Green Bay, WI Frost Dates & Growing Season

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

Last spring frost
May 7
~50% chance of frost after
First fall frost
Oct 9
~50% chance of frost before
Growing season
155 days
frost-free stretch
USDA zone
5b
2023 hardiness map
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 24 May 7 May 22
First fall frost Oct 25 Oct 9 Sep 23
Hard freeze (28°F), median last Apr 27 · first Oct 25

Computed from NOAA 1991–2020 climate normals at the Green Bay Botanical station (7 km from central Green Bay). "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 Green Bay

Computed from Green Bay'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 12 – Mar 26 May 14 – May 21
🫑 Peppers Feb 26 – Mar 12 May 21 – May 28
🥬 Lettuce Mar 26 – Apr 9 Apr 9 – Apr 23 Apr 9 – May 7
🫛 Peas Mar 26 – Apr 9
🥕 Carrots Apr 16 – May 7
🥦 Broccoli Mar 19 – Apr 2 Apr 16 – Apr 30
🥬 Kale Mar 26 – Apr 9 Apr 9 – Apr 23 Apr 9 – Apr 23
🥒 Cucumbers Apr 9 – Apr 16 May 14 – May 21 May 14 – May 21
🥒 Zucchini Apr 9 – Apr 16 May 14 – May 21 May 14 – May 21
🫘 Green Beans (Bush) May 14 – May 21
🌽 Sweet Corn May 14 – May 21
🌿 Basil Mar 26 – Apr 9 May 14 – May 21 May 21 – May 28
🧄 Garlic Fall: Aug 28 – Sep 25

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 Green Bay's dates automatically after a lookup.

Reading the season in Green Bay

Roughly 155 frost-free days gives Green Bay gardeners room for nearly every common vegetable. Warm-season crops go out after May 7; a fall garden sown in late summer matures comfortably before the Oct 9 frost.

Frequently asked questions

When is the last frost in Green Bay, WI?

The average last spring frost in Green Bay is around May 7, 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 Green Bay, WI?

The average first fall frost in Green Bay arrives around Oct 9. 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 Green Bay?

About 155 frost-free days on average, from May 7 to Oct 9. That fits nearly all common vegetables, though the longest-season melons and sweet potatoes benefit from transplants.

What USDA zone is Green Bay in?

USDA zone 5b 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.