When to plant summer squash in USDA Zone 5a

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.

Madison WI, Des Moines, southern MN, central MI. Average last spring frost May 8, first fall frost September 29 — a 144-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
May 15 – June 5
Expected first harvest
July 11 – August 8
Fall planting window
July 21 – August 11
Fall harvest window
September 16 – October 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
24″
Row spacing
48″
Seed depth
1″
Soil temperature
70–90°F
Frost tolerance
tender
Days to harvest
50 days

Grower notes for Zone 5a

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 5a

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.