When to plant tarragon in Seattle, Washington

March 13 – March 27

Transplant outdoors · typical Seattle year

Climate basis: NOAA station Seattle Boeing Fld, WA (USW00024234), 5 mi (8 km) from downtown Seattle (ZCTA 98104 centroid), elevation 20 ft, on the 1991–2020 climate normals. Transplant tarragon outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (March 13). One year in ten still freezes after April 1.

Last spring freezeMarch 131-in-10 after Apr 1

First fall freezeNovember 171-in-10 before Nov 1

Frost-free season≈ 247 daysmedian at 32°F

Hard freeze, 28°Feb 18 – Dec 2kills even hardy greens

USDA zone9a20 to 25°F winter low — not frost timing

The Seattle year

Transplant outdoorsMar 13 – Mar 27

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 1

Tarragon in Seattle · freeze context from Seattle Boeing Fld, WA, 1991–2020 normals.

Every method, with its sources

Transplant outdoors

Mar 13 – Mar 27

USU Extension says to transplant French tarragon in the spring after the last frost so the tender young shoots survive, a point rule that opens a two-week planting span at the last spring freeze. Anchored to the median last spring freeze (Mar 13). Utah State University Extension · Virginia Cooperative Extension, Virginia Tech

Start seeds indoors

Not calculated

The cited extension guides do not time an indoor seed-starting window for this crop.

Direct-sow outdoors

Not calculated

The cited extension guides do not time direct sowing for this crop.

Fall planting

Not calculated

No source-backed fall planting rule exists for this crop in the registry, so no fall window is calculated.

Variety assumption: Assumes French tarragon, which Virginia Cooperative Extension says can only be propagated asexually — seed-grown plants are the flavourless Russian type — so no seed-sowing window is given.

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (2)

Utah State University Extension: How to Grow French Tarragon in Your Garden (accessed 2026-07-25)
"Transplant French tarragon in the spring, after the last frost, to ensure the survival of tender young shoots."
Virginia Cooperative Extension, Virginia Tech: Herb Culture and Use (Publication 426-420) (accessed 2026-07-25)
"In addition, many culinary herbs, such as tarragon, can only be propagated asexually; seed-grown plants lack the oils that give them flavor."

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