black locust
Robinia pseudoacacia · Fabaceae
black locust (Robinia pseudoacacia) is a perennial tree in the Fabaceae family. It is native to North America. USDA records it as hardy in zone 3 and warmer, down to about -37°F.
⚠ Invasive or noxious status. USDA lists this plant with an invasive or noxious weed status somewhere in its range. Check your state's noxious weed list before planting it — in some states it is illegal to sell or plant.
Both flags are quoted from USDA PLANTS, not inferred.
At a glance
| Type | tree USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 60 ft USDA |
| Light | full-sun USDA |
| Water need | medium USDA |
| Growth rate | rapid USDA |
| Soil pH | 4.8–8.2 USDA |
| Bloom | March–May USDA |
| Flower color | White USDA |
| Hardiness zones | 3 and warmer USDA |
| Guild layer | canopy Derived |
| Nursery availability | Routinely Available USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It needs full sun. USDA rates it as having moderate water needs. Its drought tolerance is rated high. It will not tolerate waterlogged soil — USDA rates its anaerobic tolerance as none. It is recorded on soils from pH 4.8 to 8.2 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 3.
Size and growth
At maturity it reaches about 60 ft, making it a large tree that will dominate its site. It grows quickly.
Bloom period
USDA records a bloom period of March through May. Flowers are white.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is green, medium in texture. Its flowers are conspicuous. Its fruit or seed heads are conspicuous, extending interest past flowering. Its active growth period is spring. USDA rates its lifespan as short, so plan on replacing or resowing it rather than treating it as permanent structure.
What the site needs to provide
USDA records it across sites receiving 20 to 65 inches of annual precipitation. It needs at least 140 frost-free days to finish its season. It roots to at least 36 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
It takes readily from seed, cuttings, bare root and container stock. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a moderate rate. It spreads vegetatively at a slow rate.
Resilience and wildlife
Browsing animals find it moderately palatable, so expect deer and rabbits to take an interest. Its fire tolerance is rated high, and it can resprout after damage. Its growth form is recorded as multiple stem.
Role in a guild
Canopy. In a layered planting this is the tallest layer of a planting — it sets the light budget everything beneath it lives on. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Robinia
- bristly locust Robinia hispida
- New Mexico locust Robinia neomexicana
Similar role and hardiness
- white fir Abies concolor
- shagbark hickory Carya ovata
- northern catalpa Catalpa speciosa
- Atlantic white cedar Chamaecyparis thyoides
- honeylocust Gleditsia triacanthos
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol ROPS, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, Bloom, Bloom end, browse palatability, cold stratification, Drought tolerance, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Invasive status, Lifecycle, lifespan, Light, Mature height, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
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