Boise, ID Frost Dates & Growing Season

The two dates every Boise garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Apr 24
~50% chance of frost after
First fall frost
Oct 21
~50% chance of frost before
Growing season
180 days
frost-free stretch
USDA zone
7a
2023 hardiness map
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 4 Apr 24 May 9
First fall frost Nov 5 Oct 21 Oct 5
Hard freeze (28°F), median last Apr 2 · first Oct 31

Computed from NOAA 1991–2020 climate normals at the Boise Air Terminal station (7 km from central Boise). "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Boise

Computed from Boise's own frost dates. Click any crop for the full zone-7 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Feb 27 – Mar 13 May 1 – May 8
🫑 Peppers Feb 13 – Feb 27 May 8 – May 15
🥬 Lettuce Mar 13 – Mar 27 Mar 27 – Apr 10 Mar 27 – Apr 24
🫛 Peas Mar 13 – Mar 27
🥕 Carrots Apr 3 – Apr 24
🥦 Broccoli Mar 6 – Mar 20 Apr 3 – Apr 17
🥬 Kale Mar 13 – Mar 27 Mar 27 – Apr 10 Mar 27 – Apr 10
🥒 Cucumbers Mar 27 – Apr 3 May 1 – May 8 May 1 – May 8
🥒 Zucchini Mar 27 – Apr 3 May 1 – May 8 May 1 – May 8
🫘 Green Beans (Bush) May 1 – May 8
🌽 Sweet Corn May 1 – May 8
🌿 Basil Mar 13 – Mar 27 May 1 – May 8 May 8 – May 15
🧄 Garlic Fall: Sep 9 – Oct 7

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Boise's dates automatically after a lookup.

Reading the season in Boise

Roughly 180 frost-free days gives Boise gardeners room for nearly every common vegetable. Warm-season crops go out after Apr 24; a fall garden sown in late summer matures comfortably before the Oct 21 frost.

Frequently asked questions

When is the last frost in Boise, ID?

The average last spring frost in Boise is around Apr 24, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Boise, ID?

The average first fall frost in Boise arrives around Oct 21. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Boise?

About 180 frost-free days on average, from Apr 24 to Oct 21. That fits nearly all common vegetables, though the longest-season melons and sweet potatoes benefit from transplants.

What USDA zone is Boise in?

USDA zone 7a on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.