Jackson, WY Frost Dates & Growing Season

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

Last spring frost
Jun 20
~50% chance of frost after
First fall frost
Aug 31
~50% chance of frost before
Growing season
72 days
frost-free stretch
USDA zone
4b
2023 hardiness map
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Jun 5 Jun 20 Jul 9
First fall frost Sep 13 Aug 31 Aug 12
Hard freeze (28°F), median last Jun 2 · first Sep 13

Computed from NOAA 1991–2020 climate normals at the Moose station (20 km from central Jackson). "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 Jackson

Computed from Jackson'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 25 – May 9 Jun 27 – Jul 4
🫑 Peppers Apr 11 – Apr 25 Jul 4 – Jul 11
🥬 Lettuce May 9 – May 23 May 23 – Jun 6 May 23 – Jun 20
🫛 Peas May 9 – May 23
🥕 Carrots May 30 – Jun 20
🥦 Broccoli May 2 – May 16 May 30 – Jun 13
🥬 Kale May 9 – May 23 May 23 – Jun 6 May 23 – Jun 6
🥒 Cucumbers May 23 – May 30 Jun 27 – Jul 4 Jun 27 – Jul 4
🥒 Zucchini May 23 – May 30 Jun 27 – Jul 4 Jun 27 – Jul 4
🫘 Green Beans (Bush) Jun 27 – Jul 4
🌽 Sweet Corn Jun 27 – Jul 4
🌿 Basil May 9 – May 23 Jun 27 – Jul 4 Jul 4 – Jul 11
🧄 Garlic Fall: Jul 20 – Aug 17

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 Jackson's dates automatically after a lookup.

Reading the season in Jackson

At about 72 frost-free days, Jackson 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 Jackson, WY?

The average last spring frost in Jackson is around Jun 20, 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 Jackson, WY?

The average first fall frost in Jackson arrives around Aug 31. 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 Jackson?

About 72 frost-free days on average, from Jun 20 to Aug 31. 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 Jackson 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.