Black Locust is a tree, a long-term addition to the landscape. It's hardy across USDA zones 3 through 8 and shrugs off dry spells. Its spring flowers are a real draw for honeybees and native bees. A nitrogen-fixer, it draws nitrogen from the air and feeds it back to the soil — turn it under or leave the roots in place, and the next planting inherits a richer bed.
Zones
3-8
pH Range
4.5-8.2
Sun
Full Sun
Days to Maturity
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Score Black Locust on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether black locust actually takes — and those shift from one yard to the next. Enter your address and we'll score black locust against your land's real conditions.
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What Black Locust is
Black Locust grows as a perennial and reaches around 50 feet at maturity. It blooms white in spring.
How to grow Black Locust
Black Locust grows in USDA zones 3 through 8. Black Locust does best in full sun — at least 6 hours of direct sun a day — and soil from pH 4.5 to 8.2, on well-drained ground. It needs a growing season of at least 120 frost-free days and about 800 hours of winter chill, which is why climate matters as much as soil.
USDA Zones
3-8
USDA PHZM 2023
Soil pH
4.5 - 8.2
USDA PLANTS Database
Sun
Full Sun
plant_species_v5.csv
Drainage
well (dry spells)
plant_species_v5.csv
Frost Tolerance
42.8°F
plant_species_v5.csv
Mature Height
50 ft
plant_species_v5.csv
Chill Hours
800+
plant_species_v5.csv
Frost-Free Days
120+
plant_species_v5.csv
Plant it right
Set black locust in full sun with well-drained soil. Many fruit trees need a second variety nearby to pollinate — check before you plant just one.
Match the soil
Black Locust prefers pH 4.5 to 8.2 (USDA PLANTS Database). A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band. It fixes its own nitrogen, so skip the high-nitrogen feed and instead dust the seed with a matching rhizobium inoculant at sowing.
Water steadily
Keep the root zone evenly moist through establishment. A 2–3 inch mulch layer holds moisture without waterlogging.
Be patient, then harvest
Prune annually while the tree establishes; fruit trees reward patience with years of harvest. Local Extension guides publish per-cultivar bearing-age tables.
Good to know
One caution for pet owners — black locust is toxic to dogs and cats and horses (severe severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)
Black Locust is a standout pollinator plant — high value to bees and other pollinators. (Source: Xerces Society, Pollinator Partnership.)
Where Black Locust thrives
Black Locust is hardy across USDA zones 3 through 8. 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 3–8·Where Black Locust growsOpen map →
On USDA hardiness-zone overlap, Black Locust can grow in these states:
See if Black Locust will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether black locust 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 Locust in my zone?
Black Locust grows in USDA hardiness zones 3 through 8 (USDA PHZM 2023). Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
When should you plant Black Locust?
Set black locust out in early spring or fall while it's dormant, so the roots establish before the heat of summer. Your local last-frost date — which a Growable Ground report pulls for your exact address — sets the precise window.
How much sun does Black Locust need?
Black Locust 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 Locust need?
Black Locust prefers soil pH 4.5 to 8.2, on well-drained ground (USDA PLANTS Database). Your report scores your parcel's actual soil against that using USDA SSURGO data.
Does Black Locust attract pollinators?
Yes — black locust's flowers are a strong nectar and pollen source for honeybees and native bees (Xerces Society, Pollinator Partnership).
Is Black Locust safe for pets?
Black Locust is toxic to pets (dogs,cats,horses) with severe severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency.