# Black locust (Robinia pseudoacacia)

> A fast-growing, thorny, nitrogen-fixing tree of 15 to 25 m with fragrant white pea flowers that make prized honey and very rot-resistant timber. Introduced to Paris around 1602, it is now one of the most widespread trees in Europe and regarded as invasive in most European countries, where it suckers into dry grasslands and enriches the soil with nitrogen, squeezing out rare native plants. Not on the EU list of Union concern, but regulated in Portugal and listed as invasive in Switzerland, Luxembourg and South Africa.

Source: https://treerm.org/trees/robinia-pseudoacacia · Updated 2026-11-08 · License CC BY 4.0

## Facts

- Also called: False acacia, Robinia
- Family: Fabaceae
- Type: Broadleaf, loses its leaves in winter
- Mature height: 20 m; spread 12 m
- Growth: Fast growing; lives about 90 years
- USDA hardiness zones: 3 to 8
- Light: Full sun
- Water: Low water
- Soil: Almost any well-drained soil including poor, sandy and alkaline ground; not saturated soils
- Native range: Native to the Appalachian and Ozark regions of the eastern and central United States (Pennsylvania to Georgia, Alabama, Tennessee and Kentucky); naturalised across the rest of the USA, Europe, Asia and the southern hemisphere.

**Benefits:** Fixes nitrogen, Pollinators, Drought tolerant, Fast canopy, Holds soil, Flowers

**Good for:** Timber, Reforestation, Windbreak

**Watch out for:** Invasive elsewhere, Thorns, Weak wood, Toxic parts, Large roots

## Care

Needs no watering once established and tolerates heat and drought. Prune in late summer or autumn, never spring, when it bleeds. Expect vigorous root suckers, brittle branches that snap in wind, and seedlings everywhere; bark, leaves and seeds are poisonous to people and livestock. Locust borer and leaf miner attack it. Not recommended for gardens; where it is already established, cutting alone stimulates suckering.

## Where it stands

- **Native:** AL, United States (Appalachian native range.); AR, United States (Ozark and Ouachita native range.); GA, United States; KY, United States; MO, United States (Ozark and Ouachita native range.); NC, United States (Appalachian native range.); OK, United States (Ozark and Ouachita native range.); PA, United States; TN, United States; VA, United States; WV, United States (Appalachian native range.)
- **Adapted:** Germany (Introduced and widely naturalised per WCVP; EPPO notes it is considered invasive in most European countries); United Kingdom (Introduced and naturalised per WCVP; no GB statutory listing found); Hungary (Introduced; a major plantation and honey tree per ICRAF)
- **Invasive:** ON, Canada (Listed as an invasive plant by the Ontario Invasive Plant Council; USDA PLANTS lists it as introduced in Canada.); Switzerland (On the Swiss List of Invasive Alien Plants (2013)); Luxembourg (Luxembourg Black List (ISEIA A3); established since the 18th century); Portugal (EPPO: regulated invasive alien plant in Portugal since 1999); CT, United States (Invasive on the Connecticut Invasive Plant List; statutory sale ban takes effect October 2028.); IL, United States (Considered invasive in the Midwest outside its native range); MA, United States (Rated Invasive by the Massachusetts Invasive Plant Advisory Group and banned from sale under the state Prohibited Plant List.); NY, United States (Regulated invasive species under 6 NYCRR Part 575.); South Africa (NEMBA 2020 Category 1b: must be controlled; may not be sold or planted)
- **Prohibited:** MN, United States (Restricted Noxious Weed in Minnesota: cannot be imported, sold or transported.); WI, United States (Restricted under Wisconsin NR 40 (all cultivars exempt).)
- **Recommended:** Sydney, NSW, Australia (On the City of Sydney Street Tree Master Plan 2023 precinct planting palette); Washington, DC, United States (On the Casey Trees Tree Rebate eligible species list)

## Sources

- https://plants.ces.ncsu.edu/plants/robinia-pseudoacacia/
- https://gd.eppo.int/taxon/ROBPS/categorization
- https://www.neobiota.lu/robinia-pseudoacacia
- https://plants.usda.gov/DocumentLibrary/plantguide/pdf/pg_rops.pdf
- https://apps.worldagroforestry.org/treedb2/speciesprofile.php?Spid=1454
- https://faolex.fao.org/docs/pdf/saf220858.pdf
- https://www.gbif.org/species/5352251