When to plant peppers in USDA Zone 3b

Plan your peppers 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: good
Peppers is frost-tender, so timing the outdoor transplant to the last frost matters more here than in warmer zones. Row cover buys 2 weeks of head start.

Key dates

Start seeds indoors
March 23 – April 6
Transplant outdoors
June 8 – June 29
Expected first harvest
August 24 – September 21
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
75–85°F
Frost tolerance
tender
Days to harvest
70 days

Grower notes for Zone 3b

Peppers need warmer soil than tomatoes. Wait until nights are consistently above 55°F or fruit set stalls.

Plant near: basil, onions, carrots

Keep away from: fennel, kohlrabi

Other nightshades 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.