When to plant kale in USDA Zone 4b

Plan your kale 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.

Minneapolis, Duluth, central WI, northern VT/NH. Average last spring frost May 15, first fall frost September 22 — a 130-day frost-free season.

Zone fit: excellent
Kale is well suited to Zone 4b. Standard planting dates work with minor adjustments for microclimates.

Key dates

Start seeds indoors
April 3 – April 17
Direct-seed or transplant outdoors
April 10 – May 1
Expected first harvest
June 11 – July 9
Fall planting window
July 7 – July 28
Fall harvest window
September 7 – October 5

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
12″
Row spacing
24″
Seed depth
0.5″
Soil temperature
55–75°F
Frost tolerance
hardy
Days to harvest
55 days

Grower notes for Zone 4b

Harvest outer leaves and leave the growing tip — a single plant can produce for 3+ months.

Plant near: beets, onions, herbs

Keep away from: tomatoes

Other brassicas for Zone 4b

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.