Yes — Strong Match
rakkyo (zones 5-10) covers every zone Arizona contains (5b-10b), so hardiness is not what limits it anywhere in the state.
Rakkyo in Arizona — the short answer
Rakkyo in Arizona: hardy in zones 5–10, full sun, against a state median of ~266 frost-free days.
- Plant zones
- 5-10
- 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
- Days to maturity
- 150 days
- Growable Ground Plant Database
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 has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score rakkyo against your land's actual soil, sun, and frost.
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Arizona is not one climate
A single Arizona answer averages 15 counties whose growing seasons are 195 days apart — from 150 frost-free days in Coconino County to 345 in Maricopa County. Which end of that your land sits nearer changes what rakkyo can finish before the first hard freeze.
The middle half of 15 counties runs 207–316 days, with a median of 266 days — a 195-day span end to end.
Measured across 15 Arizona counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. 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 in Arizona Fits Best
Even within Arizona's zones 5b-10b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for rakkyo (USDA PHZM 2023):
Zone Comparison
Rakkyo Needs
- USDA Zones: 5-10
- Frost-Free Days: 45+
- Sun: Full Sun
- Mature size: 1.5 ft tall
- Picking window: ~21 days of harvest
- Drought tolerance: Medium
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 5-10)
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 Rakkyo 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.
Days to maturity vs. the window
At 150 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 75 days to spare even in Arizona's tightest freeze scenario — room for a later start or a second sowing.
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 rakkyo survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Rakkyo wants 45+ frost-free days; a typical Arizona site sees ~266 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Rakkyo needs ~1400 GDD (base 50°F) to ripen. The state median runs ~3945 GDD (from PRISM 1991-2020 climate normals), so Arizona's typical season clears that easily.
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
Rakkyo likes near-neutral soil (pH 4.3-7.2). That's the common-ground band across Arizona's caliche and sandy loam — 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 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.
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.
Before you plant rakkyo 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 rakkyo goes in. What follows is Arizona’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 Arizona — and how to grow with it.
We checked the federal record across Arizona — 32,297 documented sites across 7 of the 9 source types we track.
The most significant on record: 184 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Arizona 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 with clean imported soil grow well almost anywhere in the meantime.
Severity Distribution
across Arizona
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Arizona, two things run higher than the national average across Arizona — Mining (6,160 sites) and Nitrate (11,388 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Rakkyo 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
What to actually do about these — and the constraints that apply to every Arizona grower, not just rakkyo — is covered on the Arizona growing guide.
Timing shifts within Arizona
Rakkyo needs about 45 days of frost-free season to complete its cycle. Even Coconino County — Arizona’s shortest season at 150 frost-free days — clears that by 105 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 rakkyo about 221 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"). Rakkyo's 45-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
Rakkyo 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, rakkyo 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 rakkyo, the canonical source is University of Arizona Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Rakkyo in Arizona
When can I plant Rakkyo 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). 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 Rakkyo mature before first frost in Arizona?
Yes — Rakkyo matures in 150 days (Growable Ground Plant Database), and Arizona's dependable hard-freeze-free window runs 225 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 75 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Rakkyo grown in across Arizona?
Arizona spans USDA hardiness zones 5b-10b (USDA ARS PHZM 2023). Rakkyo carries a range of zones 5-10, 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). Rakkyo needs 45+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
How should I amend the soil for Rakkyo in Arizona?
Rakkyo prefers pH 4.3-7.2 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Arizona soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Rakkyo actually grow on my specific land in Arizona?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores rakkyo 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 rakkyo against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Arizona rakkyo 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 rakkyo average
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Growing guides for rakkyo
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