Idaho Planting Guide & Growing Season
Idaho is in USDA hardiness zone with a growing season of 140 days. The average last spring frost is Apr 15 - Jun 15 and the average first fall frost is Sep 1 - Oct 15.
Growing Conditions in Idaho
How Idaho Compares
Compare Idaho's growing conditions with states that have similar climates.
| State | USDA Zone | Last Frost | First Frost | Season (days) |
|---|---|---|---|---|
| Idaho (ID) | Apr 15 - Jun 15 | Sep 1 - Oct 15 | 140 | |
| 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 Idaho
When should I start seeds indoors in Idaho?
In Idaho, the average last frost date is Apr 15 - Jun 15. Start most seeds indoors 6-8 weeks before this date. The USDA hardiness zone for Idaho is undefined, with a growing season of approximately 140 days.
What USDA hardiness zone is Idaho?
Idaho 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 Idaho?
The average first frost date in Idaho is Sep 1 - Oct 15. Plan to harvest cold-sensitive crops before this date or protect them with row covers.
How long is the growing season in Idaho?
Idaho has an average growing season of 140 days, from the last frost (Apr 15 - Jun 15) to first frost (Sep 1 - Oct 15). This shorter season requires starting many crops indoors and choosing quick-maturing varieties.
Plan Your Garden
Use our seed starting calculator to get personalized planting dates, or browse all states.