Duncan, OK Frost Dates & Growing Season

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

Last spring frost
Mar 25
~50% chance of frost after
First fall frost
Nov 7
~50% chance of frost before
Growing season
227 days
frost-free stretch
USDA zone
≈ 7b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Mar 3 Mar 25 Apr 12
First fall frost Nov 23 Nov 7 Oct 22
Hard freeze (28°F), median last Mar 11 · first Nov 16

Computed from NOAA 1991–2020 climate normals at the DUNCAN 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 Duncan

Computed from Duncan's own frost dates. Click any crop for the full zone-7 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Jan 28 – Feb 11 Apr 1 – Apr 8
🫑 Peppers Jan 14 – Jan 28 Apr 8 – Apr 15
🥬 Lettuce Feb 11 – Feb 25 Feb 25 – Mar 11 Feb 25 – Mar 25
🫛 Peas Feb 11 – Feb 25
🥕 Carrots Mar 4 – Mar 25
🥦 Broccoli Feb 4 – Feb 18 Mar 4 – Mar 18
🥬 Kale Feb 11 – Feb 25 Feb 25 – Mar 11 Feb 25 – Mar 11
🥒 Cucumbers Feb 25 – Mar 4 Apr 1 – Apr 8 Apr 1 – Apr 8
🥒 Zucchini Feb 25 – Mar 4 Apr 1 – Apr 8 Apr 1 – Apr 8
🫘 Green Beans (Bush) Apr 1 – Apr 8
🌽 Sweet Corn Apr 1 – Apr 8
🌿 Basil Feb 11 – Feb 25 Apr 1 – Apr 8 Apr 8 – Apr 15
🧄 Garlic Fall: Sep 26 – Oct 24

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 Duncan's dates automatically after a lookup.

Reading the season in Duncan

With roughly 227 frost-free days, Duncan gardens fit long-season crops — melons, winter squash, sweet potatoes — with room left for spring and fall rounds of greens and roots. The first frost around Nov 7 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Duncan, OK?

The average last spring frost in Duncan is around Mar 25, 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 Duncan, OK?

The average first fall frost in Duncan arrives around Nov 7. 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 Duncan?

About 227 frost-free days on average, from Mar 25 to Nov 7. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Duncan in?

USDA zone 7b 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.