Conditional — Some Areas
orchid tree (zones 9-11) reaches only part of Alaska (1a-9a): zone 9 are in range, so where you are in the state decides it.
One zone short — what would close it
Orchid Tree is hardy to zone 9, and the warmest ground in Alaska is zone 8 — 1 zone short. Planted in open ground it will not survive a Alaska winter. To grow it here, grow orchid tree in a container and move it under cover for the coldest weeks, or give it a greenhouse.
Season extension and overwintering under cover both work at this margin. How to buy the weeks →
Zone math from 9-11 (plant) against 1-8 (Alaska). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
Your yard isn't the whole zone.
Alaska spans zones 1a-9a, 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 orchid tree against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Orchid Tree Needs
- USDA Zones: 9-11
- Sun: Full Sun
Alaska Has
- USDA Zones: 1a-9a
- Last Hard Freeze (28°F): Apr 16 - May 15
- First Hard Freeze (28°F): Sep 24 - Oct 29
- Annual Rainfall: 10-160 inches
- Common Soils: Permafrost, Glacial silt, Volcanic ash
Plant Zone Range (zones 9-11)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Orchid Tree in Alaska
The frost window
Across Alaska, the last spring hard freeze (28°F) clears between Apr 16 and May 15, and the first fall hard freeze lands between Sep 24 and Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 132-day window you can count on — up to 196 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
Alaska runs as cold as USDA zone 1, and no sourced winter-hardiness floor is on record for orchid tree, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether orchid tree is a permanent planting or a replant-every-spring crop for you turns on your own zone within Alaska; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — North Slope County, not the statewide average.
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.
Soil + Drainage Fit
Orchid Tree likes near-neutral soil (pH 5-7.5). That's the common-ground band across Alaska's permafrost and glacial silt — 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 Alaska soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Alaska site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 16.6% of Alaska as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Orchid Tree sits mid-range for drought tolerance, so either extreme can cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Alaska soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Orchid Tree in Alaska — Quick Answer
- Verdict: Conditional — Some Areas
- Plant Zones: 9-11 (USDA PLANTS Database)
- State Zones: 1a-9a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 16 - May 15 to Sep 24 - Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Orchid Tree in Alaska
Zone compatibility tells you about winter cold survival — but Alaska growers also need to think about:
Extremely short growing season (70-110 frost-free days)
Permafrost prevents deep root growth in many areas
Limited soil development in glacial terrain
Growing orchid tree here specifically
Orchid Tree likes pH 5.0–7.5 and takes cold to about 41°F, yet neither saves it from wet feet — SSURGO maps about 16.6% of Alaska poorly-drained, where its crown sit and rot.
Set orchid tree high on bermed, grit-amended ground so winter and storm water drain away from the crown. How to handle it →
What to actually do about these — and the constraints that apply to every Alaska grower, not just orchid tree — is covered on the Alaska growing guide.
Timing shifts within Alaska
Alaska isn't one climate. In North Slope County, the last hard freeze (28°F) holds until about Jun 7 — roughly 33 days later than the recorded state median — so plant orchid tree to your county's window, not the statewide date.
County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). A parcel report resolves your address's own frost dates.
Where in Alaska Orchid Tree Is Zone-Hardy
Orchid Tree is rated for USDA zones 9–11. No Alaska county reaches it. Even Yukon-Koyukuk County, the state’s mildest winter at zone 3a-4b, sits below the plant’s zone 9 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
Across those 30 counties Alaska’s winter-low ladder runs from zone 3a-4b in Aleutians East County to zone 3a-4b in Yukon-Koyukuk County — 1.5 USDA zones of spread, which is 15°F between the two counties’ average coldest night of the year. None of that range reaches the band orchid tree needs, so here the statewide answer really is the answer.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. Orchid Tree’s zone 9–11 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Orchid Tree draws honeybees, native bees, and butterflies (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, orchid tree can only work that bloom inside Alaska's frost window — roughly 147 days, opening after the last 28°F freeze (Apr 16 - May 15) and closing at the first (Sep 24 - Oct 29), per NOAA Regional Climate Centers ACIS station record, 1991-2020.
Alaska Cooperative Extension
For Alaska-specific cultivar recommendations, planting calendars, and pest pressure for orchid tree, the canonical source is UAF Cooperative Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Orchid Tree native to Alaska?
No — the USDA PLANTS Database lists Orchid Tree as introduced rather than native in the Lower 48, so it is not part of Alaska's native flora. It grows here as a garden plant; pairing it with a few Alaska natives keeps local pollinators fed too.
Looking for plants that belong here? The Alaska growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Orchid Tree in Alaska
When can I plant Orchid Tree in Alaska?
Alaska's last spring hard freeze (28°F) clears between Apr 16 and May 15, and the first fall hard freeze lands between Sep 24 and Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Orchid Tree, so this page does not state whether it overwinters in Alaska 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 Orchid Tree grown in across Alaska?
Alaska spans USDA hardiness zones 1a-9a (USDA ARS PHZM 2023). Orchid Tree 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 Alaska site have?
A typical Alaska site sees ~147 frost-free days per year (derived from NOAA Regional Climate Centers ACIS station record, 1991-2020). Orchid Tree 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. In cooler counties like North Slope, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Orchid Tree native to Alaska?
No — the USDA PLANTS Database lists Orchid Tree as introduced rather than native in the Lower 48, so it is not part of Alaska's native flora. It grows here as a garden plant; pairing it with a few Alaska natives keeps local pollinators fed too.
How should I amend the soil for Orchid Tree in Alaska?
Orchid Tree prefers pH 5-7.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Alaska soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Orchid Tree actually grow on my specific land in Alaska?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores orchid tree 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 Alaska
State-level data is a sketch. Your Growable Ground report scores orchid tree against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Alaska orchid tree averages can't show:
We read public map data around Alaska — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Alaska orchid tree average
Explore More
Growing guides for orchid tree
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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