When to plant summer squash in USDA Zone 3b

Plan your summer squash 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
Summer squash 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

Direct-seed outdoors
June 1 – June 22
Expected first harvest
July 28 – August 25
Fall planting window
July 2 – July 23
Fall harvest window
August 28 – September 25

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
24″
Row spacing
48″
Seed depth
1″
Soil temperature
70–90°F
Frost tolerance
tender
Days to harvest
50 days

Grower notes for Zone 3b

Scout for squash bugs and squash vine borer weekly starting at bloom. Row cover until first female flower.

Plant near: corn, beans, nasturtium

Keep away from: potatoes

Other cucurbits 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.