When should I plant basil in ZIP 80903?

In ZIP 80903, the main basil target is around May 25, based on the representative Colorado Springs frost station and USDA zone 6a.

When should I start basil seeds indoors in 80903?

Start basil seeds indoors in ZIP 80903 around Apr 10, about 35 days before the May 15 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 80903 planting calendar

When to plant basil in Colorado Springs, CO - Zone 6a

Q: When is the first frost in Colorado Springs?

Colorado Springs (ZIP 80903) has an average first fall frost around Oct 1, leaving about 139 frost-free days.

In ZIP 80903, plant basil around May 25; this uses the Colorado Springs frost station, USDA zone 6a, and basil timing rules.

Your Colorado Springs calendar has a 139-day estimated frost-free season. This estimate uses the representative Colorado Springs frost station, USDA zone 6a, and basil timing rules.

Source: colorado-springs-muni 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 Colorado Springs frost station Colorado State University Extension Updated 2026-06-28

Read the method

Answer first

When to start basil seeds indoors in Colorado Springs

In ZIP 80903, start basil seeds indoors around Apr 10, about 35 days before the May 15 last-frost estimate.

Start basil seeds indoors in Colorado Springs around Apr 10, about 35 days before the May 15 last-frost estimate.

Seed starting schedule

Basil dates for Colorado Springs, CO

Step	Date	How to use it
Start Indoors	April 10, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	May 25, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	May 25, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Colorado Springs?

Colorado Springs (ZIP 80903) has an average last spring frost around May 15.

First frost

When is the first frost in Colorado Springs?

The average first fall frost is around Oct 1, giving about 139 frost-free days.

Season map

Basil windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Apr 10

Direct sow

May 25

Transplant

May 25

Harvest

Jul 29

Frost watch

Jul 28

Reminder workflow

Every date has a next action

Start basil indoorsApr 10

Last frost windowMay 15

Direct sow basilMay 25

Transplant basilMay 25

Last basil sowing targetJul 28

First basil harvest windowJul 29

Signal	Value	Why it matters
Last frost estimate	May 15, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	October 1, 2026	Fall planting counts backward from this date.
Season length	139 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

Colorado Springs 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 1. A conservative last sowing target is around Jul 28.