Black locust and Empress tree are often considered for the same spot in the garden (shade, flowers, specimen). The data below shows where they differ: size, hardiness, care, toxicity and price.
Robinia pseudoacacia 8 m × 5 m after 10 years
A fast-growing, drought-tolerant tree from North America with an open crown, pinnate leaves and fragrant white flower clusters in late May. It is sold…
Paulownia tomentosa 10 m × 7 m after 10 years
An extremely fast-growing tree with huge, velvety, heart-shaped leaves that carries foxglove-like, pale violet, vanilla-scented flower panicles before…
Black locust: We do not recommend it for most Central European gardens.
Empress tree: We do not recommend it because it is on the EU or the Hungarian list of invasive species.
Black locust is hardier: down to -40 °C, against -29 °C for Empress tree.
Black locust tolerates drought better than Empress tree.
Black locust needs less water than Empress tree.
Black locust needs less care than Empress tree.
Empress tree is cheaper: about €26 at the size usually planted, against about €50 for Black locust.
|
Feature
|
Black locust
|
Empress tree
|
|---|---|---|
| Group | Large tree | Large tree |
| Size after 10 years | 8 m × 5 m | 10 m × 7 m |
| Ultimate size | 6–25 m × 4–18 m | 10–20 m × 8–12 m |
| Growth rate | Fast | Fast |
| Light | Full sun | Full sun |
| Soil | Average garden soil, Sandy, Clay, Calcareous | Average garden soil, Sandy, Calcareous |
| Hardiness | down to -40 °C (USDA 3, RHS H7) | down to -29 °C (USDA 4, RHS H7) |
| Foliage | Deciduous | Deciduous |
| Flowering | May–June, white | April–May, purple |
| Water need | Low | Medium |
| Drought tolerance | High | Medium |
| Maintenance | Medium | High |
| Planting distance | 800 cm | 1000 cm |
| For dogs | Toxic | no data |
| For cats | Toxic | no data |
| For children | Toxic | Non-toxic (uncertain) |
| Typical price | approx. €50 | approx. €26 |
Prices are rounded, indicative values. Toxicity data is for information only. If your pet or child has eaten a plant, contact a vet or a doctor. Data updated: October 8, 2026
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