Iowa · 17 cities · spring 2026
When to apply crabgrass preventer in Iowa
Last spring's pre-emergent window, largest Iowa 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 Iowa city
Spring 2026 dates and today's verdict.
| City | Held 50°F (2026) | Held 55°F (2026) | Soil today | Today |
|---|---|---|---|---|
| Des Moines, IA | Apr 12 | May 12 | 52°F | Season over |
| Cedar Rapids, IA | Apr 12 | May 13 | 50°F | Season over |
| Davenport, IA | Apr 10 | May 12 | 50°F | Season over |
| Sioux City, IA | Mar 22 | Apr 14 | 51°F | Season over |
| Iowa City, IA | Apr 12 | May 13 | 50°F | Season over |
| Waterloo, IA | Apr 13 | May 12 | 50°F | Season over |
| Ames, IA | Apr 12 | May 11 | 51°F | Season over |
| Dubuque, IA | May 13 | May 25 | 48°F | Season over |
| Marshalltown, IA | Apr 13 | May 12 | 50°F | Season over |
| Mason City, IA | Apr 13 | May 12 | 50°F | Season over |
| Clinton, IA | Apr 12 | May 12 | 49°F | Season over |
| Burlington, IA | Mar 22 | May 12 | 53°F | Season over |
| Fort Dodge, IA | Apr 12 | May 5 | 51°F | Season over |
| Ottumwa, IA | Mar 22 | May 12 | 53°F | Season over |
| Muscatine, IA | Apr 12 | May 12 | 50°F | Season over |
| Indianola, IA | Apr 12 | May 12 | 52°F | Season over |
| Newton, IA | Apr 12 | May 12 | 50°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 Iowa?
- When the soil holds 50 to 55°F. Last spring that was around Apr 12 to May 12 across 17 Iowa 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 Iowa →
Data: Global Forecast System (GFS) 0.25°, soil temperature 0–10 cm (TSOIL) (NOAA National Centers for Environmental Prediction (NCEP)); GeoNames gazetteer (cities15000) (GeoNames).