Pennsylvania · 24 cities · spring 2026
When to apply crabgrass preventer in Pennsylvania
Last spring's pre-emergent window, largest Pennsylvania 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 Pennsylvania city
Spring 2026 dates and today's verdict.
| City | Held 50°F (2026) | Held 55°F (2026) | Soil today | Today |
|---|---|---|---|---|
| Philadelphia, PA | Mar 30 | May 5 | 57°F | Season over |
| Pittsburgh, PA | Apr 12 | May 17 | 52°F | Season over |
| Allentown, PA | May 6 | May 18 | 50°F | Season over |
| Erie, PA | May 18 | Jun 6 | 46°F | Season over |
| Reading, PA | May 6 | May 18 | 50°F | Season over |
| Scranton, PA | May 17 | May 28 | 46°F | Season over |
| Lancaster, PA | May 5 | May 17 | 50°F | Season over |
| Harrisburg, PA | May 6 | May 18 | 50°F | Season over |
| Altoona, PA | May 17 | May 28 | 47°F | Season over |
| York, PA | Apr 14 | May 17 | 51°F | Season over |
| State College, PA | May 17 | May 28 | 47°F | Season over |
| Wilkes-Barre, PA | May 17 | May 28 | 46°F | Season over |
| Williamsport, PA | May 17 | May 28 | 47°F | Season over |
| Cranberry Township, PA | Apr 13 | May 19 | 48°F | Season over |
| Lebanon, PA | May 6 | May 18 | 50°F | Season over |
| Hazleton, PA | May 17 | May 28 | 46°F | Season over |
| Pottstown, PA | May 6 | May 18 | 50°F | Season over |
| New Castle, PA | May 17 | May 19 | 47°F | Season over |
| Chambersburg, PA | Apr 14 | May 27 | 50°F | Season over |
| Murrysville, PA | Apr 13 | May 19 | 49°F | Season over |
| Johnstown, PA | May 17 | May 28 | 47°F | Season over |
| Carlisle, PA | May 6 | May 27 | 50°F | Season over |
| Lansdale, PA | Apr 13 | May 6 | 54°F | Season over |
| Hanover, PA | Apr 14 | May 18 | 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 Pennsylvania?
- When the soil holds 50 to 55°F. Last spring that was around May 6 to May 19 across 24 Pennsylvania 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 Pennsylvania →
Data: Global Forecast System (GFS) 0.25°, soil temperature 0–10 cm (TSOIL) (NOAA National Centers for Environmental Prediction (NCEP)); GeoNames gazetteer (cities15000) (GeoNames).