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.
Black Locust — the short answer
Black Locust: grown in zones 3–8, full sun, pH 4.5–8.2.
- USDA zones
- 3–8
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Soil pH
- 4.5–8.2
- FAO ECOCROP
- Sun
- Full Sun
- Growable Ground Plant Database
- Frost-kill temperature
- 30.2°F
- FAO ECOCROP
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.
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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
FAO ECOCROP
Sun
Full Sun
Growable Ground plant catalog
Drainage
well (dry spells)
Growable Ground plant catalog
Frost Kill Temperature
30.2°F
Where cold starts killing growing tissue. Not a winter-survival floor — a dormant perennial takes far colder, which its hardiness zone answers.
FAO ECOCROP
Minimum Growing Temperature
42.8°F
Below this it stops growing rather than dies — a pace limit, not a survival limit.
FAO ECOCROP
Mature Height
50 ft
Growable Ground plant catalog
Chill Hours
800+
Winter hours below ~45°F it needs to fruit — too-mild winters can leave it bloom-shy.
Growable Ground plant catalog
Frost-Free Days
120+
The frost-free stretch it needs start to finish — short-season areas may need an indoor head start.
Growable Ground plant catalog
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 (FAO ECOCROP). 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.
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.
A USDA zone is a 10°F band of average annual extreme winter minimum, so zones 3–8 spans average winter lows from -40°F to 20°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 34 outright and splits 17 more down the middle — and which side of that line your land sits on changes the answer.
Zones 3–8·Where Black Locust growsOpen map →
Where Black Locust stands, state by state
Black Locust is rated for zones 3–8 — a cold floor USDA puts at -40 to -30°F. Across the 50 states and DC, 34 sit fully inside that band, the line runs through 17 more, and 0 sit outside it — and inside every split state, the same line runs on at county grain.
Fully inside zones 3–8
34 states
3 of 34 shown
The line runs through
17 states
- Alaska · zones 1a-9a
- California · zones 4b-11a
- Nevada · zones 4a-10a
3 of 17 shown
Black Locust’s band covers part of each of these states — which side of the line your county sits on changes the answer, and each state page draws it.
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 Locust
Growing guides for black locust
In rotation planning, black locust counts as a Legume — beds recover best when legume crops don’t follow each other in the same spot year over year. (Growable Ground derivation — crop-rotation group from botanical family)
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: Cornell Poisonous Plants Database.)
Black Locust is a standout pollinator plant — high value to bees and other pollinators. (Source: Xerces Society.)
Your land is one point inside Black Locust'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 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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How we know this about Black Locust
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•USDA PHZM•ASPCA
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 (FAO ECOCROP). 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. (Source: Xerces Society.)
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. (Source: Cornell Poisonous Plants Database.)