When to plant in Collinsville, IL
USDA Zone 7aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Collinsville, Illinois — all computed from Collinsville's nearest NOAA weather station.
These dates come from a station roughly 18 km away, the closest with full normals; terrain around Collinsville (elevation, water, pavement) can move your real frost dates a few days either way. Zone 7a means many perennials and even some tender shrubs overwinter in Collinsville, while your frost dates still decide when annuals go out.
Frost probability
CAHOKIA ST LOUIS AP · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Collinsville’s own odds, recorded at CAHOKIA ST LOUIS AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 4 | Apr 19 | Apr 4 | Oct 3 | Oct 17 | Oct 28 |
| 32°F | Apr 23 | Apr 8 | Mar 23 | Oct 12 | Oct 26 | Nov 7 |
| 28°F | Apr 12 | Mar 28 | Mar 10 | Oct 24 | Nov 6 | Nov 24 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Collinsville, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 22 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Collinsville planting FAQ
When is the last spring frost in Collinsville, IL?
Plan for the last spring frost in Collinsville around April 8 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Collinsville, IL?
In Collinsville, the first 32°F freeze of fall lands around October 26 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Collinsville in?
Collinsville is in USDA hardiness zone 7a. In zone 7a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Collinsville?
There are roughly 201 frost-free days in Collinsville (a moderate growing season), running from the average last frost around April 8 to the first fall frost near October 26.
When should I plant tomatoes in Collinsville?
In Collinsville, start tomato seeds indoors around February 11–February 25, then transplant seedlings outdoors around April 15 once the danger of frost has passed.
Never miss a window in Collinsville
An email when it’s time to start seeds, transplant, and sow — timed to Collinsville’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Fairview Heights · 9 km
- Glen Carbon · 9 km
- Troy · 11 km
- Granite City · 12 km
- O'Fallon · 12 km
- East St. Louis · 13 km
- Edwardsville · 13 km
- Swansea · 14 km
Frost dates recorded at CAHOKIA ST LOUIS AP, 18 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Collinsville, IL — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00003960. Retrieved from https://blissgarden.com/illinois/collinsville.