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.
|
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. €36 | approx. €34 |
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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