Champaign, Illinois: planting zone & frost dates
Champaign is in USDA plant hardiness zone 6a, where the average coldest winter night reaches -10 to -5°F (-23.3 to -20.6°C). The typical last spring frost is around Apr 21 and the first fall frost around Oct 19.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Apr 29 | Oct 11 |
| Typical planning date (30% risk) | Apr 21 | Oct 19 |
| Median (50%) | Apr 15 | Oct 24 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station CHAMPAIGN 3S, IL (USC00118740), 2.7 mi (4.4 km) from the city center and 52 ft lower than the city center (-16 m). Record used for the 1991–2020 normals: 29 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Champaign
All 3 ZIP codes covering Champaign are in zone 6a.
Vegetable planting calendar for Champaign
Dates are counted from the 30%-risk frost dates above (last frost Apr 21, first frost Oct 19). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Feb 24 – Mar 10 | Apr 28 – May 12 | — | — |
| Pepper | Feb 10 – Feb 24 | May 5 – May 19 | — | — |
| Lettuce | Mar 10 – Mar 24 | Apr 7 – Apr 28 | Mar 24 – May 5 | Aug 10 – Sep 7 |
| Green Beans | — | — | Apr 28 – Jun 2 | Jul 27 – Aug 10 |
| Sweet Corn | — | — | Apr 28 – May 26 | — |
| Zucchini & Summer Squash | Mar 24 – Mar 31 | Apr 28 – May 12 | Apr 28 – May 19 | Jul 27 – Aug 10 |
| Cucumber | Mar 24 – Mar 31 | May 5 – May 12 | Apr 28 – May 19 | Jul 27 – Aug 10 |
| Carrot | — | — | Mar 31 – May 5 | Jul 27 – Aug 10 |
| Onion | Jan 27 – Feb 10 | Mar 24 – Apr 7 | — | — |
| Potato | — | Mar 24 – Apr 14 | — | — |
| Basil | Mar 10 – Mar 24 | May 5 – May 19 | May 5 – May 26 | — |
| Spinach | — | — | Mar 10 – Apr 7 | Aug 24 – Sep 21 |
| Kale | Feb 24 – Mar 10 | Mar 24 – Apr 14 | Mar 24 – Apr 14 | Aug 10 – Sep 7 |
| Broccoli | Feb 24 – Mar 10 | Apr 7 – Apr 28 | — | Jul 27 – Aug 10 |
| Peas | — | — | Mar 10 – Mar 31 | Aug 10 – Aug 24 |
| Eggplant | Feb 10 – Feb 24 | May 5 – May 19 | — | — |
| Cabbage | Feb 24 – Mar 10 | Mar 24 – Apr 7 | — | Jul 27 – Aug 10 |
| Radish | — | — | Mar 17 – May 5 | Sep 7 – Oct 5 |
| Strawberry | — | Mar 24 – Apr 14 | — | — |
| Beets | — | — | Mar 31 – May 12 | Aug 10 – Aug 24 |
Nearby cities in Illinois
- Bloomington — zone 6a, last frost May 1, first frost Oct 11
- Springfield — zone 6a, last frost Apr 20, first frost Oct 17
- Joliet — zone 6a, last frost Apr 26, first frost Oct 20
- Peoria — zone 6a, last frost Apr 23, first frost Oct 18
- Naperville — zone 5b, last frost May 4, first frost Oct 11
- Aurora — zone 5b, last frost Apr 25, first frost Oct 18
More: all Illinois cities · other zone 6a cities: Chicago, IL, Denver, CO, Milwaukee, WI, Colorado Springs, CO, Omaha, NE, Aurora, CO, Lincoln, NE, Fort Wayne, IN
Champaign gardening questions
When is the last frost in Champaign, IL?
Plan around Apr 21. At NOAA's Champaign 3S, IL station, 2.7 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 15, and after Apr 29 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 4. The last frost is fairly predictable here: only 28 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Champaign, IL?
Start seeds indoors Feb 24 – Mar 10 and set transplants outside Apr 28 – May 12, once nights stay above 50°F and the soil is near 60°F. That leaves 181 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Champaign?
About 190 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 171 days, and in 1 year in 10 it runs 209 days or more. In fall there is a 10% chance of frost by Oct 11 and a 30% chance by Oct 19. That ranks 3rd longest of 14 Illinois cities on this site.
When should I plant a fall garden in Champaign?
Count back from the first fall frost (Oct 19): transplant broccoli Jul 27 – Aug 10; sow kale Aug 10 – Sep 7; sow lettuce Aug 10 – Sep 7; sow radishes Sep 7 – Oct 5. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 2. How the math works: succession and fall planting.
Did Champaign's hardiness zone change on the 2023 map?
Yes. Most of Champaign was zone 5b on the 2012 map and is zone 6a on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Champaign compare with Bloomington, IL?
Both are in zone 6a. The typical last spring frost in Champaign (Apr 21) comes about 10 days earlier than in Bloomington, IL (May 1), 44 miles away, and the first fall frost is Oct 19 versus Oct 11. The two cities use different NOAA stations.