Illinois Planting Guide & Growing Season
Illinois is in USDA hardiness zone with a growing season of 180 days. The average last spring frost is Apr 1 - May 1 and the average first fall frost is Oct 1 - Oct 31.
Growing Conditions in Illinois
How Illinois Compares
Compare Illinois's growing conditions with states that have similar climates.
| State | USDA Zone | Last Frost | First Frost | Season (days) |
|---|---|---|---|---|
| Illinois (IL) | Apr 1 - May 1 | Oct 1 - Oct 31 | 180 | |
| Alabama (AL) | Mar 1 - Apr 1 | Oct 25 - Nov 15 | 220 | |
| Alaska (AK) | May 15 - Jun 15 | Aug 15 - Sep 15 | 105 | |
| Arizona (AZ) | Feb 1 - Apr 15 | Oct 15 - Dec 15 | 270 | |
| Arkansas (AR) | Mar 15 - Apr 15 | Oct 15 - Nov 1 | 210 | |
| California (CA) | Jan 15 - Apr 15 | Oct 15 - Dec 31 | 290 |
Frequently Asked Questions About Gardening in Illinois
When should I start seeds indoors in Illinois?
In Illinois, the average last frost date is Apr 1 - May 1. Start most seeds indoors 6-8 weeks before this date. The USDA hardiness zone for Illinois is undefined, with a growing season of approximately 180 days.
What USDA hardiness zone is Illinois?
Illinois falls in USDA hardiness zones undefined. This affects which perennial plants will survive winter and influences optimal planting times.
When is the first frost in Illinois?
The average first frost date in Illinois is Oct 1 - Oct 31. Plan to harvest cold-sensitive crops before this date or protect them with row covers.
How long is the growing season in Illinois?
Illinois has an average growing season of 180 days, from the last frost (Apr 1 - May 1) to first frost (Oct 1 - Oct 31). This moderate season works well for most common vegetables.
Plan Your Garden
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