Conditional — Some Areas
triffid weed (zones 10-12) reaches only part of California (4b-11a): zones 10-11 are in range, so where you are in the state decides it.
Triffid Weed in California — the short answer
Triffid Weed in California: hardy in zones 10–12, full sun, against a state median of ~317 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
- 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 triffid weed against your parcel's actual hardiness, soil, and sun.
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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 triffid weed 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 in California Fits Best
Triffid Weed is rated for zones 10–12 — a cold floor USDA puts at 30 to 40°F. Against California’s 58 counties that band holds in 7 of them, and the line runs at Los Angeles County (zone 10a), the coldest county still inside it.
Inside zones 10–12
7 counties
- San Mateo County · zone 10a
- Santa Barbara County · zone 10a
- Ventura County · zone 10a
3 of 7 shown
Below the zone 10 floor
51 counties
- Mono County · zone 6a
- Alpine County · zone 6b
- Lassen County · zone 7a
3 of 51 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.
Even within California's zones 4b-11a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for triffid weed (USDA PHZM 2023):
Zone Comparison
Triffid Weed Needs
- USDA Zones: 10-12
- Sun: Full Sun
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 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 Triffid Weed 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 triffid weed, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether triffid weed 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.
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
Triffid Weed tolerates a wide pH range (pH 4-7.5) — 3.5 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 5 and 6.5 — 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.
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.
What Else to Consider for Triffid Weed 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
What to actually do about these — and the constraints that apply to every California grower, not just triffid weed — is covered on the California growing guide.
Where in California Triffid Weed Is Zone-Hardy
Triffid Weed is rated for USDA zones 10–12. 7 of California’s 58 counties fall inside that band. The coldest that does is Los Angeles County at zone 10a. 51 counties sit below the plant’s zone 10 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in California decides this one.
Across those 58 counties California’s winter-low ladder runs from zone 6a in Mono County to zone 10b in San Francisco County — 4.5 USDA zones of spread, which is 45°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Mono County holds its last hard freeze (28°F) until about Jun 4, while Marin County is clear by Jan 9 — 146 days apart. Set triffid weed out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Triffid Weed’s zone 10–12 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Triffid Weed 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, triffid weed 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 triffid weed, 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 Triffid Weed native to California?
Triffid Weed is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in California. It can still earn a place in a California garden — the zone comparison above tells you whether it will thrive.
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 Triffid Weed in California
When can I plant Triffid Weed 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 Triffid Weed, 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 Triffid Weed grown in across California?
California spans USDA hardiness zones 4b-11a (USDA ARS PHZM 2023). Triffid Weed 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 California site have?
A typical California site sees ~317 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Triffid Weed should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Triffid Weed native to California?
Triffid Weed is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in California. It can still earn a place in a California garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Triffid Weed in California?
Triffid Weed tolerates pH 4-7.5 and well (dry spells) drainage (FAO ECOCROP). That is a 3.5-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 Triffid Weed actually grow on my specific land in California?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores triffid weed 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 triffid weed against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that California triffid weed 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 triffid weed average
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