Yes — Strong Match
sunn hemp (zones 7-11) fits entirely within California's zone range (5a-11a).
Your yard isn't the whole zone.
Sunn Hemp is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is, and slope, trees, and low spots move the last-frost date across a single yard. Enter your address and we'll score sunn hemp against your parcel's actual frost dates, sun, and soil.
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Zone Comparison
Sunn Hemp Needs
- USDA Zones: 7-11
- Soil pH: 5 - 8.4
- Sun: Full Sun
- Drainage: well (dry spells)
- Frost-Free Days: 60+
California Has
- USDA Zones: 5a-11a
- Last Frost: Jan 15 - May 15
- First Frost: Oct 1 - Dec 31
- Annual Rainfall: 5-80 inches
- Common Soils: Alluvial clay, Sandy loam, Adobe clay
Plant Zone Range (zones 7-11)
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 Sunn Hemp in California
The frost window
Across California, the last spring frost clears between Jan 15 and May 15, and the first fall frost lands between Oct 1 and Dec 31 (NOAA Climate Normals 1991-2020). Counting from the latest last frost to the earliest first frost, that's a 139-day window you can count on — up to 350 days on a mild site in a kind year.
Frost tenderness
Sunn Hemp is frost-tender — its listed minimum temperature is 39.2°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 90 days to maturity (USDA PLANTS Database), a planting right after last frost ripens with 49 days to spare even in California's tightest frost scenario — room for a later start or a second sowing.
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
Sunn Hemp wants 60+ frost-free days; a typical California site sees ~220 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Growing degree days
Sunn Hemp needs ~2200 GDD (base 50°F) to ripen. The state median runs ~3850 GDD (USDA NRCS county aggregates), so California'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
Sunn Hemp likes near-neutral soil (pH 5-8.4). That's the common-ground band across California's alluvial clay and sandy loam — a soil test confirms it for your site. 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 and drainage requirements from USDA PLANTS Database. California soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Sunn Hemp in California — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: 7-11 (USDA PLANTS Database)
- State Zones: 5a-11a (USDA ARS PHZM 2023)
- Growing Season: Jan 15 - May 15 to Oct 1 - Dec 31 (NOAA Climate Normals)
- Days to Maturity: 90 days
What Else to Consider
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
Design the water system before the plants: drip lines plus a thick mulch layer run a full garden on surprisingly little water.
Wildfire risk affects rural and foothill properties
Keep plantings low, lean, and well-watered near structures — your extension office publishes firewise landscaping guides for your county.
Adobe clay soils in valleys drain poorly without amendment
Work in compost over seasons, or skip the fight with a raised bed — adobe's nutrients are excellent once drainage is solved.
Wide climate variation means plant selection is highly location-specific
Zones run 5a to 11a in one state — check your exact zone before trusting any statewide planting list.
Pollinator + Wildlife Value
Sunn Hemp draws pollinators (moderate value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops.
California Cooperative Extension
For California-specific cultivar recommendations, planting calendars, and pest pressure for sunn hemp, 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 Sunn Hemp native to California?
No — the USDA PLANTS Database lists Sunn Hemp 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 Sunn Hemp in California
When can I plant Sunn Hemp in California?
California's last spring frost clears between Jan 15 and May 15, and the first fall frost lands between Oct 1 and Dec 31 (NOAA Climate Normals 1991-2020). Sunn Hemp is frost-tender — its listed minimum temperature is 39.2°F (USDA PLANTS Database) — so wait until the last frost has cleared your specific site before planting out.
Can Sunn Hemp mature before first frost in California?
Yes — Sunn Hemp matures in 90 days (USDA PLANTS Database), and California's dependable frost-free window runs 139 days (NOAA Climate Normals 1991-2020), leaving 49 days of margin. Plant just after last frost and it ripens ahead of the first fall frost.
What hardiness zone is Sunn Hemp grown in across California?
California spans USDA hardiness zones 5a-11a (USDA ARS PHZM 2023). Sunn Hemp carries a range of zones 7-11, 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 ~220 frost-free days per year (derived from NOAA Climate Normals 1991-2020). Sunn Hemp needs 60+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Sunn Hemp native to California?
No — the USDA PLANTS Database lists Sunn Hemp 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 Sunn Hemp in California?
Sunn Hemp prefers pH 5-8.4 and well (dry spells) drainage (USDA PLANTS Database). 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 Sunn Hemp actually grow on my specific land in California?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sunn hemp 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 sunn hemp 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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