What you will see
Branches suddenly wilt and die back; it occurs rarely but can be fatal.
How to protect
Rare, but can be fatal; contact an expert.
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Tree · Fabaceae family
Black locust
Robinia pseudoacacia
Full sun in a garden ~16 ft 4⅞ in × ~13 ft 1½ in Flowers May–June to −93 °F
Flower colors Click a color
In short a 10-second read
SunFull sun
in a garden after 10 years~16 ft 4⅞ in
in the wild up to 82 ft
spacing 19 ft 8¼ in
in the wild up to 82 ft
spacing 19 ft 8¼ in
FlowersMay–June
PlantingMarch–April, October–November
WinterNo winter protection
Where to plant and how much to water
Sun, soil and water.
It grows best in full sun, in dry to average soil.
Sun
Sun6 hours or more
Part shade3–6 hours
Shadeunder 3 h
Soil
tolerates any pH
acidicneutralalkaline
Watering
Frost
−93 °F
How much space it takes
Mature size.
The mature plant next to a person (69 in).
49.2 ft–82 ft× spread 19 ft 8¼ in–65.6 ft
Plant 19 ft 8¼ in apart.
Reaches maturity in about 20–50 years. The final size depends on the cultivar and the spot — we give the range from smallest to largest.
Calendar
Through the year.
Typical for a temperate climate (four seasons). The line shows the current month.
The year at a glance
FlowersPlantingFeeding
Now, in October: a good time for planting (container plant, bare-root, root-balled).
JanFebMarAprMayJunJulAugSepOctNovDec
Flowers
JanFebMarAprMayJunJulAugSepOctNovDec
May–June · white
Planting
JanFebMarAprMayJunJulAugSepOctNovDec
container plant: March–April, October–November; bare-root: March–April, October–November; root-balled: March–April, October–November
Feeding
JanFebMarAprMayJunJulAugSepOctNovDec
May–June
Feeding
Nutrition.
Horn meal
up to 0.18 oz/sq ft a year, if the soil needs it · May–June
JanFebMarAprMayJunJulAugSepOctNovDec
Pests and diseases
Common problems and what to do.
The most common problems in Central Europe. Protection is listed from the gentlest option.
Verticillium wiltdisease
What you will see
Branches suddenly wilt and die back; it occurs rarely but can be fatal.
How to protect
Rare, but can be fatal; contact an expert.
Sources (1)
Frequently asked
Quick answers.
When does black locust flower?
In May–June; the flowers are white.
Does black locust tolerate shade?
No, it needs full sun.
How much space does black locust need?
At maturity 19 ft 8¼ in–65.6 ft wide and 49.2 ft–82 ft tall; recommended spacing 19 ft 8¼ in.
Sources (15) Checked 24 October 2026
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Uses
In the garden and at home.
Pollinators
many