When to plant potatoes in Spokane, Washington

March 15 – March 29

Direct-sow outdoors · typical Spokane year

Climate basis: NOAA station Spokane INTL AP, WA (USW00024157), 5 mi (8 km) from downtown Spokane (ZCTA 99201 centroid), elevation 2353 ft, on the 1991–2020 climate normals. Plant seed potatoes from approximately the dates above, anchored to the median last spring 32°F freeze (April 26). One year in ten still freezes after May 10.

Last spring freezeApril 261-in-10 after May 10

First fall freezeOctober 121-in-10 before Sep 29

Frost-free season≈ 168 daysmedian at 32°F

Hard freeze, 28°Apr 6 – Oct 23kills even hardy greens

USDA zone7a0 to 5°F winter low — not frost timing

The Spokane year

Direct-sow outdoorsMar 15 – Mar 29

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

Potatoes in Spokane · freeze context from Spokane INTL AP, WA, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Mar 15 – Mar 29

Purdue: hardy — plant seed pieces 4–6 weeks before the last spring frost. Minnesota adds the practical caveat: plant as soon as the soil warms. Anchored to the median last spring freeze (Apr 26). Purdue University Extension · University of Minnesota Extension

Start seeds indoors

Not calculated

Potatoes are grown from seed pieces, not indoor-started seedlings.

Transplant outdoors

Not calculated

The cited extension guides do not time an outdoor transplanting window 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 a mid-season variety (about 90–110 days from planting).

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)

Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.
University of Minnesota Extension: Growing potatoes (accessed 2026-07-24)
"Plant seed pieces as soon as the soil warms" — soil-temperature caveat to the frost-relative rule.

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