29 | Apr 12 | 55°F | Season over |
| Galesburg, IL | Apr 10 | May 12 | 51°F | Season over |
| North Chicago, IL | Apr 12 | May 16 | 53°F | Season over |
| Upper Alton, IL | Mar 22 | Apr 11 | 58°F | Season over |
| O'Fallon, IL | Mar 22 | Apr 11 | 58°F | Season over |
| Kankakee, IL | Apr 10 | May 11 | 53°F | Season over |
| McHenry, IL | May 12 | May 17 | 48°F | Season over |
| Carbondale, IL | Mar 5 | Mar 22 | 58°F | Season over |
| Freeport, IL | Apr 13 | May 16 | 48°F | Season over |
| Charleston, IL | Mar 22 | Apr 12 | 57°F | Season over |
| Jacksonville, IL | Mar 22 | Apr 12 | 56°F | Season over |
| Macomb, IL | Mar 22 | May 12 | 54°F | Season over |
| Ottawa, IL | Apr 11 | May 12 | 50°F | Season over |
| Dixon, IL | Apr 12 | May 13 | 49°F | Season over |
| Mount Vernon, IL | Mar 6 | Apr 11 | 58°F | Season over |
Crabgrass seeds start to germinate once the top 2 to 4 inches of soil stay near 55°F for several days. A pre-emergent works as a barrier in the soil, so it has to be down and watered in before that: the usual advice is to apply it while the soil holds 50 to 55°F. The dates here are when the modelled soil began to hold each temperature last spring; this year's window will move with the weather, which is why each city page shows today's reading and the 7-day forecast.
Questions
- When should I put down crabgrass preventer in Illinois?
- When the soil holds 50 to 55°F. Last spring that was around Apr 10 to May 11 across 29 Illinois cities, earlier in the south and in cities.
- Is it too late to apply pre-emergent?
- Once the soil has held 55°F for a week or more, crabgrass is germinating and a pre-emergent will not stop the seedlings already up. Each city page says which side of that line it is on today.
Soil temperature today in Illinois →
Data: Global Forecast System (GFS) 0.25°, soil temperature 0–10 cm (TSOIL) (NOAA National Centers for Environmental Prediction (NCEP)); GeoNames gazetteer (cities15000) (GeoNames).