Generally — Most Areas
rakkyo (zones 5-10) partially overlaps with Utah (4a-8a). It can grow in zones 5-8 within the state.
Your yard isn't the whole zone.
Utah spans zones 4a-8a, 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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Zone Comparison
Rakkyo Needs
- USDA Zones: 5-10
- Soil pH: 4.3 - 7.2
- Sun: Full Sun
- Drainage: well (dry spells)
- Frost-Free Days: 45+
Utah Has
- USDA Zones: 4a-8a
- Last Frost: Apr 10 - Jun 1
- First Frost: Sep 15 - Oct 25
- Annual Rainfall: 5-20 inches
- Common Soils: Sandy loam, Alkaline clay, Desert sand
Plant Zone Range (zones 5-10)
Preferred Soil pH
Plant data: USDA PLANTS Database / plant_species_v5.csv. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Rakkyo in Utah
The frost window
Across Utah, the last spring frost clears between Apr 10 and Jun 1, and the first fall frost lands between Sep 15 and Oct 25 (NOAA Climate Normals 1991-2020). Counting from the latest last frost to the earliest first frost, that's a 106-day window you can count on — up to 198 days on a mild site in a kind year.
Frost tenderness
Rakkyo is frost-tender — its listed minimum temperature is 46.4°F (USDA PLANTS Database) — so set plants out after the last frost has cleared your local site, not the state's earliest date.
Days to maturity vs. the window
At 150 days to maturity (USDA PLANTS Database), the fit is tight: Utah's dependable window runs 106 days. Starting seeds indoors and transplanting at the front of the window banks the difference.
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.
Growing Season Fit
Zone compatibility says you can survive winter here. Whether the growing season is long enough — and warm enough — is a different question.
Frost-free days
Rakkyo wants 45+ frost-free days; a typical Utah site sees ~190 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Growing degree days
Rakkyo needs ~1400 GDD (base 50°F) to ripen. The state median runs ~3850 GDD (USDA NRCS county aggregates), so Utah's typical season clears that easily.
Climate aggregates derive from USDA NRCS county-level hardiness data + Cornell CALS Extension GDD-by-region tables + MSU Extension chill-hours-by-zone (1991-2020 NOAA Climate Normals baseline).
Soil + Drainage Fit
Rakkyo likes near-neutral soil (pH 4.3-7.2). That's the common-ground band across Utah's sandy loam and alkaline clay — a soil test confirms it for your site. Drainage matters: this plant wants well (dry spells). If your Utah site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. Utah soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Rakkyo in Utah — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 5-10 (USDA PLANTS Database)
- State Zones: 4a-8a (USDA ARS PHZM 2023)
- Growing Season: Apr 10 - Jun 1 to Sep 15 - Oct 25 (NOAA Climate Normals)
- Days to Maturity: 150 days
What Else to Consider
Zone compatibility tells you about winter cold survival — but Utah growers also need to think about:
Very low rainfall — irrigation essential
Design the drip system before the beds — with mulch over it, high-desert ground grows on a fraction of the water you'd guess.
Alkaline soils (pH 7.5-8.5) limit many species
A soil test pins your actual pH — adapted species take the ground, acid-lovers take containers, nothing is off the table.
High altitude frost risk in mountain valleys
Mountain valleys trade on frost dates, not zone — know your real window and keep row covers close in the shoulder weeks.
Pollinator + Wildlife Value
Rakkyo draws pollinators (moderate value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops.
Utah Cooperative Extension
For Utah-specific cultivar recommendations, planting calendars, and pest pressure for rakkyo, 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 Rakkyo in Utah
When can I plant Rakkyo in Utah?
Utah's last spring frost clears between Apr 10 and Jun 1, and the first fall frost lands between Sep 15 and Oct 25 (NOAA Climate Normals 1991-2020). Rakkyo is frost-tender — its listed minimum temperature is 46.4°F (USDA PLANTS Database) — so wait until the last frost has cleared your specific site before planting out.
Can Rakkyo mature before first frost in Utah?
It's close: Rakkyo needs 150 days to mature (USDA PLANTS Database) against Utah's 106-day dependable window (NOAA Climate Normals 1991-2020). Start seeds indoors and transplant right after last frost to bank the missing days.
What hardiness zone is Rakkyo grown in across Utah?
Utah spans USDA hardiness zones 4a-8a (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 Utah site have?
A typical Utah site sees ~190 frost-free days per year (derived from NOAA Climate Normals 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 Utah?
Rakkyo prefers pH 4.3-7.2 and well (dry spells) drainage (USDA PLANTS Database). 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 Rakkyo actually grow on my specific land in Utah?
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 Utah
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 exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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