Conditional — Some Areas
annatto (zones 10-12) reaches only part of Arizona (5b-10b): zone 10 are in range, so where you are in the state decides it.
Annatto in Arizona — the short answer
Annatto in Arizona: hardy in zones 10–12, full sun, against a state median of ~266 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
- Arizona zones
- 5b-10b
- USDA PHZM 2023
- Frost window
- Feb 1 - Apr 2 – Nov 13 - Dec 12
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 150 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.
Arizona spans zones 5b-10b, 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 annatto 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.
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Arizona is not one climate
Arizona’s winter-low ladder runs across 15 counties, from zone 6 in Coconino County to zone 9.5 in Yuma County. That is 35°F between the two counties’ average coldest night — the difference between annatto overwintering in the ground and coming under cover.
The middle half of 15 counties runs 7.5–9.5 zones, with a median of 8.5 zones — a 3.5-zone span end to end.
Measured across 15 Arizona 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 Annatto Stands in Arizona
Annatto is rated for zones 10–12 — a cold floor USDA puts at 30 to 40°F. No Arizona 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 Arizona winters, not about annatto.
Below the zone 10 floor
15 counties
- Coconino County · zone 6a
- Apache County · zone 6b
- Navajo County · zone 7a
3 of 15 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
Annatto Needs
- USDA Zones: 10-12
- Frost-Free Days: 150+
- Sun: Full Sun
Arizona Has
- USDA Zones: 5b-10b
- Last Hard Freeze (28°F): Feb 1 - Apr 2
- First Hard Freeze (28°F): Nov 13 - Dec 12
- Annual Rainfall: 3-25 inches
- Common Soils: Caliche, Sandy loam, Desert pavement
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 Annatto in Arizona
The frost window
Across Arizona, the last spring hard freeze (28°F) clears between Feb 1 and Apr 2, and the first fall hard freeze lands between Nov 13 and Dec 12 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 225-day window you can count on — up to 314 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
Arizona runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for annatto, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether annatto is a permanent planting or a replant-every-spring crop for you turns on your own zone within Arizona; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Coconino 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 annatto survives winter in part of Arizona, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Annatto wants 150+ frost-free days; a typical Arizona site sees ~266 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
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
Annatto tolerates a wide pH range (pH 4.5-8.5) — 4 units, acid ground through alkaline — so soil acidity is rarely what limits it in Arizona. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 5.5 and 7.5 — worth knowing before you decide whether a Arizona soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Arizona site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Arizona's soils run mostly sandy loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Annatto 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 annatto 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. Arizona soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Annatto in Arizona
Zone compatibility tells you about winter cold survival — but Arizona growers also need to think about:
Extreme heat exceeding 110F stresses most plants
Minimal rainfall requires drip irrigation
Caliche hardpan prevents root penetration without breaking through
Growing annatto here specifically
Annatto prefers pH 4.5–8.5 and room to root deep; across much of Arizona, restrictive group-D subsoil (SSURGO) blocks that depth.
Build annatto a deep raised bed of loose soil to bypass the dense subsoil entirely. How to handle it →
What to actually do about these — and the constraints that apply to every Arizona grower, not just annatto — is covered on the Arizona growing guide.
Timing shifts within Arizona
Arizona isn't one climate. In Coconino County, the last hard freeze (28°F) holds until about May 15 — roughly 78 days later than the recorded state median — so plant annatto to your county's window, not the statewide date.
Annatto needs about 150 days of frost-free season to complete its cycle. Even Coconino County — Arizona’s shortest season at 150 frost-free days — clears that by 0 days, so season length isn’t the constraint anywhere in Arizona. What varies is your own parcel.
Across Arizona’s 15 counties the frost-free season runs from 150 days in Coconino County to 345 days in Maricopa County — a spread of 195 days, which is why a single statewide planting date misleads. The median Arizona county sees 266 frost-free days, leaving annatto about 116 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"). Annatto'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
Annatto draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, annatto can only work that bloom inside Arizona's frost window — roughly 266 days, opening after the last 28°F freeze (Feb 1 - Apr 2) and closing at the first (Nov 13 - Dec 12), per NOAA Regional Climate Centers ACIS, 1991-2020.
Arizona Cooperative Extension
For Arizona-specific cultivar recommendations, planting calendars, and pest pressure for annatto, the canonical source is University of Arizona Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Annatto native to Arizona?
No — the USDA PLANTS Database lists Annatto as introduced rather than native in the Lower 48, so it is not part of Arizona's native flora. It grows here as a garden plant; pairing it with a few Arizona natives keeps local pollinators fed too.
Looking for plants that belong here? The Arizona 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 Annatto in Arizona
When can I plant Annatto in Arizona?
Arizona's last spring hard freeze (28°F) clears between Feb 1 and Apr 2, and the first fall hard freeze lands between Nov 13 and Dec 12 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Annatto, so this page does not state whether it overwinters in Arizona 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 Annatto grown in across Arizona?
Arizona spans USDA hardiness zones 5b-10b (USDA ARS PHZM 2023). Annatto 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 Arizona site have?
A typical Arizona site sees ~266 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Annatto 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 Coconino, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Annatto native to Arizona?
No — the USDA PLANTS Database lists Annatto as introduced rather than native in the Lower 48, so it is not part of Arizona's native flora. It grows here as a garden plant; pairing it with a few Arizona natives keeps local pollinators fed too.
How should I amend the soil for Annatto in Arizona?
Annatto tolerates pH 4.5-8.5 and well (dry spells) drainage (FAO ECOCROP). That is a 4-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Arizona site — amend for drainage and organic matter first.
Will Annatto actually grow on my specific land in Arizona?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores annatto 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 Arizona
State-level data is a sketch. Your Growable Ground report scores annatto against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Arizona annatto averages can't show:
We read public map data around Arizona — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Arizona annatto average
Explore More
Growing guides for annatto
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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