Conditional — Some Areas
plantain (zones 9-11) reaches only part of Washington (4a-9b): zone 9 are in range, so where you are in the state decides it.
Your yard isn't the whole zone.
Washington spans zones 4a-9b, 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 plantain against your land's actual soil, sun, and frost.
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Zone Comparison
Plantain Needs
- USDA Zones: 9-11
- Mature size: 15 ft tall
- Drought tolerance: Low
Washington Has
- USDA Zones: 4a-9b
- Last Hard Freeze (28°F): Mar 16 - Apr 15
- First Hard Freeze (28°F): Oct 24 - Nov 18
- Annual Rainfall: 6-90 inches
- Common Soils: Volcanic ash, Silt loam (Palouse), Sandy loam
Plant Zone Range (zones 9-11)
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Plantain in Washington
The frost window
Across Washington, the last spring hard freeze (28°F) clears between Mar 16 and Apr 15, and the first fall hard freeze lands between Oct 24 and Nov 18 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 192-day window you can count on — up to 247 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
Days to maturity vs. the window
At 300 days to maturity (USDA PLANTS Database), even Washington's kindest 247-day season runs short — challenging without season extension. An indoor start plus row cover on both shoulders of the season closes the gap.
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
The zone check says plantain survives winter in part of Washington, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Plantain matures in ~300 days (Growable Ground Plant Database). A typical Washington site has ~208 frost-free days, so tight — start indoors or use season-extension to close the gap.
Growing degree days
Plantain needs ~5000 GDD (base 50°F) to ripen. The state median runs ~1740 GDD (from PRISM 1991-2020 climate normals), so Washington's typical season runs short on heat — pick a south-facing site and consider season extension.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Plantain in Washington — Quick Answer
- Verdict: Conditional — Some Areas
- Plant Zones: 9-11 (USDA PLANTS Database)
- State Zones: 4a-9b (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Mar 16 - Apr 15 to Oct 24 - Nov 18 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 300 days
What Else to Consider for Plantain in Washington
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
East side requires irrigation — no rain from June through September
Slug and root rot pressure on the wet west side
Short seasons at elevation in the Cascades and northeast corners
What to actually do about these — and the constraints that apply to every Washington grower, not just plantain — is covered on the Washington growing guide.
Timing shifts within Washington
Plantain needs about 300 days of frost-free season from planting to harvest. 1 of Washington’s 39 counties give it that outright. The tightest that does is San Juan County at 300 frost-free days — 0 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Washington’s 39 counties the frost-free season runs from 131 days in Whatcom County to 300 days in San Juan County — a spread of 169 days, which is why a single statewide planting date misleads. The median Washington county sees 208 frost-free days, which is 92 days short of what plantain needs — so on a typical Washington parcel this is a transplant-or-protect crop, not a direct-sow one.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Plantain's 300-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Where in Washington Fits Best
Even within Washington's zones 4a-9b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for plantain (USDA PHZM 2023):
Pollinator + Wildlife Value
Plantain draws hummingbirds (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, plantain can only work that bloom inside Washington's frost window — roughly 208 days, opening after the last 28°F freeze (Mar 16 - Apr 15) and closing at the first (Oct 24 - Nov 18), per NOAA Regional Climate Centers ACIS, 1991-2020.
Washington Cooperative Extension
For Washington-specific cultivar recommendations, planting calendars, and pest pressure for plantain, 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 Plantain in Washington
When can I plant Plantain in Washington?
Washington's last spring hard freeze (28°F) clears between Mar 16 and Apr 15, and the first fall hard freeze lands between Oct 24 and Nov 18 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
Can Plantain mature before first frost in Washington?
Plantain needs 300 days to mature (USDA PLANTS Database), and even Washington's longest typical season runs 247 days (NOAA Regional Climate Centers ACIS, 1991-2020) — challenging without season extension. An indoor start plus row cover on both season shoulders closes the gap.
What hardiness zone is Plantain grown in across Washington?
Washington spans USDA hardiness zones 4a-9b (USDA ARS PHZM 2023). Plantain carries a range of zones 9-11, 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 ~208 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Plantain should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Will Plantain actually grow on my specific land in Washington?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores plantain 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 plantain against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Washington plantain averages can't show:
We read public map data around Washington — soil, climate, flood, and parcel records. How we handle your address.
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