When to plant swiss chard in USDA Zone 4b

Plan your swiss chard 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
Swiss chard is well suited to Zone 4b. Standard planting dates work with minor adjustments for microclimates.

Key dates

Start seeds indoors
April 10 – April 24
Direct-seed or transplant outdoors
April 17 – May 8
Expected first harvest
June 18 – July 16
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
10″
Row spacing
18″
Seed depth
0.5″
Soil temperature
50–75°F
Frost tolerance
hardy
Days to harvest
55 days

Grower notes for Zone 4b

Cut-and-come-again crop. A spring planting can produce well into fall with cool weather and consistent water.

Plant near: beans, onions

Keep away from: corn

Other leafy greens 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.