When should I plant basil in ZIP 46204?

In ZIP 46204, the main basil target is around May 5, based on the representative Indianapolis frost station and USDA zone 6b.

When should I start basil seeds indoors in 46204?

Start basil seeds indoors in ZIP 46204 around Mar 21, about 35 days before the Apr 25 last-frost estimate.

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 basil 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 basil around May 5; this uses the Indianapolis frost station, USDA zone 6b, and basil 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 basil 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 basil seeds indoors in Indianapolis

In ZIP 46204, start basil seeds indoors around Mar 21, about 35 days before the Apr 25 last-frost estimate.

Start basil seeds indoors in Indianapolis around Mar 21, about 35 days before the Apr 25 last-frost estimate.

Seed starting schedule

Basil dates for Indianapolis, IN

Step	Date	How to use it
Start Indoors	March 21, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	May 5, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	May 5, 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

Basil windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Mar 21

Direct sow

May 5

Transplant

May 5

Harvest

Jul 9

Frost watch

Aug 11

Reminder workflow

Every date has a next action

Start basil indoorsMar 21

Last frost windowApr 25

Direct sow basilMay 5

Transplant basilMay 5

First basil harvest windowJul 9

Last basil sowing targetAug 11

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	10-12 in	Airflow and root space affect yield.
Soil temperature	65 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

Basil timing notes

Pinch the growing tips early for fuller plants. Basil prefers full sun, 10-12 in spacing, and soil near 65 F+.

For fall, count backward from Oct 15. A conservative last sowing target is around Aug 11.