When should I plant radishes in ZIP 48226?

In ZIP 48226, the main radishes target is around Apr 7, based on the representative Detroit frost station and USDA zone 6b.

When should I start radishes seeds indoors in 48226?

Radishes is usually direct-sown for ZIP 48226. Use the Apr 7 planting window instead of starting it indoors.

Is this a guaranteed planting date?

No. GrowZone uses frost-date estimates, hardiness zones, and crop timing rules for planning. Local microclimates and current weather can shift the right date.

ZIP 48226 planting calendar

When to plant radishes in Detroit, MI - Zone 6b

Q: When is the first frost in Detroit?

Detroit (ZIP 48226) has an average first fall frost around Oct 15, leaving about 163 frost-free days.

In ZIP 48226, plant radishes around Apr 7; this uses the Detroit frost station, USDA zone 6b, and radishes timing rules.

Your Detroit calendar has a 163-day estimated frost-free season. This estimate uses the representative Detroit frost station, USDA zone 6b, and radishes timing rules.

Source: detroit-metro frost station, USDA zone 6b, last updated 2026-06-28. Verify locally before planting high-value crops because microclimates, current weather, and yard exposure can move the safe date.

Reviewed by GrowZone Editorial. Calculated from the detroit-metro frost station and USDA zone 6b, last updated 2026-06-28.

In the Detroit area, radishes timing follows the Detroit frost window, so the local ZIP date can differ from a broad zone-only calendar.

USDA zone 6b Detroit frost station Michigan State University Extension Updated 2026-06-28

Read the method

Answer first

When to start radishes seeds indoors in Detroit

In ZIP 48226, radishes is usually direct-sown around Apr 7 instead of started indoors.

Radishes is normally direct-sown in Detroit. Use around Apr 7 as the outdoor planting window for ZIP 48226.

Seed starting schedule

Radishes dates for Detroit, MI

Step	Date	How to use it
Direct Sow	April 7, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Detroit?

Detroit (ZIP 48226) has an average last spring frost around May 5.

First frost

When is the first frost in Detroit?

The average first fall frost is around Oct 15, giving about 163 frost-free days.

Season map

Radishes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Direct sow

Apr 7

Harvest

May 5

Frost watch

Sep 17

Reminder workflow

Every date has a next action

Direct sow radishesApr 7

Last frost windowMay 5

First radishes harvest windowMay 5

Last radishes sowing targetSep 17

Signal	Value	Why it matters
Last frost estimate	May 5, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	October 15, 2026	Fall planting counts backward from this date.
Season length	163 days	Longer seasons can support succession crops.
Spacing	1-2 in	Airflow and root space affect yield.
Soil temperature	40 F+	Seeds and transplants stall in cold soil.

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Local data

Why this date changes by ZIP

Detroit frost history and USDA zone 6b shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Michigan State University Extension is the kind of local source to verify against when a crop is expensive, weather is unusual, or your yard has a cold pocket.

Crop note

Radishes timing notes

Fast crop; harvest promptly before roots get woody. Radishes prefers full sun, 1-2 in spacing, and soil near 40 F+.

For fall, count backward from Oct 15. A conservative last sowing target is around Sep 17.