When to plant radishes in USDA Zone 4a

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.

Fargo ND, northern MN, northern WI, northern ME. Average last spring frost May 22, first fall frost September 15 — a 116-day frost-free season.

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

Key dates

Direct-seed outdoors
April 17 – May 8
Expected first harvest
May 22 – June 19
Fall planting window
July 28 – August 18
Fall harvest window
September 1 – September 29

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 4a

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 4a

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.