Putnam, IL frost dates
Last spring frostApr 18median date
First fall frostOct 22median date
Growing season187 daysfrost-free
Hardiness zone5bZone 5b
How Putnam compares
- In 8 years out of 10, the last spring frost in Putnam falls between April 3 and May 3, a 30-day window. The first fall frost falls between October 7 and November 3.
- The median last frost is 1 day later than the Illinois median of Apr 17.
- Its 187-day growing season is longer than 48% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 13 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 119 nights a year at or below 32°F.
- Compared with Peoria, IL, 55 km away, the last frost here is 2 days later than there and the growing season is 3 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 3 |
| 50% (median) | April 18 |
| 10% (safe for tender plants) | May 3 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 7 |
| 50% (median) | October 22 |
| 90% (late) | November 3 |
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 Putnam, IL
Putnam, IL frost dates — last frost Apr 18, first frost Oct 22, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Jan 24 to Feb 7Transplant outside: Mar 21 to Apr 4
Start indoors: Feb 7 to Feb 21Transplant outside: May 2 to May 16
Start indoors: Feb 7 to Feb 21Transplant outside: May 2 to May 16
Start indoors: Feb 21 to Mar 7Transplant outside: Apr 25 to May 9
Start indoors: Feb 21 to Mar 7Transplant outside: Mar 28 to Apr 11Sow outdoors: Mar 21 to Apr 25Plant for fall: Aug 27 to Sep 24
Start indoors: Feb 21 to Mar 7Transplant outside: Mar 21 to Apr 4Sow outdoors: Mar 21 to Apr 4Plant for fall: Aug 13 to Sep 3
Start indoors: Feb 21 to Mar 7Transplant outside: Apr 4 to Apr 18Plant for fall: Jul 16 to Aug 6
Start indoors: Feb 21 to Mar 7Transplant outside: Mar 28 to Apr 11Plant for fall: Jul 16 to Aug 6
Start indoors: Feb 21 to Mar 7Transplant outside: Apr 4 to Apr 18Plant for fall: Jul 16 to Aug 6
Start indoors: Mar 7 to Mar 21Transplant outside: May 9 to May 23Sow outdoors: May 9 to May 23
Start indoors: Mar 7 to Mar 21Transplant outside: Apr 25 to May 9
Sow outdoors: Mar 7 to Mar 28Plant for fall: Jul 30 to Aug 20
Sow outdoors: Mar 7 to Mar 28Plant for fall: Aug 27 to Sep 17
Sow outdoors: Mar 14 to Apr 25Plant for fall: Sep 10 to Oct 1
Start indoors: Mar 21 to Mar 28Transplant outside: May 2 to May 9Sow outdoors: Apr 25 to May 9Plant for fall: Aug 6 to Aug 20
Start indoors: Mar 21 to Mar 28Sow outdoors: Apr 25 to May 9Plant for fall: Aug 13 to Aug 27
Start indoors: Mar 21 to Mar 28Sow outdoors: Apr 25 to May 9
Start indoors: Mar 21 to Mar 28Transplant outside: May 2 to May 16
Sow outdoors: Mar 28 to Apr 25Plant for fall: Jul 30 to Aug 13
Sow outdoors: Mar 28 to Apr 25Plant for fall: Aug 13 to Aug 27
Sow outdoors: Mar 28 to Apr 18
Sow outdoors: Apr 4 to May 2Plant for fall: Aug 13 to Aug 27
Sow outdoors: Apr 4 to Apr 25Plant for fall: Aug 27 to Sep 17
Sow outdoors: Apr 25 to May 16Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 25 to May 9
Transplant outside: May 2 to May 23
Plant for fall: Oct 8 to Nov 12
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Putnam, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 24 – Feb 7 | Mar 21 – Apr 4 | — | — |
| Peppers | Feb 7 – Feb 21 | May 2 – May 16 | — | — |
| Eggplant | Feb 7 – Feb 21 | May 2 – May 16 | — | — |
| Tomatoes | Feb 21 – Mar 7 | Apr 25 – May 9 | — | — |
| Lettuce | Feb 21 – Mar 7 | Mar 28 – Apr 11 | Mar 21 – Apr 25 | Aug 27 – Sep 24 |
| Kale | Feb 21 – Mar 7 | Mar 21 – Apr 4 | Mar 21 – Apr 4 | Aug 13 – Sep 3 |
| Broccoli | Feb 21 – Mar 7 | Apr 4 – Apr 18 | — | Jul 16 – Aug 6 |
| Cabbage | Feb 21 – Mar 7 | Mar 28 – Apr 11 | — | Jul 16 – Aug 6 |
| Cauliflower | Feb 21 – Mar 7 | Apr 4 – Apr 18 | — | Jul 16 – Aug 6 |
| Okra | Mar 7 – Mar 21 | May 9 – May 23 | May 9 – May 23 | — |
| Basil | Mar 7 – Mar 21 | Apr 25 – May 9 | — | — |
| Peas | — | — | Mar 7 – Mar 28 | Jul 30 – Aug 20 |
| Spinach | — | — | Mar 7 – Mar 28 | Aug 27 – Sep 17 |
| Radishes | — | — | Mar 14 – Apr 25 | Sep 10 – Oct 1 |
| Cucumbers | Mar 21 – Mar 28 | May 2 – May 9 | Apr 25 – May 9 | Aug 6 – Aug 20 |
| Zucchini & Summer Squash | Mar 21 – Mar 28 | — | Apr 25 – May 9 | Aug 13 – Aug 27 |
| Winter Squash & Pumpkins | Mar 21 – Mar 28 | — | Apr 25 – May 9 | — |
| Melons & Watermelon | Mar 21 – Mar 28 | May 2 – May 16 | — | — |
| Carrots | — | — | Mar 28 – Apr 25 | Jul 30 – Aug 13 |
| Beets | — | — | Mar 28 – Apr 25 | Aug 13 – Aug 27 |
| Potatoes | — | — | Mar 28 – Apr 18 | — |
| Swiss Chard | — | — | Apr 4 – May 2 | Aug 13 – Aug 27 |
| Cilantro | — | — | Apr 4 – Apr 25 | Aug 27 – Sep 17 |
| Green Beans | — | — | Apr 25 – May 16 | Aug 6 – Aug 20 |
| Sweet Corn | — | — | Apr 25 – May 9 | — |
| Sweet Potatoes | — | May 2 – May 23 | — | — |
| Garlic | — | — | — | Oct 8 – Nov 12 |
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 Hennepin, IL weather station, 11 km away (elevation 515 ft (157 m)).
Frost dates near Putnam
- Henry Apr 20 · Oct 17
- Hennepin Apr 18 · Oct 22
- Tiskilwa Apr 22 · Oct 17
- Bureau Apr 24 · Oct 17
- Depue Apr 24 · Oct 17
- Mark Apr 24 · Oct 17
- Bradford Apr 24 · Oct 17
- Princeton Apr 22 · Oct 17
- Mc Nabb Apr 18 · Oct 22
- Lacon Apr 20 · Oct 17
Frequently asked questions
When is the last frost in Putnam, IL?
The median last spring frost in Putnam, IL is April 18. 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 Putnam, IL?
The median first fall frost is October 22, with about a 10% chance of frost before October 7.
How long is the growing season in Putnam, IL?
About 187 days between the median last spring frost and first fall frost.
What planting zone is Putnam, IL?
Putnam, IL is in USDA hardiness zone 5b.