Yes — Strong Match
skirret (zones 5-9) fits entirely within Washington's zone range (4a-9a).
Your yard isn't the whole zone.
Washington spans zones 4a-9a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score skirret against your land's actual soil, sun, and frost.
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Zone Comparison
Skirret Needs
- USDA Zones: 5-9
- Soil pH: 5.5 - 7.5
- Sun: Part Sun
- Drainage: poorly (saturated >50% of year), well (dry spells)
- Frost-Free Days: 40+
Washington Has
- USDA Zones: 4a-9a
- Last Frost: Mar 1 - Jun 1
- First Frost: Sep 15 - Nov 15
- Annual Rainfall: 6-90 inches
- Common Soils: Volcanic ash, Silt loam (Palouse), Sandy loam
Plant Zone Range (zones 5-9)
Preferred Soil pH
Plant data: USDA PLANTS Database / plant_species_v5.csv. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Skirret in Washington
The frost window
Across Washington, the last spring frost clears between Mar 1 and Jun 1, and the first fall frost lands between Sep 15 and Nov 15 (NOAA Climate Normals 1991-2020). Counting from the latest last frost to the earliest first frost, that's a 106-day window you can count on — up to 259 days on a mild site in a kind year.
Frost tenderness
Skirret is frost-tender — its listed minimum temperature is 41°F (USDA PLANTS Database) — so set plants out after the last frost has cleared your local site, not the state's earliest date.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
Zone compatibility says you can survive winter here. Whether the growing season is long enough — and warm enough — is a different question.
Frost-free days
Skirret wants 40+ frost-free days; a typical Washington site sees ~130 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Climate aggregates derive from USDA NRCS county-level hardiness data + Cornell CALS Extension GDD-by-region tables + MSU Extension chill-hours-by-zone (1991-2020 NOAA Climate Normals baseline).
Soil + Drainage Fit
Skirret likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Washington's volcanic ash and silt loam (palouse) — a soil test confirms it for your site. Drainage matters: this plant wants poorly (saturated >50% of year), well (dry spells). If your Washington site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. Washington soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Skirret in Washington — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: 5-9 (USDA PLANTS Database)
- State Zones: 4a-9a (USDA ARS PHZM 2023)
- Growing Season: Mar 1 - Jun 1 to Sep 15 - Nov 15 (NOAA Climate Normals)
What Else to Consider
Zone compatibility tells you about winter cold survival — but Washington growers also need to think about:
Extreme rain divide: 90+ inches west, 6 inches east of Cascades
Plant to your side of the Cascades, not to the state — your exact spot's rainfall decides the whole plan.
East side requires irrigation — no rain from June through September
With no summer rain, drip lines and deep mulch are the growing season — set them up before June.
Slug and root rot pressure on the wet west side
Raise the beds, bait the slugs, and water mornings only — the wet-side trio that keeps roots and leaves healthy; extension has the details.
Short seasons at elevation in the Cascades and northeast corners
In the short-season corners, fast varieties plus a cold frame or tunnel reliably close the gap.
Pollinator + Wildlife Value
Skirret draws pollinators (moderate value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops.
Washington Cooperative Extension
For Washington-specific cultivar recommendations, planting calendars, and pest pressure for skirret, the canonical source is WSU Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Skirret in Washington
When can I plant Skirret in Washington?
Washington's last spring frost clears between Mar 1 and Jun 1, and the first fall frost lands between Sep 15 and Nov 15 (NOAA Climate Normals 1991-2020). Skirret is frost-tender — its listed minimum temperature is 41°F (USDA PLANTS Database) — so wait until the last frost has cleared your specific site before planting out.
What hardiness zone is Skirret grown in across Washington?
Washington spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Skirret carries a range of zones 5-9, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Washington site have?
A typical Washington site sees ~130 frost-free days per year (derived from NOAA Climate Normals 1991-2020). Skirret needs 40+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
How should I amend the soil for Skirret in Washington?
Skirret prefers pH 5.5-7.5 and poorly (saturated >50% of year), well (dry spells) drainage (USDA PLANTS Database). That sits in the common-ground band across Washington soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Skirret actually grow on my specific land in Washington?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores skirret against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Washington
State-level data is a sketch. Your Growable Ground report scores skirret against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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