Unlikely — Zone Mismatch
blue clitoria (zones 13-13) does not overlap with California's zone range (4b-11a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Blue Clitoria is hardy to zone 13, and the warmest ground in California is zone 11 — 2 zones short. Planted in open ground it will not survive a California winter. To grow it here, grow blue clitoria in an earth-sheltered greenhouse — its modeled 2.5-zone lift covers this gap.
An earth-sheltered greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 13-13 (plant) against 5-11 (California). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['earth_sheltered'] (+2.5 zones) via api/fast_sections.py Unlock Engine v2.
Blue Clitoria in California — the short answer
Blue Clitoria in California: hardy in zones 13–13, full sun, against a state median of ~317 frost-free days.
- Plant zones
- 13-13
- 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
- California zones
- 4b-11a
- USDA PHZM 2023
- Frost window
- Jan 19 - Mar 19 – Nov 29 - Dec 12
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 108 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.
California spans zones 4b-11a, 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 blue clitoria 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 full report in seconds
California is not one climate
California’s winter-low ladder runs across 58 counties, from zone 6 in Mono County to zone 10.5 in San Francisco County. That is 45°F between the two counties’ average coldest night — the difference between blue clitoria overwintering in the ground and coming under cover.
The middle half of 58 counties runs 9–9.5 zones, with a median of 9.5 zones — a 4.5-zone span end to end.
Measured across 58 California 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 Blue Clitoria Stands in California
Blue Clitoria is rated for zones 13–13 — a cold floor USDA puts at 60 to 70°F. No California 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 California winters, not about blue clitoria.
Below the zone 13 floor
58 counties
- Mono County · zone 6a
- Alpine County · zone 6b
- Lassen County · zone 7a
3 of 58 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
Blue Clitoria Needs
- USDA Zones: 13-13
- Frost-Free Days: 50+
- Sun: Full Sun
- Mature size: 10 ft tall
- Drought tolerance: Medium
California Has
- USDA Zones: 4b-11a
- Last Hard Freeze (28°F): Jan 19 - Mar 19
- First Hard Freeze (28°F): Nov 29 - Dec 12
- Annual Rainfall: 5-80 inches
- Common Soils: Alluvial clay, Sandy loam, Adobe clay
Plant Zone Range (zones 13-13)
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 Blue Clitoria in California
The frost window
Across California, the last spring hard freeze (28°F) clears between Jan 19 and Mar 19, and the first fall hard freeze lands between Nov 29 and Dec 12 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 255-day window you can count on — up to 327 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
California runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for blue clitoria, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether blue clitoria is a permanent planting or a replant-every-spring crop for you turns on your own zone within California; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Mono 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 blue clitoria does not survive a California winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on California under protection.
Frost-free days
Blue Clitoria wants 50+ frost-free days; a typical California site sees ~317 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Blue Clitoria needs ~3500 GDD (base 50°F) to ripen. The state median runs ~4290 GDD (from PRISM 1991-2020 climate normals), so California's typical season clears that easily.
Chill hours
Blue Clitoria has no winter-chill requirement — its listed minimum is 0 hours (Growable Ground Plant Database). California typically banks ~1172 chill hours per winter (from PRISM 1991-2020 climate normals), so chill is not a constraint on this plant here — and not evidence in its favour either. Winter survival and season length are what decide it.
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
Blue Clitoria tolerates a wide pH range (pH 4.5-9) — 4.5 units, acid ground through alkaline — so soil acidity is rarely what limits it in California. 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 6.5 and 7.5 — worth knowing before you decide whether a California soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your California site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
California's soils run mostly loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Blue Clitoria needs about 19 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 blue clitoria 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. California soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant blue clitoria 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 blue clitoria goes in. What follows is California’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 California — and how to grow with it.
We checked the federal record across California — 254,277 documented sites across 8 of the 9 source types we track.
The most significant on record: 1073 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
California 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.
Sources Checked
across California
Severity Distribution
across California
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around California, Brownfields runs higher than the national average — 196,551 sites across California. That's not a problem with your land — it's information about it.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Blue Clitoria in California
Zone compatibility tells you about winter cold survival — but California growers also need to think about:
Drought is a persistent challenge — irrigation is essential in most regions
Wildfire risk affects rural and foothill properties
Adobe clay soils in valleys drain poorly without amendment
Wide climate variation means plant selection is highly location-specific
Growing blue clitoria here specifically
Blue Clitoria prefers pH 4.5–9.0 and room to root medium; across much of California, restrictive group-D subsoil (SSURGO) blocks that depth.
Build blue clitoria 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 California grower, not just blue clitoria — is covered on the California growing guide.
Timing shifts within California
California isn't one climate. In Mono County, the last hard freeze (28°F) holds until about Jun 4 — roughly 120 days later than the recorded state median — so plant blue clitoria to your county's window, not the statewide date.
Blue Clitoria needs about 50 days of frost-free season to complete its cycle. Even Mono County — California’s shortest season at 108 frost-free days — clears that by 58 days, so season length isn’t the constraint anywhere in California. What varies is your own parcel.
Across California’s 57 counties the frost-free season runs from 108 days in Mono County to 365 days in Ventura County — a spread of 257 days, which is why a single statewide planting date misleads. The median California county sees 317 frost-free days, leaving blue clitoria about 267 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"). Blue Clitoria's 50-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
Blue Clitoria draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, blue clitoria can only work that bloom inside California's frost window — roughly 317 days, opening after the last 28°F freeze (Jan 19 - Mar 19) and closing at the first (Nov 29 - Dec 12), per NOAA Regional Climate Centers ACIS, 1991-2020.
California Cooperative Extension
For California-specific cultivar recommendations, planting calendars, and pest pressure for blue clitoria, the canonical source is UC Agriculture and Natural Resources. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Blue Clitoria native to California?
No — the USDA PLANTS Database lists Blue Clitoria as introduced rather than native in the Lower 48, so it is not part of California's native flora. It grows here as a garden plant; pairing it with a few California natives keeps local pollinators fed too.
Looking for plants that belong here? The California 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 Blue Clitoria in California
When can I plant Blue Clitoria in California?
California's last spring hard freeze (28°F) clears between Jan 19 and Mar 19, and the first fall hard freeze lands between Nov 29 and Dec 12 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Blue Clitoria, so this page does not state whether it overwinters in California 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 Blue Clitoria grown in across California?
California spans USDA hardiness zones 4b-11a (USDA ARS PHZM 2023). Blue Clitoria carries a range of zones 13-13, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical California site have?
A typical California site sees ~317 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Blue Clitoria needs 50+ 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 Mono, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Blue Clitoria native to California?
No — the USDA PLANTS Database lists Blue Clitoria as introduced rather than native in the Lower 48, so it is not part of California's native flora. It grows here as a garden plant; pairing it with a few California natives keeps local pollinators fed too.
How should I amend the soil for Blue Clitoria in California?
Blue Clitoria tolerates pH 4.5-9 and well (dry spells) drainage (FAO ECOCROP). That is a 4.5-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a California site — amend for drainage and organic matter first.
Will Blue Clitoria actually grow on my specific land in California?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores blue clitoria 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 California
State-level data is a sketch. Your Growable Ground report scores blue clitoria against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that California blue clitoria averages can't show:
We read public map data around California — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the California blue clitoria average
Explore More
Growing guides for blue clitoria
Explore California county by county
California carries 58 counties with their own USDA zone — a sample of the growing pages for blue clitoria there:
Where else blue clitoria grows
Blue Clitoria's zone band crosses state lines — these are the states closest to California 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 California
California has a growing page for 1,046 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
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