Wilmington, IL frost dates
Last spring frostApr 16median date
First fall frostOct 26median date
Growing season193 daysfrost-free
Hardiness zone5bZone 5b
How Wilmington compares
- In 8 years out of 10, the last spring frost in Wilmington falls between April 3 and May 3, a 30-day window. The first fall frost falls between October 13 and November 8.
- The median last frost is 1 day earlier than the Illinois median of Apr 17.
- Its 193-day growing season is longer than 70% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 15 days earlier than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 127 nights a year at or below 32°F.
- Compared with Joliet, IL, 24 km away, the last frost here is 3 days earlier than there and the growing season is 4 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 3 |
| 50% (median) | April 16 |
| 10% (safe for tender plants) | May 3 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 13 |
| 50% (median) | October 26 |
| 90% (late) | November 8 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Wilmington, IL
Wilmington, IL frost dates — last frost Apr 16, first frost Oct 26, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Jan 22 to Feb 5Transplant outside: Mar 19 to Apr 2
Start indoors: Feb 5 to Feb 19Transplant outside: Apr 30 to May 14
Start indoors: Feb 5 to Feb 19Transplant outside: Apr 30 to May 14
Start indoors: Feb 19 to Mar 5Transplant outside: Apr 23 to May 7
Start indoors: Feb 19 to Mar 5Transplant outside: Mar 26 to Apr 9Sow outdoors: Mar 19 to Apr 23Plant for fall: Aug 31 to Sep 28
Start indoors: Feb 19 to Mar 5Transplant outside: Mar 19 to Apr 2Sow outdoors: Mar 19 to Apr 2Plant for fall: Aug 17 to Sep 7
Start indoors: Feb 19 to Mar 5Transplant outside: Apr 2 to Apr 16Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 19 to Mar 5Transplant outside: Mar 26 to Apr 9Plant for fall: Jul 20 to Aug 10
Start indoors: Feb 19 to Mar 5Transplant outside: Apr 2 to Apr 16Plant for fall: Jul 20 to Aug 10
Start indoors: Mar 5 to Mar 19Transplant outside: May 7 to May 21Sow outdoors: May 7 to May 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 23 to May 7
Sow outdoors: Mar 5 to Mar 26Plant for fall: Aug 3 to Aug 24
Sow outdoors: Mar 5 to Mar 26Plant for fall: Aug 31 to Sep 21
Sow outdoors: Mar 12 to Apr 23Plant for fall: Sep 14 to Oct 5
Start indoors: Mar 19 to Mar 26Transplant outside: Apr 30 to May 7Sow outdoors: Apr 23 to May 7Plant for fall: Aug 10 to Aug 24
Start indoors: Mar 19 to Mar 26Sow outdoors: Apr 23 to May 7Plant for fall: Aug 17 to Aug 31
Start indoors: Mar 19 to Mar 26Sow outdoors: Apr 23 to May 7
Start indoors: Mar 19 to Mar 26Transplant outside: Apr 30 to May 14
Sow outdoors: Mar 26 to Apr 23Plant for fall: Aug 3 to Aug 17
Sow outdoors: Mar 26 to Apr 23Plant for fall: Aug 17 to Aug 31
Sow outdoors: Mar 26 to Apr 16
Sow outdoors: Apr 2 to Apr 30Plant for fall: Aug 17 to Aug 31
Sow outdoors: Apr 2 to Apr 23Plant for fall: Aug 31 to Sep 21
Sow outdoors: Apr 23 to May 14Plant for fall: Aug 10 to Aug 24
Sow outdoors: Apr 23 to May 7
Transplant outside: Apr 30 to May 21
Plant for fall: Oct 12 to Nov 16
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Wilmington, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 22 – Feb 5 | Mar 19 – Apr 2 | — | — |
| Peppers | Feb 5 – Feb 19 | Apr 30 – May 14 | — | — |
| Eggplant | Feb 5 – Feb 19 | Apr 30 – May 14 | — | — |
| Tomatoes | Feb 19 – Mar 5 | Apr 23 – May 7 | — | — |
| Lettuce | Feb 19 – Mar 5 | Mar 26 – Apr 9 | Mar 19 – Apr 23 | Aug 31 – Sep 28 |
| Kale | Feb 19 – Mar 5 | Mar 19 – Apr 2 | Mar 19 – Apr 2 | Aug 17 – Sep 7 |
| Broccoli | Feb 19 – Mar 5 | Apr 2 – Apr 16 | — | Jul 20 – Aug 10 |
| Cabbage | Feb 19 – Mar 5 | Mar 26 – Apr 9 | — | Jul 20 – Aug 10 |
| Cauliflower | Feb 19 – Mar 5 | Apr 2 – Apr 16 | — | Jul 20 – Aug 10 |
| Okra | Mar 5 – Mar 19 | May 7 – May 21 | May 7 – May 21 | — |
| Basil | Mar 5 – Mar 19 | Apr 23 – May 7 | — | — |
| Peas | — | — | Mar 5 – Mar 26 | Aug 3 – Aug 24 |
| Spinach | — | — | Mar 5 – Mar 26 | Aug 31 – Sep 21 |
| Radishes | — | — | Mar 12 – Apr 23 | Sep 14 – Oct 5 |
| Cucumbers | Mar 19 – Mar 26 | Apr 30 – May 7 | Apr 23 – May 7 | Aug 10 – Aug 24 |
| Zucchini & Summer Squash | Mar 19 – Mar 26 | — | Apr 23 – May 7 | Aug 17 – Aug 31 |
| Winter Squash & Pumpkins | Mar 19 – Mar 26 | — | Apr 23 – May 7 | — |
| Melons & Watermelon | Mar 19 – Mar 26 | Apr 30 – May 14 | — | — |
| Carrots | — | — | Mar 26 – Apr 23 | Aug 3 – Aug 17 |
| Beets | — | — | Mar 26 – Apr 23 | Aug 17 – Aug 31 |
| Potatoes | — | — | Mar 26 – Apr 16 | — |
| Swiss Chard | — | — | Apr 2 – Apr 30 | Aug 17 – Aug 31 |
| Cilantro | — | — | Apr 2 – Apr 23 | Aug 31 – Sep 21 |
| Green Beans | — | — | Apr 23 – May 14 | Aug 10 – Aug 24 |
| Sweet Corn | — | — | Apr 23 – May 7 | — |
| Sweet Potatoes | — | Apr 30 – May 21 | — | — |
| Garlic | — | — | — | Oct 12 – Nov 16 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Channahon Dresden Isl Dam, IL weather station, 15 km away (elevation 505 ft (154 m)).
Frost dates near Wilmington
- Braidwood Apr 16 · Oct 26
- Coal City Apr 16 · Oct 26
- Braceville Apr 27 · Oct 15
- Elwood Apr 19 · Oct 25
- Channahon Apr 16 · Oct 26
- Essex Apr 27 · Oct 15
- Bonfield Apr 19 · Oct 24
- South Wilmington Apr 27 · Oct 15
- Manhattan Apr 19 · Oct 25
- Minooka Apr 16 · Oct 26
Frequently asked questions
When is the last frost in Wilmington, IL?
The median last spring frost in Wilmington, IL is April 16. There is still about a 10% chance of frost after May 3, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Wilmington, IL?
The median first fall frost is October 26, with about a 10% chance of frost before October 13.
How long is the growing season in Wilmington, IL?
About 193 days between the median last spring frost and first fall frost.
What planting zone is Wilmington, IL?
Wilmington, IL is in USDA hardiness zone 5b.