When to plant collards in USDA Zone 3b

Plan your collards 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
Collards is well suited to Zone 3b. Standard planting dates work with minor adjustments for microclimates.

Key dates

Start seeds indoors
April 13 – April 27
Direct-seed or transplant outdoors
April 20 – May 11
Expected first harvest
June 26 – July 24
Fall planting window
June 11 – July 2
Fall harvest window
August 17 – September 14

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
24″
Seed depth
0.5″
Soil temperature
55–75°F
Frost tolerance
hardy
Days to harvest
60 days

Grower notes for Zone 3b

Southern staple. Flavor sweetens after two hard frosts — fall crop always beats spring for quality.

Plant near: onions, beets, carrots

Keep away from: tomatoes

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.