When should I plant tomatoes in ZIP 85201?

In ZIP 85201, the main tomatoes target is around Feb 12, based on the representative Phoenix frost station and USDA zone 10a.

When should I start tomatoes seeds indoors in 85201?

Start tomatoes seeds indoors in ZIP 85201 around Dec 25, about 42 days before the Feb 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 85201 planting calendar

When to plant tomatoes in Mesa, AZ - Zone 10a

Q: When is the first frost in Mesa?

Mesa (ZIP 85201) has an average first fall frost around Dec 15, leaving about 313 frost-free days.

In ZIP 85201, plant tomatoes around Feb 12; this uses the Phoenix frost station, USDA zone 10a, and tomatoes timing rules.

Your Phoenix calendar has a 313-day estimated frost-free season. This estimate uses the representative Phoenix frost station, USDA zone 10a, and tomatoes timing rules.

Source: phoenix-skyharbor frost station, USDA zone 10a, 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 10a Phoenix frost station University of Arizona Extension Updated 2026-06-28

Read the method

Answer first

When to start tomatoes seeds indoors in Mesa

In ZIP 85201, start tomatoes seeds indoors around Dec 25, about 42 days before the Feb 5 last-frost estimate.

Start tomatoes seeds indoors in Mesa around Dec 25, about 42 days before the Feb 5 last-frost estimate.

Seed starting schedule

Tomatoes dates for Mesa, AZ

Step	Date	How to use it
Start Indoors	December 25, 2025	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	February 12, 2026	Move hardened-off seedlings outside after the frost-risk window.

Last frost

When is the last frost in Mesa?

Mesa (ZIP 85201) has an average last spring frost around Feb 5.

First frost

When is the first frost in Mesa?

The average first fall frost is around Dec 15, giving about 313 frost-free days.

Season map

Tomatoes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Dec 25

Transplant

Feb 12

Harvest

May 1

Frost watch

Sep 28

Reminder workflow

Every date has a next action

Start tomatoes indoorsDec 25

Last frost windowFeb 5

Transplant tomatoesFeb 12

First tomatoes harvest windowMay 1

Last tomatoes sowing targetSep 28

Signal	Value	Why it matters
Last frost estimate	February 5, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	December 15, 2026	Fall planting counts backward from this date.
Season length	313 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

Phoenix frost history and USDA zone 10a shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

University of Arizona 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 Dec 15. A conservative last sowing target is around Sep 28.