Bloomington, Illinois: planting zone & frost dates
Bloomington 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 May 1 and the first fall frost around Oct 11.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 11 | Oct 2 |
| Typical planning date (30% risk) | May 1 | Oct 11 |
| Median (50%) | Apr 25 | Oct 16 |
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 NORMAL 4NE, IL (USC00116200), 5.2 mi (8.3 km) from the city center and 52 ft lower than the city center (-16 m). Record used for the 1991–2020 normals: 26 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Bloomington
All 3 ZIP codes covering Bloomington are in zone 6a.
Vegetable planting calendar for Bloomington
Dates are counted from the 30%-risk frost dates above (last frost May 1, first frost Oct 11). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 6 – Mar 20 | May 8 – May 22 | — | — |
| Pepper | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Lettuce | Mar 20 – Apr 3 | Apr 17 – May 8 | Apr 3 – May 15 | Aug 2 – Aug 30 |
| Green Beans | — | — | May 8 – Jun 12 | Jul 19 – Aug 2 |
| Sweet Corn | — | — | May 8 – Jun 5 | — |
| Zucchini & Summer Squash | Apr 3 – Apr 10 | May 8 – May 22 | May 8 – May 29 | Jul 19 – Aug 2 |
| Cucumber | Apr 3 – Apr 10 | May 15 – May 22 | May 8 – May 29 | Jul 19 – Aug 2 |
| Carrot | — | — | Apr 10 – May 15 | Jul 19 – Aug 2 |
| Onion | Feb 6 – Feb 20 | Apr 3 – Apr 17 | — | — |
| Potato | — | Apr 3 – Apr 24 | — | — |
| Basil | Mar 20 – Apr 3 | May 15 – May 29 | May 15 – Jun 5 | — |
| Spinach | — | — | Mar 20 – Apr 17 | Aug 16 – Sep 13 |
| Kale | Mar 6 – Mar 20 | Apr 3 – Apr 24 | Apr 3 – Apr 24 | Aug 2 – Aug 30 |
| Broccoli | Mar 6 – Mar 20 | Apr 17 – May 8 | — | Jul 19 – Aug 2 |
| Peas | — | — | Mar 20 – Apr 10 | Aug 2 – Aug 16 |
| Eggplant | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Cabbage | Mar 6 – Mar 20 | Apr 3 – Apr 17 | — | Jul 19 – Aug 2 |
| Radish | — | — | Mar 27 – May 15 | Aug 30 – Sep 27 |
| Strawberry | — | Apr 3 – Apr 24 | — | — |
| Beets | — | — | Apr 10 – May 22 | Aug 2 – Aug 16 |
Nearby cities in Illinois
- Peoria — zone 6a, last frost Apr 23, first frost Oct 18
- Champaign — zone 6a, last frost Apr 21, first frost Oct 19
- Springfield — zone 6a, last frost Apr 20, first frost Oct 17
- Joliet — zone 6a, last frost Apr 26, first frost Oct 20
- Aurora — zone 5b, last frost Apr 25, first frost Oct 18
- Naperville — zone 5b, last frost May 4, first frost Oct 11
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
Bloomington gardening questions
When is the last frost in Bloomington, IL?
Plan around May 1. At NOAA's Normal 4NE, IL station, 5.2 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 25, and after May 11 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 14. The 90% and 10% dates are 30 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Bloomington, IL?
Start seeds indoors Mar 6 – Mar 20 and set transplants outside May 8 – May 22, once nights stay above 50°F and the soil is near 60°F. That leaves 163 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 Bloomington?
About 172 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 152 days, and in 1 year in 10 it runs 192 days or more. In fall there is a 10% chance of frost by Oct 2 and a 30% chance by Oct 11. That ranks 11th longest of 14 Illinois cities on this site.
When should I plant a fall garden in Bloomington?
Count back from the first fall frost (Oct 11): transplant broccoli Jul 19 – Aug 2; sow kale Aug 2 – Aug 30; sow lettuce Aug 2 – Aug 30; sow radishes Aug 30 – Sep 27. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 27. How the math works: succession and fall planting.
Did Bloomington's hardiness zone change on the 2023 map?
Yes. Most of Bloomington 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 Bloomington compare with Peoria, IL?
Both are in zone 6a. The typical last spring frost in Bloomington (May 1) comes about 8 days later than in Peoria, IL (Apr 23), 39 miles away, and the first fall frost is Oct 11 versus Oct 18. The two cities use different NOAA stations.