Minnesota planting calendar

When to plant radishes in Minnesota — sow, transplant & harvest dates

Minnesota is mostly USDA zone 4b (range 3a-5a). Dates below are derived from radishes's frost tolerance and Minnesota's frost window — not generic national averages.

Radishes planting timetable for Minnesota

Stage	When in Minnesota	Anchor
Direct-sow outside	late April (April 24)	21 days before the last frost (mid-May)
First harvest (estimate)	late May (May 22)	~28 days from direct sow

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Minnesota's climate shifts the radishes dates

Minnesota's last spring frost averages mid-May and first fall frost late September, which sets the whole planting clock. Minnesota is one of the coldest states in the contiguous US. Cold-hardy varieties and a compressed season define gardening here. Sow early — radishes bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Radishes are the fastest root crop — spring types mature in 22-30 days from direct sowing, making them ideal row-markers alongside slower crops. Sow 2-4 weeks before the last spring frost as soon as soil can be worked; they bolt and become pithy and peppery hot if left too long in warming soil. Succession-sow every 7-10 days for a continuous harvest; daikon and winter types sown in late summer take 50-70 days and tolerate heavier frost.

Frost-risk note

Don't plant before mid-May — a hard freeze can still set young plants back. In the far north near International Falls (zone 3a) the safe date runs a week or two later.

Regional variation within Minnesota

the far north near International Falls (zone 3a) runs roughly 1-2 weeks behind the state average; the Twin Cities metro and far south (zone 5a) can plant 1-2 weeks earlier.

Minneapolis — USDA zone 5a
Saint Paul — USDA zone 5a
Duluth — USDA zone 4b
Rochester — USDA zone 4b

What else to plant in Minnesota around then

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 7-29 °C (45-85 °F).
Spacing: 2-3 inches (5-8 cm) between plants.
Days to harvest: ~28 days from planting out.

Frequently asked questions

When is the best time to plant radishes in Minnesota?

In Minnesota (mostly USDA zone 4b), direct-sow radishes late April (before the last frost, mid-May), and harvest from late May. Radishes are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

What USDA zone is Minnesota?

Most of Minnesota sits in USDA hardiness zone 4b, with the state spanning roughly 3a-5a from the far north near International Falls (zone 3a) to the Twin Cities metro and far south (zone 5a). The last spring frost averages mid-May and the first fall frost late September.

Can you grow radishes in Minnesota?

Yes. Minnesota's dominant zone 4b supports radishes — the key is timing. Radishes are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

Does the planting date change across Minnesota?

the far north near International Falls (zone 3a) runs roughly 1-2 weeks behind the state average; the Twin Cities metro and far south (zone 5a) can plant 1-2 weeks earlier.

What else can I plant in Minnesota around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.