When to plant radishes in USDA Zone 3b

Plan your radishes 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.

Grand Forks & Minot ND, northern MN border counties. Average last spring frost May 25, first fall frost September 10 — a 108-day frost-free season.

Zone fit: excellent
Radishes is well suited to Zone 3b. Standard planting dates work with minor adjustments for microclimates.

Key dates

Direct-seed outdoors
April 20 – May 11
Expected first harvest
May 25 – June 22
Fall planting window
July 23 – August 13
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
1″
Row spacing
12″
Seed depth
0.5″
Soil temperature
45–70°F
Frost tolerance
hardy
Days to harvest
28 days

Grower notes for Zone 3b

Fastest crop in the garden. Interplant with slow germinators like carrots to mark rows.

Plant near: cucumbers, carrots, lettuce

Keep away from: hyssop

Other root crops for Zone 3b

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.