GrowZone

ZIP 98101 · Seattle, WA · USDA zone 9a

In ZIP 98101, plant tomatoes around Mar 27.

Your Seattle calendar has a 245-day estimated frost-free season. This estimate uses the representative Seattle frost station, USDA zone 9a, and tomatoes timing rules.

Read the method
Start tomatoes indoorsFeb 6
Last frost windowMar 20
Transplant tomatoesMar 27
First tomatoes harvest windowJun 13
Last tomatoes sowing targetSep 3
SignalValueWhy it matters
Last frost estimateMarch 20, 2026Warm-season transplant risk starts falling after this window.
First frost estimateNovember 20, 2026Fall planting counts backward from this date.
Season length245 daysLonger seasons can support succession crops.
Spacing18-24 inAirflow and root space affect yield.
Soil temperature60 F+Seeds and transplants stall in cold soil.

GrowZone may earn from qualifying seed or supply links when real affiliate IDs are configured. No monetized links are active without disclosure.

Local data

Why this date changes by ZIP

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

Washington 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 20. A conservative last sowing target is around Sep 3.