When to plant in Summit, IL
USDA Zone 6aEverything below — frost dates, hardiness zone, and what to plant when in Summit, Illinois — is derived from the closest NOAA station with complete climate normals.
Zone 6a means Summit sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
CHICAGO MIDWAY 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 Summit’s own odds, recorded at CHICAGO MIDWAY AP.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 8 | Apr 23 | Apr 9 | Oct 8 | Oct 21 | Nov 1 |
| 32°F | Apr 27 | Apr 11 | Mar 30 | Oct 20 | Oct 31 | Nov 14 |
| 28°F | Apr 14 | Apr 1 | Mar 15 | Oct 31 | Nov 11 | Nov 26 |
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 Summit, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 10 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.
Summit planting FAQ
When is the last spring frost in Summit, IL?
On average, the last spring frost in Summit is around April 11 (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 Summit, IL?
The first fall frost in Summit typically arrives around October 31 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Summit in?
Summit is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Summit?
There are roughly 203 frost-free days in Summit (a moderate growing season), running from the average last frost around April 11 to the first fall frost near October 31.
When should I plant tomatoes in Summit?
In Summit, start tomato seeds indoors around February 14–February 28, then transplant seedlings outdoors around April 18 once the danger of frost has passed.
Never miss a window in Summit
An email when it’s time to start seeds, transplant, and sow — timed to Summit’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Lyons · 3 km
- Justice · 4 km
- Brookfield · 5 km
- Bridgeview · 5 km
- La Grange · 5 km
- Burbank · 6 km
- Berwyn · 6 km
- La Grange Park · 7 km
Frost dates recorded at CHICAGO MIDWAY AP, 5 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 Summit, IL — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00014819. Retrieved from https://blissgarden.com/illinois/summit.