Tetonia Exp Stn, ID Frost Dates & Growing Season

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

Last spring frost
Jun 15
~50% chance of frost after
First fall frost
Sep 7
~50% chance of frost before
Growing season
84 days
frost-free stretch
USDA zone
≈ 4b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost May 24 Jun 15 Jun 29
First fall frost Sep 23 Sep 7 Aug 24
Hard freeze (28°F), median last May 21 · first Sep 20

Computed from NOAA 1991–2020 climate normals at the TETONIA EXP STN station. "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 Tetonia Exp Stn

Computed from Tetonia Exp Stn's own frost dates. Click any crop for the full zone-4 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Apr 20 – May 4 Jun 22 – Jun 29
🫑 Peppers Apr 6 – Apr 20 Jun 29 – Jul 6
🥬 Lettuce May 4 – May 18 May 18 – Jun 1 May 18 – Jun 15
🫛 Peas May 4 – May 18
🥕 Carrots May 25 – Jun 15
🥦 Broccoli Apr 27 – May 11 May 25 – Jun 8
🥬 Kale May 4 – May 18 May 18 – Jun 1 May 18 – Jun 1
🥒 Cucumbers May 18 – May 25 Jun 22 – Jun 29 Jun 22 – Jun 29
🥒 Zucchini May 18 – May 25 Jun 22 – Jun 29 Jun 22 – Jun 29
🫘 Green Beans (Bush) Jun 22 – Jun 29
🌽 Sweet Corn Jun 22 – Jun 29
🌿 Basil May 4 – May 18 Jun 22 – Jun 29 Jun 29 – Jul 6
🧄 Garlic Fall: Jul 27 – Aug 24

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 Tetonia Exp Stn's dates automatically after a lookup.

Reading the season in Tetonia Exp Stn

At about 84 frost-free days, Tetonia Exp Stn rewards efficiency: start warm-season crops indoors, favor short-season varieties, and lean on cold-tolerant crops — peas, kale, roots — that shrug off the shoulder-season frosts on either end.

Frequently asked questions

When is the last frost in Tetonia Exp Stn, ID?

The average last spring frost in Tetonia Exp Stn is around Jun 15, 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 Tetonia Exp Stn, ID?

The average first fall frost in Tetonia Exp Stn arrives around Sep 7. 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 Tetonia Exp Stn?

About 84 frost-free days on average, from Jun 15 to Sep 7. That favors short-season varieties and transplants for warm-season crops, with cool-season vegetables doing the heavy lifting in spring and fall.

What USDA zone is Tetonia Exp Stn in?

USDA zone 4b 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.