Milbank 4 NW, SD Frost Dates & Growing Season

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

Last spring frost
May 2
~50% chance of frost after
First fall frost
Oct 4
~50% chance of frost before
Growing season
155 days
frost-free stretch
USDA zone
≈ 4b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 20 May 2 May 15
First fall frost Oct 16 Oct 4 Sep 22
Hard freeze (28°F), median last Apr 24 · first Oct 12

Computed from NOAA 1991–2020 climate normals at the MILBANK 4 NW 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 Milbank 4 NW

Computed from Milbank 4 NW'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 7 – Mar 21 May 9 – May 16
🫑 Peppers Feb 21 – Mar 7 May 16 – May 23
🥬 Lettuce Mar 21 – Apr 4 Apr 4 – Apr 18 Apr 4 – May 2
🫛 Peas Mar 21 – Apr 4
🥕 Carrots Apr 11 – May 2
🥦 Broccoli Mar 14 – Mar 28 Apr 11 – Apr 25
🥬 Kale Mar 21 – Apr 4 Apr 4 – Apr 18 Apr 4 – Apr 18
🥒 Cucumbers Apr 4 – Apr 11 May 9 – May 16 May 9 – May 16
🥒 Zucchini Apr 4 – Apr 11 May 9 – May 16 May 9 – May 16
🫘 Green Beans (Bush) May 9 – May 16
🌽 Sweet Corn May 9 – May 16
🌿 Basil Mar 21 – Apr 4 May 9 – May 16 May 16 – May 23
🧄 Garlic Fall: Aug 23 – Sep 20

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 Milbank 4 NW's dates automatically after a lookup.

Reading the season in Milbank 4 NW

Roughly 155 frost-free days gives Milbank 4 NW gardeners room for nearly every common vegetable. Warm-season crops go out after May 2; a fall garden sown in late summer matures comfortably before the Oct 4 frost.

Frequently asked questions

When is the last frost in Milbank 4 NW, SD?

The average last spring frost in Milbank 4 NW is around May 2, 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 Milbank 4 NW, SD?

The average first fall frost in Milbank 4 NW arrives around Oct 4. 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 Milbank 4 NW?

About 155 frost-free days on average, from May 2 to Oct 4. That fits nearly all common vegetables, though the longest-season melons and sweet potatoes benefit from transplants.

What USDA zone is Milbank 4 NW 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.