When to plant watermelon in Illinois
Illinois spans USDA zones 5a–7a, so the right time to plant watermelon shifts by weeks across the state. The window to transplant seedlings outdoors runs from about April 11 in Granite City to May 8 in McHenry — below are local dates for 226 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Transplant out |
|---|---|---|---|---|
| Chicago | 6a | April 10 | November 5 | April 17 – April 24 |
| Aurora | 5b | April 19 | October 23 | April 26 – May 3 |
| Naperville | 5b | April 28 | October 16 | May 5 – May 12 |
| Joliet | 5b | April 19 | October 25 | April 26 – May 3 |
| Rockford | 5b | April 24 | October 17 | May 1 – May 8 |
| Elgin | 5b | April 26 | October 18 | May 3 – May 10 |
| Springfield | 6a | April 15 | October 22 | April 22 – April 29 |
| Peoria | 6a | April 16 | October 23 | April 23 – April 30 |
Watermelon in Illinois: FAQ
When can I plant watermelon in Illinois?
Across Illinois, the time to transplant watermelon spans roughly April 11 in Granite City to May 8 in McHenry, each following that city's local frost dates.
Does the watermelon planting date vary across Illinois?
Yes. Illinois publishes 226 cities with their own frost dates, so the right watermelon planting window shifts by weeks between the warmest and coldest parts of the state — use your city's page for the exact dates.
How long does watermelon take to grow in Illinois?
Watermelon takes about 75–95 days to reach harvest once planted — check that this fits inside your city's frost-free season on its place page.
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