Generally — Most Areas
black seed (zones 5-10) suits most of Hawaii (8b-13a) — zones 8-10 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Black Seed is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Hawaii site runs ~365 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score black seed against your land's actual frost dates, sun, and soil.
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Zone Comparison
Black Seed Needs
- USDA Zones: 5-10
- Frost-Free Days: 90+
- Sun: Full Sun
- Mature size: 1.3 ft tall
- Picking window: ~21 days of harvest
- Drought tolerance: Medium
Hawaii Has
- USDA Zones: 8b-13a
- Hard Freeze (28°F): None on record — year-round season
- Annual Rainfall: 10-400 inches
- Common Soils: Volcanic, Laterite, Coral sand
Plant Zone Range (zones 5-10)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Black Seed in Hawaii
The frost window
Hawaii has none — the 1991-2020 station record carries no 28°F killing freeze, so there is no last-frost date to plant after and no first-frost date to harvest before (NOAA Regional Climate Centers ACIS station record). The growing season is year-round; what paces planting here is rainfall, heat and elevation, not the calendar.
Days to maturity vs. the window
At 100 days to maturity (USDA PLANTS Database) and no frost to close the season, black seed fits about 3 plantings a year — so the real limit is what you can keep watered and harvested, not how many days are left.
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
The zone check says black seed survives winter in part of Hawaii, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Black Seed wants 90+ frost-free days; a typical Hawaii site sees ~365 (NOAA Regional Climate Centers ACIS station record, 1991-2020). That leaves comfortable headroom for succession planting.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS station record, 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
Black Seed likes near-neutral soil (pH 5.5-8). That's the common-ground band across Hawaii's volcanic and laterite — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 7.5 — worth knowing before you decide whether a Hawaii soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Hawaii 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. Hawaii soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Black Seed in Hawaii — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 5-10 (USDA PLANTS Database)
- State Zones: 8b-13a (USDA ARS PHZM 2023)
- Growing Season: year-round — no 28°F killing freeze in Hawaii’s 30-year station record (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 100 days
What Else to Consider for Black Seed in Hawaii
Zone compatibility tells you about winter cold survival — but Hawaii growers also need to think about:
Extreme rainfall variation — desert on one side, rainforest on the other
Volcanic soil is nutrient-poor in young flows
Invasive species pressure is severe
What to actually do about these — and the constraints that apply to every Hawaii grower, not just black seed — is covered on the Hawaii growing guide.
Timing shifts within Hawaii
Black Seed needs about 90 days of frost-free season to complete its cycle. Even Hawaii County — Hawaii’s shortest season at 365 frost-free days — clears that by 275 days, so season length isn’t the constraint anywhere in Hawaii. What varies is your own parcel.
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"). Black Seed's 90-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
Black Seed draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Black Seed's flowers are not fenced in by a freeze date here: the 1991-2020 record resolves no 28°F killing frost anywhere in Hawaii, so what limits bloom is the plant's own cycle rather than the calendar.
Hawaii Cooperative Extension
For Hawaii-specific cultivar recommendations, planting calendars, and pest pressure for black seed, the canonical source is UH Mānoa CTAHR Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Black Seed native to Hawaii?
No — the USDA PLANTS Database lists Black Seed as introduced rather than native in the Lower 48, so it is not part of Hawaii's native flora. It grows here as a garden plant; pairing it with a few Hawaii natives keeps local pollinators fed too.
Looking for plants that belong here? The Hawaii 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 Black Seed in Hawaii
When can I plant Black Seed in Hawaii?
Any month — Hawaii records no 28°F killing freeze in the 1991-2020 station record, so there is no last-frost date to wait for and the growing season is year-round (NOAA Regional Climate Centers ACIS station record). Pace planting by rainfall, heat and elevation instead: the summit country does freeze, and no station up there carries a long enough record to date it.
What hardiness zone is Black Seed grown in across Hawaii?
Hawaii spans USDA hardiness zones 8b-13a (USDA ARS PHZM 2023). Black Seed 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 Hawaii site have?
A typical Hawaii site sees ~365 frost-free days per year (derived from NOAA Regional Climate Centers ACIS station record, 1991-2020). Black Seed needs 90+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Black Seed native to Hawaii?
No — the USDA PLANTS Database lists Black Seed as introduced rather than native in the Lower 48, so it is not part of Hawaii's native flora. It grows here as a garden plant; pairing it with a few Hawaii natives keeps local pollinators fed too.
How should I amend the soil for Black Seed in Hawaii?
Black Seed prefers pH 5.5-8 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across Hawaii soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Black Seed actually grow on my specific land in Hawaii?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores black seed 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 Hawaii
State-level data is a sketch. Your Growable Ground report scores black seed against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Hawaii black seed averages can't show:
We read public map data around Hawaii — soil, climate, flood, and parcel records. How we handle your address.
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