When should I plant tomatoes in ZIP 80903?

In ZIP 80903, the main tomatoes target is around May 22, based on the representative Colorado Springs frost station and USDA zone 6a.

When should I start tomatoes seeds indoors in 80903?

Start tomatoes seeds indoors in ZIP 80903 around Apr 3, about 42 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 tomatoes 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 tomatoes around May 22; this uses the Colorado Springs frost station, USDA zone 6a, and tomatoes 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 tomatoes 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 tomatoes seeds indoors in Colorado Springs

In ZIP 80903, start tomatoes seeds indoors around Apr 3, about 42 days before the May 15 last-frost estimate.

Start tomatoes seeds indoors in Colorado Springs around Apr 3, about 42 days before the May 15 last-frost estimate.

Seed starting schedule

Tomatoes dates for Colorado Springs, CO

Step	Date	How to use it
Start Indoors	April 3, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	May 22, 2026	Move hardened-off seedlings outside after the frost-risk 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

Tomatoes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Apr 3

Transplant

May 22

Harvest

Aug 8

Frost watch

Jul 15

Reminder workflow

Every date has a next action

Start tomatoes indoorsApr 3

Last frost windowMay 15

Transplant tomatoesMay 22

Last tomatoes sowing targetJul 15

First tomatoes harvest windowAug 8

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	18-24 in	Airflow and root space affect yield.
Soil temperature	60 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

Tomatoes timing notes

Harden seedlings off for a week before transplanting. Tomatoes prefers full sun, 18-24 in spacing, and soil near 60 F+.

For fall, count backward from Oct 1. A conservative last sowing target is around Jul 15.