When should I plant basil in ZIP 80012?

In ZIP 80012, the main basil target is around May 15, based on the representative Denver frost station and USDA zone 6a.

When should I start basil seeds indoors in 80012?

Start basil seeds indoors in ZIP 80012 around Mar 31, about 35 days before the May 5 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 80012 planting calendar

When to plant basil in Aurora, CO - Zone 6a

Q: When is the first frost in Aurora?

Aurora (ZIP 80012) has an average first fall frost around Oct 5, leaving about 153 frost-free days.

In ZIP 80012, plant basil around May 15; this uses the Denver frost station, USDA zone 6a, and basil timing rules.

Your Denver calendar has a 153-day estimated frost-free season. This estimate uses the representative Denver frost station, USDA zone 6a, and basil timing rules.

Source: denver-intl frost station, USDA zone 6a, 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 6a Denver frost station Colorado State University Extension Updated 2026-06-28

Read the method

Answer first

When to start basil seeds indoors in Aurora

In ZIP 80012, start basil seeds indoors around Mar 31, about 35 days before the May 5 last-frost estimate.

Start basil seeds indoors in Aurora around Mar 31, about 35 days before the May 5 last-frost estimate.

Seed starting schedule

Basil dates for Aurora, CO

Step	Date	How to use it
Start Indoors	March 31, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	May 15, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	May 15, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Aurora?

Aurora (ZIP 80012) has an average last spring frost around May 5.

First frost

When is the first frost in Aurora?

The average first fall frost is around Oct 5, giving about 153 frost-free days.

Season map

Basil windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Mar 31

Direct sow

May 15

Transplant

May 15

Harvest

Jul 19

Frost watch

Aug 1

Reminder workflow

Every date has a next action

Start basil indoorsMar 31

Last frost windowMay 5

Direct sow basilMay 15

Transplant basilMay 15

First basil harvest windowJul 19

Last basil sowing targetAug 1

Signal	Value	Why it matters
Last frost estimate	May 5, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	October 5, 2026	Fall planting counts backward from this date.
Season length	153 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

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

Colorado 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

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 5. A conservative last sowing target is around Aug 1.