When to plant in Columbia, IL
USDA Zone 7aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Columbia, Illinois — all computed from Columbia's nearest NOAA weather station.
In zone 7a, Columbia supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
Frost probability
CAHOKIA · 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 Columbia’s own odds, recorded at CAHOKIA.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 3 | Apr 18 | Apr 4 | Oct 5 | Oct 18 | Oct 28 |
| 32°F | Apr 20 | Apr 6 | Mar 22 | Oct 14 | Oct 27 | Nov 7 |
| 28°F | Apr 10 | Mar 27 | Mar 11 | Oct 25 | Nov 5 | Nov 23 |
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 Columbia, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 20 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.
Columbia planting FAQ
When is the last spring frost in Columbia, IL?
On average, the last spring frost in Columbia is around April 6 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Columbia, IL?
The first fall frost in Columbia typically arrives around October 27 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Columbia in?
Columbia 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 Columbia?
Columbia has about 204 frost-free days — a moderate growing season — between the average last spring frost (April 6) and first fall frost (October 27).
When should I plant tomatoes in Columbia?
For Columbia, sow tomatoes indoors about February 9–February 23 and move the seedlings out around April 13, after the last spring frost.
Never miss a window in Columbia
An email when it’s time to start seeds, transplant, and sow — timed to Columbia’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at CAHOKIA, 12 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 Columbia, IL — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00111160. Retrieved from https://blissgarden.com/illinois/columbia.