When to plant horseradish in Seattle, Washington
January 30 – February 13
Transplant outdoors · 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. Transplant horseradish 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.
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
Transplant outdoors
Jan 30 – Feb 13Purdue Extension HO-186-W Table 1 places horseradish in the group headed "Hardy (tolerates hard frost) plant 4-6 weeks before last spring frost," and footnotes it as typically vegetatively propagated, so the six-to-four-week pre-frost window is applied to setting out root cuttings rather than to seed; no other extension source located gives a frost-anchored horseradish planting date, so there was nothing to reconcile against. Anchored to the median last spring freeze (Mar 13). Purdue University Extension, Department of Horticulture and Landscape Architecture
Start seeds indoors
Not calculatedThe cited extension guides do not time an indoor seed-starting window for this crop.
Direct-sow outdoors
Not calculatedThe cited extension guides do not time direct sowing for this crop.
Fall planting
Not calculatedNo source-backed fall planting rule exists for this crop in the registry, so no fall window is calculated.
Variety assumption: Assumes planting purchased root cuttings or sets of a standard variety such as Common or Bohemian, lifted the following fall after frost.
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 (1)
- Purdue University Extension, Department of Horticulture and Landscape Architecture: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-25)"Table 2. Cool season plants for late-summer or fall planting (plant at least 4-8* weeks before first fall frost) (See Figure 2)"