Black Seed is an annual culinary herb, grown for the flavor it brings to the kitchen, ready to harvest about 100 days after planting. Season length, not a winter zone, decides where it grows. Notably, it stands up to deer and grows just as well in a container as in the ground. Its summer flowers are a moderate draw for honeybees and native bees, even though the harvest is the prize.
Black Seed — the short answer
Black Seed: grown in zones 5–10, full sun, pH 5.5–8, about 100 days to maturity.
- USDA zones
- Grown as an annual — see the growing season
- Growing season, not a hardiness zone
- Soil pH
- 5.5–8
- We haven't confirmed this against a published source yet.
- Sun
- Full Sun
- We haven't confirmed this against a published source yet.
- Days to Maturity
- 100 days
- We haven't confirmed this against a published source yet.
- Frost-kill temp (growing season)
- 28°F
- We haven't confirmed this against a published source yet.
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — each tile names its own row's source, because per-field provenance varies.
Score Black Seed on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether black seed actually takes — and those shift from one yard to the next. Enter your address and we'll score black seed against your land's real conditions.
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What Black Seed is
Black Seed grows as an annual and reaches around 1.3 feet at maturity. It blooms blue in summer. It's also deer-resistant and well suited to containers.
Life cycle, mature height, bloom period, flower colour, deer resistance and container suitability: We haven't confirmed this against a published source yet.
How to grow Black Seed
Season length, not a winter zone, decides where black seed grows; it is ready to harvest about 100 days after planting. Black Seed does best in full sun — at least 6 hours of direct sun a day — and soil from pH 5.5 to 8, on well-drained ground. It needs around 1,500 growing degree days to mature and a growing season of at least 90 frost-free days, which is why climate matters as much as soil.
USDA Zones
Grown as an annual — see the growing season
Soil pH
5.5 - 8
We haven't confirmed this against a published source yet.
Sun
Full Sun
We haven't confirmed this against a published source yet.
Drainage
well (dry spells)
We haven't confirmed this against a published source yet.
Frost Kill Temperature
28°F
Where cold starts killing growing tissue. Not a winter-survival floor — a dormant perennial takes far colder, which its hardiness zone answers.
We haven't confirmed this against a published source yet.
Days to Maturity
100 days
Black seed (kalonji); annual; harvest mature seed pods.
We haven't confirmed this against a published source yet.
GDD Required
1500+
Growing degree-days of accumulated warmth it needs to mature — humid summers reach this faster than cool coastal ones.
We haven't confirmed this against a published source yet.
Mature Height
1.3 ft
We haven't confirmed this against a published source yet.
Frost-Free Days
90+
The frost-free stretch it needs start to finish — short-season areas may need an indoor head start.
Growable Ground plant catalog
Start the season right
Plant black seed in full sun with at least 6 hours of direct sun, once the soil has warmed and frost risk has passed. We haven't confirmed this against a published source yet.
Match the soil
Black Seed prefers pH 5.5 to 8. We haven't confirmed this against a published source yet. A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band.
Water steadily
Keep the root zone evenly moist through establishment. We haven't confirmed this against a published source yet. A 2–3 inch mulch layer holds moisture without waterlogging.
Harvest at maturity
Black Seed is ready about 100 days after planting. We haven't confirmed this against a published source yet. Snip sprigs as you need them — regular cutting keeps the foliage tender and slows it bolting to flower.
Where Black Seed thrives
Season length, not a winter zone, decides where black seed grows. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
A USDA zone is a 10°F band of average annual extreme winter minimum, so zones 5–10 spans average winter lows from -20°F to 40°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 29 outright and splits 21 more down the middle.
Zones 5–10·Hardiness bandOpen map →
This map is derived from the USDA ARS / PRISM Plant Hardiness Zone Map (2023) and is not the official USDA Plant Hardiness Zone Map.
Where Black Seed stands, state by state
Black Seed is rated for zones 5–10 — a cold floor USDA puts at -20 to -10°F. Across the 50 states and DC, 29 sit fully inside that band, the line runs through 21 more, and 1 sits outside it — and inside every split state, the same line runs on at county grain.
Fully inside zones 5–10
29 states
3 of 29 shown
The line runs through
21 states
3 of 21 shown
State zone extents: USDA Plant Hardiness Zone Map (PHZM) 2023. A zone is a 10°F band of average annual extreme minimum temperature, so a state that splits the band contains the boundary — its own page draws the county line, and a parcel report resolves which side your land sits on.
What grows around Black Seed
Growing guides for black seed
Good to know
One caution for pet owners — black seed is toxic to dogs and cats (mild severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: Pet Poison Helpline.)
Black Seed offers moderate value to bees and other pollinators. We haven't confirmed this against a published source yet.
Before you harvest black seed, know your soil
Anything you grow to eat takes up what's in the ground it grows in, so it's worth knowing what's documented near you before you plant black seed for food. Our free screen reads 8 federal source types across roughly 950K indexed sites and shows which sit near your address and which way they drain. It's a screening estimate from public records and proximity — not a soil test — so a nearby record means a soil test is worth it, not that your soil is unsafe.
Your land is one point inside Black Seed's range
This page resolves to the species. Your state page draws the county line, and a report reads the parcel — the soil pH, drainage, sun, and frost dates on your exact ground, which no species average can see.
See if Black Seed will thrive on your land
Zone averages are a start. Your soil pH, drainage, sun exposure, and frost dates shape whether black seed actually takes. We score it against the mapped and modelled conditions at your address.
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.
25+ data sources analyzed in seconds
How we know this about Black Seed
The figures above are cited per row, not per site: the pH band names this plant’s own source column, the three temperature figures each carry their own, and days-to-maturity cites the publication that actually lists it. All of it comes from the Growable Ground Plant Database — a compilation over FAO ECOCROP, USDA PLANTS, and university Extension sources, published openly with per-field provenance.
Grounded inUSDA PLANTS Database
Frequently asked questions
Can I grow Black Seed in my zone?
Black Seed is grown as an annual, so a hardiness zone does not decide it — its growing season follows your last and first frost dates. Soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
How long does Black Seed take to grow?
Black Seed is ready to harvest about 100 days after planting. We haven't confirmed this against a published source yet. Your local frost dates and soil temperature move that window earlier or later.
When should you plant Black Seed?
Most growers plant black seed after the last spring frost, once the soil has warmed, leaving enough of the season for its 90-day frost-free need. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does Black Seed need?
Black Seed needs full sun — a spot that catches at least 6 hours of direct summer sun a day. We haven't confirmed this against a published source yet. In more shade it still grows, but usually gives a smaller, later crop. The catch is that a yard rarely gets even light everywhere — a fence, the house, or one tall tree can quietly take those hours. A Growable Ground report reads the real sun-hours across your land, canopy and buildings included, so you can pick the brightest bed before you plant.
What soil does Black Seed need?
Black Seed prefers soil pH 5.5 to 8, on well-drained ground. We haven't confirmed this against a published source yet. Your report scores your parcel's mapped soil against that using USDA SSURGO data.
Does Black Seed attract pollinators?
Yes — black seed's flowers are a solid nectar source for honeybees and native bees. We haven't confirmed this against a published source yet.
Is Black Seed safe for pets?
Black Seed is toxic to dogs and cats with mild severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: Pet Poison Helpline.)
Keep exploring Black Seed
Black Seed state by state
Every state black seed's zone reaches — 18 link straight to that state's black seed growing page; the rest open the state's full growing guide.