Hinsdale 4 SW, MT Frost Dates & Growing Season

The two dates every Hinsdale 4 SW garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
May 15
~50% chance of frost after
First fall frost
Sep 26
~50% chance of frost before
Growing season
134 days
frost-free stretch
USDA zone
≈ 5a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost May 3 May 15 May 30
First fall frost Oct 10 Sep 26 Sep 12
Hard freeze (28°F), median last May 5 · first Oct 4

Computed from NOAA 1991–2020 climate normals at the HINSDALE 4 SW 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 Hinsdale 4 SW

Computed from Hinsdale 4 SW's own frost dates. Click any crop for the full zone-5 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Mar 20 – Apr 3 May 22 – May 29
🫑 Peppers Mar 6 – Mar 20 May 29 – Jun 5
🥬 Lettuce Apr 3 – Apr 17 Apr 17 – May 1 Apr 17 – May 15
🫛 Peas Apr 3 – Apr 17
🥕 Carrots Apr 24 – May 15
🥦 Broccoli Mar 27 – Apr 10 Apr 24 – May 8
🥬 Kale Apr 3 – Apr 17 Apr 17 – May 1 Apr 17 – May 1
🥒 Cucumbers Apr 17 – Apr 24 May 22 – May 29 May 22 – May 29
🥒 Zucchini Apr 17 – Apr 24 May 22 – May 29 May 22 – May 29
🫘 Green Beans (Bush) May 22 – May 29
🌽 Sweet Corn May 22 – May 29
🌿 Basil Apr 3 – Apr 17 May 22 – May 29 May 29 – Jun 5
🧄 Garlic Fall: Aug 15 – Sep 12

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 Hinsdale 4 SW's dates automatically after a lookup.

Reading the season in Hinsdale 4 SW

At about 134 frost-free days, Hinsdale 4 SW 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 Hinsdale 4 SW, MT?

The average last spring frost in Hinsdale 4 SW is around May 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 Hinsdale 4 SW, MT?

The average first fall frost in Hinsdale 4 SW arrives around Sep 26. 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 Hinsdale 4 SW?

About 134 frost-free days on average, from May 15 to Sep 26. 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 Hinsdale 4 SW in?

USDA zone 5a 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.