Unlikely — Zone Mismatch
neem (zones 10-12) does not overlap with Washington's zone range (4a-9b). Growing outdoors is unlikely without significant protection.
One zone short — what would close it
Neem is hardy to zone 10, and the warmest ground in Washington is zone 9 — 1 zone short. Planted in open ground it will not survive a Washington winter. To grow it here, grow neem in a hoop house or unheated greenhouse — its modeled 1.5-zone lift covers this gap.
A hoop house or unheated greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 10-12 (plant) against 5-9 (Washington). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['hoop_house'] (+1.5 zones) via api/fast_sections.py Unlock Engine v2.
Neem in Washington — the short answer
Neem in Washington: hardy in zones 10–12, full sun, against a state median of ~208 frost-free days.
- Plant zones
- 10-12
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Washington zones
- 4a-9b
- USDA PHZM 2023
- Frost window
- Mar 16 - Apr 15 – Oct 24 - Nov 18
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 131 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Washington spans zones 4a-9b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score neem against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Washington is not one climate
Washington’s winter-low ladder runs across 39 counties, from zone 6 in Ferry County to zone 9 in San Juan County. That is 30°F between the two counties’ average coldest night — the difference between neem overwintering in the ground and coming under cover.
The middle half of 39 counties runs 7–8.5 zones, with a median of 7 zones — a 3-zone span end to end.
Measured across 39 Washington counties. USDA PHZM 2023, per county. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where Neem Stands in Washington
Neem is rated for zones 10–12 — a cold floor USDA puts at 30 to 40°F. No Washington county sits inside it, so in open ground this is a grown-under-cover plant here rather than a bed plant — which is a statement about Washington winters, not about neem.
Below the zone 10 floor
39 counties
- Ferry County · zone 6a
- Okanogan County · zone 6a
- Pend Oreille County · zone 6a
3 of 39 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Zone Comparison
Neem Needs
- USDA Zones: 10-12
- Frost-Free Days: 150+
- Sun: Full Sun
- Mature size: 65 ft tall
- Drought tolerance: High
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 10-12)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Neem 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.
Winter standing
Washington runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for neem, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether neem is a permanent planting or a replant-every-spring crop for you turns on your own zone within Washington; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Whatcom County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. 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 neem does not survive a Washington winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on Washington under protection.
Frost-free days
Neem wants 150+ frost-free days; a typical Washington site sees ~208 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Chill hours
Neem has no winter-chill requirement — its listed minimum is 0 hours (Growable Ground Plant Database). Washington typically banks ~2500 chill hours per winter (from PRISM 1991-2020 climate normals), so chill is not a constraint on this plant here — and not evidence in its favour either. Winter survival and season length are what decide it.
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.
Soil + Drainage Fit
Neem likes near-neutral soil (pH 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. It will grow across that whole span, but it does best between pH 5.5 and 7 — worth knowing before you decide whether a Washington soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Washington site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Washington's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Neem needs about 59 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how neem performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Washington soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Neem 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
Growing neem here specifically
Neem needs pH 5.0–7.5; Washington's dominant silt loam soils may or may not deliver that, so your parcel's SSURGO map unit is the real test.
Start with a soil test on your own ground and adjust pH and texture to fit neem's 5.0–7.5 range. How to handle it →
What to actually do about these — and the constraints that apply to every Washington grower, not just neem — is covered on the Washington growing guide.
Timing shifts within Washington
Washington isn't one climate. In Whatcom County, the last hard freeze (28°F) holds until about May 29 — roughly 54 days later than the recorded state median — so plant neem to your county's window, not the statewide date.
Neem needs about 150 days of frost-free season to complete its cycle. 38 of Washington’s 39 counties give it that outright. The tightest that does is Chelan County at 158 frost-free days — 8 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, leaving neem about 58 days of slack on a typical parcel — room for a second sowing where the season runs long.
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"). Neem's 150-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Neem draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, neem 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.
Good to Know Before You Plant Neem
Neem is listed as toxic to dogs, cats (all) at a moderate level (Pet Poison Helpline). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Washington Cooperative Extension
For Washington-specific cultivar recommendations, planting calendars, and pest pressure for neem, 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 Neem in Washington
When can I plant Neem 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). No sourced winter-hardiness floor is on record for Neem, so this page does not state whether it overwinters in Washington and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Neem grown in across Washington?
Washington spans USDA hardiness zones 4a-9b (USDA ARS PHZM 2023). Neem carries a range of zones 10-12, 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). Neem needs 150+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Whatcom, the freeze-free season runs shorter than the state average, so verify your own county's window.
How should I amend the soil for Neem in Washington?
Neem prefers pH 5-7.5 and well (dry spells) drainage (FAO ECOCROP). 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 Neem actually grow on my specific land in Washington?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores neem 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 neem against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Washington neem averages can't show:
We read public map data around Washington — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Washington neem average
Explore More
Growing guides for neem
Explore Washington county by county
Washington carries 39 counties with their own USDA zone — a sample of the growing pages for neem there:
Where else neem grows
Neem's zone band crosses state lines — these are the states closest to Washington in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Washington
Washington has a growing page for 1,038 plants — a rotating sample of the rest of the shelf.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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