When to plant hairy vetch in Seattle, Washington
October 3 – November 2
Fall planting · typical Seattle yearClimate 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. Plant hairy vetch for fall from approximately the dates above, anchored to the median first fall 32°F freeze (November 17). One year in ten still freezes after April 1.
The Seattle year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Apr 1
Every method, with its sources
Fall planting
Oct 3 – Nov 2Alabama Extension states an explicit frost-anchored range — plant hairy vetch 15 to 45 days before the killing frost — which encodes directly as 45 to 15 days ahead of the first fall freeze; UMass Extension's general cover-crop rule of about 30 days before the first expected frost falls inside that range, so the wider Alabama interval is used and no conflict needed resolving. Anchored to the median first fall freeze (Nov 17). Alabama Cooperative Extension System · UMass Amherst Center for Agriculture, Food, and the Environment
Start seeds indoors
Not calculatedThe cited extension guides do not time an indoor seed-starting window for this crop.
Transplant outdoors
Not calculatedThe cited extension guides do not time an outdoor transplanting window for this crop.
Direct-sow outdoors
Not calculatedThe cited extension guides do not time direct sowing for this crop.
Variety assumption: Assumes seeding for overwintering and spring nitrogen, commonly drilled or broadcast in a mix with winter rye.
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.
Crop rule sources (2)
- Alabama Cooperative Extension System: Cover Crops: Legumes (accessed 2026-07-25)"Plant hairy vetch 15 to 45 days before the killing frost."
- UMass Amherst Center for Agriculture, Food, and the Environment: Cover Crops — growing tips (accessed 2026-07-25)"As a general rule, cover crops should be planted about 30 days before the first expected frost date."