Conditional — Some Areas
Surinam grass (zones 10-13) reaches only part of California (4b-11a): zones 10-11 are in range, so where you are in the state decides it.
Surinam Grass in California — the short answer
Surinam Grass in California: hardy in zones 10–13, full sun, against a state median of ~317 frost-free days.
- Plant zones
- 10-13
- 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
- Days to maturity
- 90 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.
California spans zones 4b-11a, 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 surinam grass against your land's actual soil, sun, and frost.
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California is not one climate
A single California answer averages 57 counties whose growing seasons are 257 days apart — from 108 frost-free days in Mono County to 365 in Ventura County. Which end of that your land sits nearer changes what surinam grass can finish before the first hard freeze.
The middle half of 57 counties runs 278–331 days, with a median of 317 days — a 257-day span end to end.
Measured across 57 California 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 California Fits Best
Surinam Grass is rated for zones 10–13 — 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 10–13
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 surinam grass (USDA PHZM 2023):
Zone Comparison
Surinam Grass Needs
- USDA Zones: 10-13
- Frost-Free Days: 90+
- Sun: Full Sun
- Mature size: 2 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 10-13)
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 Surinam Grass 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.
When to start the seed
Surinam Grass is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — California's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Days to maturity vs. the window
At 90 days to maturity (Growable Ground Plant Database), counting from the last hard freeze it ripens with 165 days to spare even in California'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 surinam grass survives winter in part of California, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Surinam Grass wants 90+ 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
Surinam Grass needs ~3000 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.
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
Surinam Grass likes near-neutral soil (pH 4.5-6.5). That's the common-ground band across California's alluvial clay 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 and 6 — 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 Surinam Grass 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 surinam grass — is covered on the California growing guide.
Timing shifts within California
Surinam Grass needs about 90 days of frost-free season to complete its cycle. Even Mono County — California’s shortest season at 108 frost-free days — clears that by 18 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 surinam grass about 227 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"). Surinam Grass's 90-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
California Cooperative Extension
For California-specific cultivar recommendations, planting calendars, and pest pressure for surinam grass, the canonical source is UC Agriculture and Natural Resources. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Surinam Grass in California
When can I plant Surinam Grass 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). 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 Surinam Grass mature before first frost in California?
Yes — Surinam Grass matures in 90 days (Growable Ground Plant Database), and California's dependable hard-freeze-free window runs 255 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 165 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 Surinam Grass grown in across California?
California spans USDA hardiness zones 4b-11a (USDA ARS PHZM 2023). Surinam Grass carries a range of zones 10-13, 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). Surinam Grass needs 90+ 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 Surinam Grass in California?
Surinam Grass prefers pH 4.5-6.5 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across California soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Surinam Grass actually grow on my specific land in California?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores surinam grass 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 surinam grass against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that California surinam grass averages can't show:
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