When should I plant tomatoes in ZIP 97204?

In ZIP 97204, the main tomatoes target is around Apr 8, based on the representative Portland frost station and USDA zone 9a.

When should I start tomatoes seeds indoors in 97204?

Start tomatoes seeds indoors in ZIP 97204 around Feb 18, about 42 days before the Apr 1 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 97204 planting calendar

When to plant tomatoes in Portland, OR - Zone 9a

Q: When is the first frost in Portland?

Portland (ZIP 97204) has an average first fall frost around Nov 10, leaving about 223 frost-free days.

In ZIP 97204, plant tomatoes around Apr 8; this uses the Portland frost station, USDA zone 9a, and tomatoes timing rules.

Your Portland calendar has a 223-day estimated frost-free season. This estimate uses the representative Portland frost station, USDA zone 9a, and tomatoes timing rules.

Source: portland-intl frost station, USDA zone 9a, 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 9a Portland frost station Oregon State University Extension Updated 2026-06-28

Read the method

Answer first

When to start tomatoes seeds indoors in Portland

In ZIP 97204, start tomatoes seeds indoors around Feb 18, about 42 days before the Apr 1 last-frost estimate.

Start tomatoes seeds indoors in Portland around Feb 18, about 42 days before the Apr 1 last-frost estimate.

Seed starting schedule

Tomatoes dates for Portland, OR

Step	Date	How to use it
Start Indoors	February 18, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	April 8, 2026	Move hardened-off seedlings outside after the frost-risk window.

Last frost

When is the last frost in Portland?

Portland (ZIP 97204) has an average last spring frost around Apr 1.

First frost

When is the first frost in Portland?

The average first fall frost is around Nov 10, giving about 223 frost-free days.

Season map

Tomatoes windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Feb 18

Transplant

Apr 8

Harvest

Jun 25

Frost watch

Aug 24

Reminder workflow

Every date has a next action

Start tomatoes indoorsFeb 18

Last frost windowApr 1

Transplant tomatoesApr 8

First tomatoes harvest windowJun 25

Last tomatoes sowing targetAug 24

Signal	Value	Why it matters
Last frost estimate	April 1, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	November 10, 2026	Fall planting counts backward from this date.
Season length	223 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

Portland frost history and USDA zone 9a shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Oregon 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 Nov 10. A conservative last sowing target is around Aug 24.