Planting calendar / Joliet, IL
Planting calendar for Joliet, IL
Station JOLIET BRANDON RD DAM, IL US (USC00114530) is 2.5 miles away. Median last 32°F 04/19, median first 32°F 10/25. Crop dates below come from University of Illinois Extension. Where the guide uses weeks around a frost date, those weeks are applied to the median 32°F dates because the guide does not name a 10/50/90 level.

Crops in the cited guide
Joliet, IL
Zone 5bAverage annual extreme minimum -15°F to -10°F
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
Illinois. Nearest qualified station: JOLIET BRANDON RD DAM, IL US (USC00114530), 2.5 miles. Median last 32°F April 19. Median first 32°F October 25. The 50% growing-season length is 188 days.
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32°F probabilities at this station
| 10% | 50% | 90% | |
|---|---|---|---|
| Last 32°F on or after | May 7 | April 19 | April 3 |
| First 32°F on or before | October 12 | October 25 | November 6 |
Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.

Planting calendar
Windows below are from University of Illinois Extension, When to Plant, retrieved 2026-10-10. The planting chart is divided into Northern Illinois, Central Illinois, and Southern Illinois. Median dates for the last 32-degree freeze on the same page: Northern Illinois April 8-29; Central Illinois April 8-15; Southern Illinois April 1-8. The page also says southern Illinois can generally start crops two weeks earlier than central Illinois and northern Illinois about two weeks later; the crop rows below are the chart dates, not a recalculation of that sentence.
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State crop pages: Bush beans · Beets · Broccoli · Cabbage · Carrots · Swiss chard · Sweet corn · Cucumber