When to plant cauliflower in USDA Zone 3b

Plan your cauliflower planting around local frost risk and soil temperature, then work backward from the harvest week your buyers need. The calendar below is a starting point, not a field-level weather forecast.

Grand Forks & Minot ND, northern MN border counties. Average last spring frost May 25, first fall frost September 10 — a 108-day frost-free season.

Zone fit: excellent
Cauliflower is well suited to Zone 3b. Standard planting dates work with minor adjustments for microclimates.

Key dates

Start seeds indoors
April 6 – April 20
Transplant outdoors
April 27 – May 18
Expected first harvest
July 13 – August 10
Fall planting window
June 11 – July 2
Fall harvest window
August 27 – September 24

Windows are calculated from your zone's average frost dates. Adjust ±1 week for microclimates, elevation, and your own frost records.

Spacing and soil

Plant spacing
18″
Row spacing
30″
Seed depth
0.25″
Soil temperature
55–75°F
Frost tolerance
half-hardy
Days to harvest
70 days

Grower notes for Zone 3b

Blanch heads by folding outer leaves over developing curds when they reach 2 inches, unless growing a self-blanching variety.

Plant near: celery, onions

Keep away from: tomatoes, strawberries

Other brassicas for Zone 3b

Same crop, other zones

Track your own plantings

BAU Farm Intelligence turns these windows into per-field tasks — indoor seed-start reminders, transplant dates, harvest projections — using your farm's actual frost history.