Judith Gap, MT Frost Dates & Growing Season

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

Last spring frost
Jun 1
~50% chance of frost after
First fall frost
Sep 15
~50% chance of frost before
Growing season
106 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 17 Jun 1 Jun 16
First fall frost Sep 28 Sep 15 Aug 31
Hard freeze (28°F), median last May 15 · first Sep 28

Computed from NOAA 1991–2020 climate normals at the JUDITH GAP 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 Judith Gap

Computed from Judith Gap'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 6 – Apr 20 Jun 8 – Jun 15
🫑 Peppers Mar 23 – Apr 6 Jun 15 – Jun 22
🥬 Lettuce Apr 20 – May 4 May 4 – May 18 May 4 – Jun 1
🫛 Peas Apr 20 – May 4
🥕 Carrots May 11 – Jun 1
🥦 Broccoli Apr 13 – Apr 27 May 11 – May 25
🥬 Kale Apr 20 – May 4 May 4 – May 18 May 4 – May 18
🥒 Cucumbers May 4 – May 11 Jun 8 – Jun 15 Jun 8 – Jun 15
🥒 Zucchini May 4 – May 11 Jun 8 – Jun 15 Jun 8 – Jun 15
🫘 Green Beans (Bush) Jun 8 – Jun 15
🌽 Sweet Corn Jun 8 – Jun 15
🌿 Basil Apr 20 – May 4 Jun 8 – Jun 15 Jun 15 – Jun 22
🧄 Garlic Fall: Aug 4 – Sep 1

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 Judith Gap's dates automatically after a lookup.

Reading the season in Judith Gap

At about 106 frost-free days, Judith Gap 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 Judith Gap, MT?

The average last spring frost in Judith Gap is around Jun 1, 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 Judith Gap, MT?

The average first fall frost in Judith Gap arrives around Sep 15. 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 Judith Gap?

About 106 frost-free days on average, from Jun 1 to Sep 15. 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 Judith Gap 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.