When should I plant radishes in ZIP 46204?

In ZIP 46204, the main radishes target is around Mar 28, based on the representative Indianapolis frost station and USDA zone 6b.

When should I start radishes seeds indoors in 46204?

Radishes is usually direct-sown for ZIP 46204. Use the Mar 28 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 46204 planting calendar

When to plant radishes in Indianapolis, IN - Zone 6b

Q: When is the first frost in Indianapolis?

Indianapolis (ZIP 46204) has an average first fall frost around Oct 15, leaving about 173 frost-free days.

In ZIP 46204, plant radishes around Mar 28; this uses the Indianapolis frost station, USDA zone 6b, and radishes timing rules.

Your Indianapolis calendar has a 173-day estimated frost-free season. This estimate uses the representative Indianapolis frost station, USDA zone 6b, and radishes timing rules.

Source: indianapolis-intl 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.

USDA zone 6b Indianapolis frost station Purdue Extension Updated 2026-06-28

Read the method

Answer first

When to start radishes seeds indoors in Indianapolis

In ZIP 46204, radishes is usually direct-sown around Mar 28 instead of started indoors.

Radishes is normally direct-sown in Indianapolis. Use around Mar 28 as the outdoor planting window for ZIP 46204.

Seed starting schedule

Radishes dates for Indianapolis, IN

Step	Date	How to use it
Direct Sow	March 28, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Indianapolis?

Indianapolis (ZIP 46204) has an average last spring frost around Apr 25.

First frost

When is the first frost in Indianapolis?

The average first fall frost is around Oct 15, giving about 173 frost-free days.

Season map

Radishes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Direct sow

Mar 28

Harvest

Apr 25

Frost watch

Sep 17

Reminder workflow

Every date has a next action

Direct sow radishesMar 28

Last frost windowApr 25

First radishes harvest windowApr 25

Last radishes sowing targetSep 17

Signal	Value	Why it matters
Last frost estimate	April 25, 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	173 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

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

Purdue 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.