When to plant broccoli in USDA Zone 5a

Plan your broccoli 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: excellent
Broccoli is well suited to Zone 5a. Standard planting dates work with minor adjustments for microclimates.

Key dates

Start seeds indoors
March 20 – April 3
Transplant outdoors
April 10 – May 1
Expected first harvest
June 21 – July 19
Fall planting window
June 16 – July 7
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
hardy
Days to harvest
65 days

Grower notes for Zone 5a

Harvest the central head while buds are still tight; side shoots continue for 4–6 weeks after main cut.

Plant near: onions, beets, chamomile

Keep away from: tomatoes, strawberries

Other brassicas 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.