Black Seed is an annual culinary herb, grown for the flavor it brings to the kitchen, ready to harvest about 100 days after planting. It's hardy across USDA zones 5 through 10, 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.
Zones
5-10
pH Range
5.5-8
Sun
Full Sun
Days to Maturity
100
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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.
How to grow Black Seed
Black Seed grows in USDA zones 5 through 10 and 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
5-10
USDA PHZM 2023
Soil pH
5.5 - 8
USDA PLANTS Database
Sun
Full Sun
Growable Ground plant catalog
Drainage
well (dry spells)
Growable Ground plant catalog
Days to Maturity
100 days
Black seed (kalonji); annual; harvest mature seed pods.
USDA-NRCS
GDD Required
1500+
Growing degree-days of accumulated warmth it needs to mature — humid summers reach this faster than cool coastal ones.
Growable Ground plant catalog
Mature Height
1.3 ft
Growable Ground plant catalog
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.
Match the soil
Black Seed prefers pH 5.5 to 8 (Growable Ground Plant Database). 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. A 2–3 inch mulch layer holds moisture without waterlogging.
Harvest at maturity
Black Seed is ready about 100 days after planting (USDA-NRCS). Snip sprigs as you need them — regular cutting keeps the foliage tender and slows it bolting to flower.
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.
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 9 federal source types across roughly 1.8M 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.
Where Black Seed thrives
Black Seed is hardy across USDA zones 5 through 10. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
Zones 5–10·Where Black Seed growsOpen map →
On USDA hardiness-zone overlap, Black Seed can grow in these states:
See if Black Seed will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether black seed actually takes — we score it against the real 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.
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Frequently Asked Questions
Can I grow Black Seed in my zone?
Black Seed grows in USDA hardiness zones 5 through 10 (USDA PHZM 2023). Zone is one factor — 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 (USDA-NRCS). 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. 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 (Growable Ground Plant Database). Your report scores your parcel's actual 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.
Is Black Seed safe for pets?
Black Seed is toxic to pets (dogs,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.)