Unlikely — Zone Mismatch
kapok (zones 11-12) does not overlap with Utah's zone range (4a-9a). Growing outdoors is unlikely without significant protection.
One zone short — what would close it
Kapok is hardy to zone 11, and the warmest ground in Utah is zone 9 — 1 zone short. Planted in open ground it will not survive a Utah winter. To grow it here, grow kapok 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 11-12 (plant) against 4-9 (Utah). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['hoop_house'] (+1.5 zones) via api/fast_sections.py Unlock Engine v2.
Kapok in Utah — the short answer
Kapok in Utah: hardy in zones 11–12, full sun.
- Plant zones
- 11-12
- Hardy to zone 10b: Tropical Plants Database (Useful Tropical Plants) lists -1 °C, converted to zone 10b, checked Oct 2026. The source rates it slightly hardier than our range. Ceiling: our plant database.
- Utah zones
- 4a-9a
- USDA PHZM 2023
- Frost window
- Apr 12 - May 6 – Oct 8 - Oct 27
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 98 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.
Utah spans zones 4a-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 kapok 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 parcel report in seconds — read in full free for your first 14 days
Utah is not one climate
Utah’s winter-low ladder runs across 29 counties, from zone 4.5 in Rich County to zone 7.5 in Washington County. That is 30°F between the two counties’ average coldest night — the difference between kapok overwintering in the ground and coming under cover.
The middle half of 29 counties runs 6–7 zones, with a median of 6.5 zones — a 3-zone span end to end.
Measured across 29 Utah 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 Kapok Stands in Utah
Kapok is rated for zones 11–12 — a cold floor USDA puts at 40 to 50°F. No Utah 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 Utah winters, not about kapok.
Below the zone 11 floor
29 counties
- Rich County · zone 4b
- Daggett County · zone 5b
- Iron County · zone 5b
3 of 29 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
Kapok Needs
- USDA Zones: 11-12
- Sun: Full Sun
- Mature size: 150 ft tall
- Drought tolerance: Low
Utah Has
- USDA Zones: 4a-9a
- Last Hard Freeze (28°F): Apr 12 - May 6
- First Hard Freeze (28°F): Oct 8 - Oct 27
- Annual Rainfall: 5-20 inches
- Common Soils: Sandy loam, Alkaline clay, Desert sand
Plant Zone Range (zones 11-12)
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 Kapok in Utah
The frost window
Across Utah, the last spring hard freeze (28°F) clears between Apr 12 and May 6, and the first fall hard freeze lands between Oct 8 and Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 155-day window you can count on — up to 198 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
Utah runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for kapok, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether kapok is a permanent planting or a replant-every-spring crop for you turns on your own zone within Utah; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Summit 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.
Soil + Drainage Fit
Kapok likes near-neutral soil (pH 5-7.5). That's the common-ground band across Utah's sandy loam and alkaline clay — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 5.5 and 6.5 — worth knowing before you decide whether a Utah soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Utah site is heavier clay or sits in a low spot, a raised bed lifts the roots above wet ground, or work in compost.
Your land, not the state average
Utah's soils run mostly loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Kapok 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 kapok 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. Utah soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant kapok for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before kapok goes in. What follows is Utah’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Utah — and how to grow with it.
We checked the federal record across Utah — 11,221 documented sites across 7 of the 8 source types we track.
The most significant on record: 202 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Utah carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds of imported, lab-tested soil grow well almost anywhere in the meantime.
Sources Checked
across Utah
Severity Distribution
across Utah
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Utah, Mining runs higher than the national average — 3,654 sites across Utah. That's not a problem with your land — it's information about it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Sources: EPA, USGS — 950K documented sites tracked nationwide across 8 federal source types.
What Else to Consider for Kapok in Utah
Zone compatibility tells you about winter cold survival — but Utah growers also need to think about:
Very low rainfall — irrigation essential
Alkaline soils (pH 7.5-8.5) limit many species
High altitude frost risk in mountain valleys
Growing kapok here specifically
Kapok sends deep roots and rates to zones 11–12, but much of Utah sits on slow-draining, restrictive ground (SSURGO hydrologic group D) that forks and stunts them.
Loosen a deep, stone-free bed for kapok and break any compacted or hardpan layer before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Utah grower, not just kapok — is covered on the Utah growing guide.
Timing shifts within Utah
Utah isn't one climate. In Summit County, the last hard freeze (28°F) holds until about Jun 10 — roughly 45 days later than the recorded state median — so plant kapok 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 Utah Kapok Is Zone-Hardy
Kapok is rated for USDA zones 11–12. No Utah county reaches it. Even Washington County, the state’s mildest winter at zone 7b, sits below the plant’s zone 11 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
Across those 29 counties Utah’s winter-low ladder runs from zone 4b in Rich County to zone 7b in Washington County — 3 USDA zones of spread, which is 30°F between the two counties’ average coldest night of the year. None of that range reaches the band kapok needs, so here the statewide answer really is the answer.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. Kapok’s zone 11–12 band: Hardy to zone 10b: Tropical Plants Database (Useful Tropical Plants) lists -1 °C, converted to zone 10b, checked Oct 2026. The source rates it slightly hardier than our range. Ceiling: our plant database.. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Kapok draws moths (moderate value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, kapok can only work that bloom inside Utah's frost window — roughly 175 days, opening after the last 28°F freeze (Apr 12 - May 6) and closing at the first (Oct 8 - Oct 27), per NOAA Regional Climate Centers ACIS, 1991-2020. Pollinator value: We haven't confirmed this against a published source yet.
Utah Cooperative Extension
For Utah-specific cultivar recommendations, planting calendars, and pest pressure for kapok, the canonical source is Utah State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Kapok in Utah
When can I plant Kapok in Utah?
Utah's last spring hard freeze (28°F) clears between Apr 12 and May 6, and the first fall hard freeze lands between Oct 8 and Oct 27 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Kapok, so this page does not state whether it overwinters in Utah 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 Kapok grown in across Utah?
Utah spans USDA hardiness zones 4a-9a (USDA ARS PHZM 2023). Kapok is listed for zones 11-12, which do not overlap them, so there is no zone in Utah where this page can call outdoor growing reliable. A parcel report resolves your own address's zone.
How many frost-free days does a typical Utah site have?
A typical Utah site sees ~175 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Kapok needs 270+ 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 Summit, the freeze-free season runs shorter than the state average, so verify your own county's window.
How should I amend the soil for Kapok in Utah?
Kapok prefers pH 5-7.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Utah soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Kapok actually grow on my specific land in Utah?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores kapok against your address's mapped soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Utah
State-level data is a sketch. Your Growable Ground report scores kapok against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Utah kapok averages can't show:
We read public map data around Utah — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Utah kapok average
Explore More
Growing guides for kapok
Explore Utah county by county
Utah carries 29 counties with their own USDA zone — a sample of the growing pages for kapok there:
Where else kapok grows
Kapok's zone band crosses state lines — these are the states closest to Utah 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 Utah
Utah has a growing page for 1,033 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
Last updated: