Trenton, IL frost dates
Last spring frostApr 12median date
First fall frostOct 20median date
Growing season191 daysfrost-free
Hardiness zone6bZone 6b
How Trenton compares
- In 8 years out of 10, the last spring frost in Trenton falls between March 28 and April 28, a 31-day window. The first fall frost falls between October 3 and November 1.
- The median last frost is 5 days earlier than the Illinois median of Apr 17.
- Its 191-day growing season is longer than 62% of the 1,287 Illinois places with a regular frost season (state median 187 days).
- The last frost is 10 days earlier than the zone 6b median of Apr 22. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6b chart.
- The weather station records an average of 93 nights a year at or below 32°F.
- Compared with Florissant, MO, 62 km away, the last frost here is 10 days later than there and the growing season is 25 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 28 |
| 50% (median) | April 12 |
| 10% (safe for tender plants) | April 28 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 3 |
| 50% (median) | October 20 |
| 90% (late) | November 1 |
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 Trenton, IL
Trenton, IL frost dates — last frost Apr 12, first frost Oct 20, zone 6b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Jan 18 to Feb 1Transplant outside: Mar 15 to Mar 29
Start indoors: Feb 1 to Feb 15Transplant outside: Apr 26 to May 10
Start indoors: Feb 1 to Feb 15Transplant outside: Apr 26 to May 10
Start indoors: Feb 15 to Mar 1Transplant outside: Apr 19 to May 3
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 22 to Apr 5Sow outdoors: Mar 15 to Apr 19Plant for fall: Aug 25 to Sep 22
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 15 to Mar 29Sow outdoors: Mar 15 to Mar 29Plant for fall: Aug 11 to Sep 1
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 29 to Apr 12Plant for fall: Jul 14 to Aug 4
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 22 to Apr 5Plant for fall: Jul 14 to Aug 4
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 29 to Apr 12Plant for fall: Jul 14 to Aug 4
Start indoors: Mar 1 to Mar 15Transplant outside: May 3 to May 17Sow outdoors: May 3 to May 17
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 19 to May 3
Sow outdoors: Mar 1 to Mar 22Plant for fall: Jul 28 to Aug 18
Sow outdoors: Mar 1 to Mar 22Plant for fall: Aug 25 to Sep 15
Sow outdoors: Mar 8 to Apr 19Plant for fall: Sep 8 to Sep 29
Start indoors: Mar 15 to Mar 22Transplant outside: Apr 26 to May 3Sow outdoors: Apr 19 to May 3Plant for fall: Aug 4 to Aug 18
Start indoors: Mar 15 to Mar 22Sow outdoors: Apr 19 to May 3Plant for fall: Aug 11 to Aug 25
Start indoors: Mar 15 to Mar 22Sow outdoors: Apr 19 to May 3
Start indoors: Mar 15 to Mar 22Transplant outside: Apr 26 to May 10
Sow outdoors: Mar 22 to Apr 19Plant for fall: Jul 28 to Aug 11
Sow outdoors: Mar 22 to Apr 19Plant for fall: Aug 11 to Aug 25
Sow outdoors: Mar 22 to Apr 12
Sow outdoors: Mar 29 to Apr 26Plant for fall: Aug 11 to Aug 25
Sow outdoors: Mar 29 to Apr 19Plant for fall: Aug 25 to Sep 15
Sow outdoors: Apr 19 to May 10Plant for fall: Aug 4 to Aug 18
Sow outdoors: Apr 19 to May 3
Transplant outside: Apr 26 to May 17
Plant for fall: Oct 6 to Nov 10
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Trenton, IL
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 18 – Feb 1 | Mar 15 – Mar 29 | — | — |
| Peppers | Feb 1 – Feb 15 | Apr 26 – May 10 | — | — |
| Eggplant | Feb 1 – Feb 15 | Apr 26 – May 10 | — | — |
| Tomatoes | Feb 15 – Mar 1 | Apr 19 – May 3 | — | — |
| Lettuce | Feb 15 – Mar 1 | Mar 22 – Apr 5 | Mar 15 – Apr 19 | Aug 25 – Sep 22 |
| Kale | Feb 15 – Mar 1 | Mar 15 – Mar 29 | Mar 15 – Mar 29 | Aug 11 – Sep 1 |
| Broccoli | Feb 15 – Mar 1 | Mar 29 – Apr 12 | — | Jul 14 – Aug 4 |
| Cabbage | Feb 15 – Mar 1 | Mar 22 – Apr 5 | — | Jul 14 – Aug 4 |
| Cauliflower | Feb 15 – Mar 1 | Mar 29 – Apr 12 | — | Jul 14 – Aug 4 |
| Okra | Mar 1 – Mar 15 | May 3 – May 17 | May 3 – May 17 | — |
| Basil | Mar 1 – Mar 15 | Apr 19 – May 3 | — | — |
| Peas | — | — | Mar 1 – Mar 22 | Jul 28 – Aug 18 |
| Spinach | — | — | Mar 1 – Mar 22 | Aug 25 – Sep 15 |
| Radishes | — | — | Mar 8 – Apr 19 | Sep 8 – Sep 29 |
| Cucumbers | Mar 15 – Mar 22 | Apr 26 – May 3 | Apr 19 – May 3 | Aug 4 – Aug 18 |
| Zucchini & Summer Squash | Mar 15 – Mar 22 | — | Apr 19 – May 3 | Aug 11 – Aug 25 |
| Winter Squash & Pumpkins | Mar 15 – Mar 22 | — | Apr 19 – May 3 | — |
| Melons & Watermelon | Mar 15 – Mar 22 | Apr 26 – May 10 | — | — |
| Carrots | — | — | Mar 22 – Apr 19 | Jul 28 – Aug 11 |
| Beets | — | — | Mar 22 – Apr 19 | Aug 11 – Aug 25 |
| Potatoes | — | — | Mar 22 – Apr 12 | — |
| Swiss Chard | — | — | Mar 29 – Apr 26 | Aug 11 – Aug 25 |
| Cilantro | — | — | Mar 29 – Apr 19 | Aug 25 – Sep 15 |
| Green Beans | — | — | Apr 19 – May 10 | Aug 4 – Aug 18 |
| Sweet Corn | — | — | Apr 19 – May 3 | — |
| Sweet Potatoes | — | Apr 26 – May 17 | — | — |
| Garlic | — | — | — | Oct 6 – Nov 10 |
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 Belleville Siu Rsch, IL weather station, 21 km away (elevation 449 ft (137 m)).
Frost dates near Trenton
- Aviston Apr 6 · Oct 29
- Summerfield Apr 12 · Oct 20
- Albers Apr 12 · Oct 20
- Breese Apr 6 · Oct 29
- New Baden Apr 12 · Oct 20
- Germantown Apr 6 · Oct 29
- Lebanon Apr 12 · Oct 20
- New Memphis Apr 12 · Oct 20
- Saint Jacob Apr 12 · Oct 20
- Highland Apr 12 · Oct 20
Frequently asked questions
When is the last frost in Trenton, IL?
The median last spring frost in Trenton, IL is April 12. There is still about a 10% chance of frost after April 28, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Trenton, IL?
The median first fall frost is October 20, with about a 10% chance of frost before October 3.
How long is the growing season in Trenton, IL?
About 191 days between the median last spring frost and first fall frost.
What planting zone is Trenton, IL?
Trenton, IL is in USDA hardiness zone 6b.