When to Plant Peppers in Illinois: Spring and Fall Dates by Region
What Illinois’s extension calendar says about peppers, copied region by region, plus the frost record at Chicago O'Hare International Airport, Peoria Greater Peoria Airport, and Springfield Capital Airport.
Updated
Figures checked against their sources on ; next check .
The pepper entry under the heading “Pepper from Transplant” in Illinois’s calendar is read across 3 regions. Reading down the first date column, Central Illinois leads at May 10 and Northern Illinois trails at June 15.
What University of Illinois Extension prints for peppers
The page adds this line for the row: “Sow 24" apart.”
| Region | First planting | Second planting |
|---|---|---|
| Northern Illinois | June 15 to July 30 | — |
| Central Illinois | May 10 to July 15 | — |
| Southern Illinois | May 15 to June 30 | — |
Reading the University of Illinois Extension table
Southern gardeners can generally start two weeks earlier than central Illinois and harvest for about two weeks longer; northern Illinois can plant about two weeks later than central, the page says. Where a crop lists two ranges, the page says it can be planted and harvested twice, for a summer and a fall crop.
Starting peppers indoors
Indoor sowing is the one part of the job no state table above settles. The University of New Hampshire gives 8 to 10 weeks between sowing and transplanting.
Peppers take longer than tomatoes in every source that gives both: UMN says 9 weeks and UGA 8, against 5 to 6 and 6 for tomatoes. NDSU and Montana State, saved here for tomatoes only, say nothing about peppers.
Once the seedlings are ready, UNH says peppers are safe to set out 2 weeks after the last frost, after hardening off.
| Source | What it says |
|---|---|
| University of New Hampshire | 8 to 10 weeks from seed to transplant; 2 weeks after the last frost is safe to set out |
| University of Minnesota | Mid-March in Minnesota, 9 weeks indoors |
| NC State | Any transplant: seed 6 to 8 weeks before setting out (central North Carolina calendar) |
| University of Georgia | 8 weeks from seed to transplant size (middle Georgia calendar) |
Frost dates for Illinois cities
Each date below is NOAA’s 50% level, meaning the last spring 32°F night lands on or after it in half the years, and the first fall night lands on or before it in half. The tool linked beside each city shows the other nine levels.
Regions in the last column come from the source’s wording, never from our reading of a map.
| Station | Last spring 32°F | First fall 32°F | Region in Illinois’s calendar |
|---|---|---|---|
| Chicago O'Hare International Airport, Illinois | April 16 | October 28 | Northern Illinois |
| Peoria Greater Peoria Airport, Illinois | April 16 | October 23 | Not stated by the source |
| Springfield Capital Airport, Illinois | April 14 | October 20 | Not stated by the source |
| Carbondale Southern Il Airport, Illinois | April 9 | October 22 | Not stated by the source |
| Rockford Greater Rockford Airport, Illinois | April 24 | October 17 | Not stated by the source |
Worked example
Pick Chicago O'Hare International Airport, Illinois as the garden. Half of recent years saw their last spring 32°F night by April 16, and half saw their first fall one by October 28.
Northern Illinois lists June 15 to July 30. Counting from the frost date, that is an opening 60 days after it and a close 105 days after it.
This is arithmetic on two printed figures, not a forecast: it moves with the year, and your own garden can sit weeks away from the station. Look up the station nearest you in the frost dates tool and repeat the subtraction.
Before you rely on these dates
The page tells readers to always confirm dates with the seed packet or plant tag.
Pencil the printed dates into a calendar, then adjust them after you have watched your own garden for a season.
Sources (6)
- University of Illinois Extension (Kelly Allsup), When to Plant, Home Vegetable Gardening, updated August 2025 extension.illinois.edu
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020, annual and seasonal normals (frost/freeze probabilities by station) ncei.noaa.gov
- University of New Hampshire Cooperative Extension, Growing Vegetables: When to Plant Your Vegetable Garden (fact sheet) extension.unh.edu
- University of Minnesota Extension, Starting seeds indoors (page reviewed 2026) extension.umn.edu
- NC State Extension (Bradley, Gunter, Sherk and Driscoll), Central North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs, AG-756-01, published July 8, 2016 content.ces.ncsu.edu
- University of Georgia Cooperative Extension (Bob Westerfield), Vegetable Garden Calendar, Circular 943, published with full review March 10, 2026 extension.uga.edu