When to plant broccoli in USDA Zone 5b

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.

Chicago, Des Moines suburbs, central IL, upstate NY. Average last spring frost May 1, first fall frost October 6 — a 158-day frost-free season.

Zone fit: excellent
Broccoli is well suited to Zone 5b. Standard planting dates work with minor adjustments for microclimates.

Key dates

Start seeds indoors
March 13 – March 27
Transplant outdoors
April 3 – April 24
Expected first harvest
June 14 – July 12
Fall planting window
June 23 – July 14
Fall harvest window
September 3 – October 1

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 5b

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 5b

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.