Medicine Lake 3 SE, MT Frost Dates & Growing Season

The two dates every Medicine Lake 3 SE garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
May 16
~50% chance of frost after
First fall frost
Sep 18
~50% chance of frost before
Growing season
125 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 4 May 16 May 30
First fall frost Sep 28 Sep 18 Sep 7
Hard freeze (28°F), median last May 5 · first Sep 25

Computed from NOAA 1991–2020 climate normals at the MEDICINE LAKE 3 SE 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 Medicine Lake 3 SE

Computed from Medicine Lake 3 SE'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 Mar 21 – Apr 4 May 23 – May 30
🫑 Peppers Mar 7 – Mar 21 May 30 – Jun 6
🥬 Lettuce Apr 4 – Apr 18 Apr 18 – May 2 Apr 18 – May 16
🫛 Peas Apr 4 – Apr 18
🥕 Carrots Apr 25 – May 16
🥦 Broccoli Mar 28 – Apr 11 Apr 25 – May 9
🥬 Kale Apr 4 – Apr 18 Apr 18 – May 2 Apr 18 – May 2
🥒 Cucumbers Apr 18 – Apr 25 May 23 – May 30 May 23 – May 30
🥒 Zucchini Apr 18 – Apr 25 May 23 – May 30 May 23 – May 30
🫘 Green Beans (Bush) May 23 – May 30
🌽 Sweet Corn May 23 – May 30
🌿 Basil Apr 4 – Apr 18 May 23 – May 30 May 30 – Jun 6
🧄 Garlic Fall: Aug 7 – Sep 4

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 Medicine Lake 3 SE's dates automatically after a lookup.

Reading the season in Medicine Lake 3 SE

At about 125 frost-free days, Medicine Lake 3 SE 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 Medicine Lake 3 SE, MT?

The average last spring frost in Medicine Lake 3 SE is around May 16, 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 Medicine Lake 3 SE, MT?

The average first fall frost in Medicine Lake 3 SE arrives around Sep 18. 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 Medicine Lake 3 SE?

About 125 frost-free days on average, from May 16 to Sep 18. 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 Medicine Lake 3 SE 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.