Posen, IL frost dates
Last spring frostApr 10median date
First fall frostNov 1median date
Growing season205 daysfrost-free
Hardiness zone6aZone 6a
How Posen compares
- In 8 years out of 10, the last spring frost in Posen falls between March 30 and April 26, a 27-day window. The first fall frost falls between October 21 and November 16.
- The median last frost is 7 days earlier than the Illinois median of Apr 17.
- Its 205-day growing season is longer than 90% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 19 days earlier than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 108 nights a year at or below 32°F.
- Compared with Tinley Park, IL, 13 km away, the last frost here is 13 days earlier than there and the growing season is 25 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 30 |
| 50% (median) | April 10 |
| 10% (safe for tender plants) | April 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 21 |
| 50% (median) | November 1 |
| 90% (late) | November 16 |
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 Posen, IL
Posen, IL frost dates — last frost Apr 10, first frost Nov 1, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Jan 16 to Jan 30Transplant outside: Mar 13 to Mar 27
Start indoors: Jan 30 to Feb 13Transplant outside: Apr 24 to May 8
Start indoors: Jan 30 to Feb 13Transplant outside: Apr 24 to May 8
Start indoors: Feb 13 to Feb 27Transplant outside: Apr 17 to May 1
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 20 to Apr 3Sow outdoors: Mar 13 to Apr 17Plant for fall: Sep 6 to Oct 4
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 13 to Mar 27Sow outdoors: Mar 13 to Mar 27Plant for fall: Aug 23 to Sep 13
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 26 to Aug 16
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 20 to Apr 3Plant for fall: Jul 26 to Aug 16
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 26 to Aug 16
Start indoors: Feb 27 to Mar 13Transplant outside: May 1 to May 15Sow outdoors: May 1 to May 15
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 17 to May 1
Sow outdoors: Feb 27 to Mar 20Plant for fall: Aug 9 to Aug 30
Sow outdoors: Feb 27 to Mar 20Plant for fall: Sep 6 to Sep 27
Sow outdoors: Mar 6 to Apr 17Plant for fall: Sep 20 to Oct 11
Start indoors: Mar 13 to Mar 20Transplant outside: Apr 24 to May 1Sow outdoors: Apr 17 to May 1Plant for fall: Aug 16 to Aug 30
Start indoors: Mar 13 to Mar 20Sow outdoors: Apr 17 to May 1Plant for fall: Aug 23 to Sep 6
Start indoors: Mar 13 to Mar 20Sow outdoors: Apr 17 to May 1
Start indoors: Mar 13 to Mar 20Transplant outside: Apr 24 to May 8
Sow outdoors: Mar 20 to Apr 17Plant for fall: Aug 9 to Aug 23
Sow outdoors: Mar 20 to Apr 17Plant for fall: Aug 23 to Sep 6
Sow outdoors: Mar 20 to Apr 10
Sow outdoors: Mar 27 to Apr 24Plant for fall: Aug 23 to Sep 6
Sow outdoors: Mar 27 to Apr 17Plant for fall: Sep 6 to Sep 27
Sow outdoors: Apr 17 to May 8Plant for fall: Aug 16 to Aug 30
Sow outdoors: Apr 17 to May 1
Transplant outside: Apr 24 to May 15
Plant for fall: Oct 18 to Nov 22
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Posen, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 16 – Jan 30 | Mar 13 – Mar 27 | — | — |
| Peppers | Jan 30 – Feb 13 | Apr 24 – May 8 | — | — |
| Eggplant | Jan 30 – Feb 13 | Apr 24 – May 8 | — | — |
| Tomatoes | Feb 13 – Feb 27 | Apr 17 – May 1 | — | — |
| Lettuce | Feb 13 – Feb 27 | Mar 20 – Apr 3 | Mar 13 – Apr 17 | Sep 6 – Oct 4 |
| Kale | Feb 13 – Feb 27 | Mar 13 – Mar 27 | Mar 13 – Mar 27 | Aug 23 – Sep 13 |
| Broccoli | Feb 13 – Feb 27 | Mar 27 – Apr 10 | — | Jul 26 – Aug 16 |
| Cabbage | Feb 13 – Feb 27 | Mar 20 – Apr 3 | — | Jul 26 – Aug 16 |
| Cauliflower | Feb 13 – Feb 27 | Mar 27 – Apr 10 | — | Jul 26 – Aug 16 |
| Okra | Feb 27 – Mar 13 | May 1 – May 15 | May 1 – May 15 | — |
| Basil | Feb 27 – Mar 13 | Apr 17 – May 1 | — | — |
| Peas | — | — | Feb 27 – Mar 20 | Aug 9 – Aug 30 |
| Spinach | — | — | Feb 27 – Mar 20 | Sep 6 – Sep 27 |
| Radishes | — | — | Mar 6 – Apr 17 | Sep 20 – Oct 11 |
| Cucumbers | Mar 13 – Mar 20 | Apr 24 – May 1 | Apr 17 – May 1 | Aug 16 – Aug 30 |
| Zucchini & Summer Squash | Mar 13 – Mar 20 | — | Apr 17 – May 1 | Aug 23 – Sep 6 |
| Winter Squash & Pumpkins | Mar 13 – Mar 20 | — | Apr 17 – May 1 | — |
| Melons & Watermelon | Mar 13 – Mar 20 | Apr 24 – May 8 | — | — |
| Carrots | — | — | Mar 20 – Apr 17 | Aug 9 – Aug 23 |
| Beets | — | — | Mar 20 – Apr 17 | Aug 23 – Sep 6 |
| Potatoes | — | — | Mar 20 – Apr 10 | — |
| Swiss Chard | — | — | Mar 27 – Apr 24 | Aug 23 – Sep 6 |
| Cilantro | — | — | Mar 27 – Apr 17 | Sep 6 – Sep 27 |
| Green Beans | — | — | Apr 17 – May 8 | Aug 16 – Aug 30 |
| Sweet Corn | — | — | Apr 17 – May 1 | — |
| Sweet Potatoes | — | Apr 24 – May 15 | — | — |
| Garlic | — | — | — | Oct 18 – Nov 22 |
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 Chicago Midway Ap 3sw, IL weather station, 14 km away (elevation 620 ft (189 m)).
Frost dates near Posen
- Robbins Apr 10 · Nov 1
- Markham Apr 23 · Oct 20
- Blue Island Apr 10 · Nov 1
- Harvey Apr 23 · Oct 20
- Midlothian Apr 10 · Nov 1
- Crestwood Apr 10 · Nov 1
- Riverdale Apr 10 · Nov 1
- Oak Forest Apr 23 · Oct 20
- Hazel Crest Apr 23 · Oct 20
- Alsip Apr 10 · Nov 1
Frequently asked questions
When is the last frost in Posen, IL?
The median last spring frost in Posen, IL is April 10. There is still about a 10% chance of frost after April 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Posen, IL?
The median first fall frost is November 1, with about a 10% chance of frost before October 21.
How long is the growing season in Posen, IL?
About 205 days between the median last spring frost and first fall frost.
What planting zone is Posen, IL?
Posen, IL is in USDA hardiness zone 6a.