Species

Robinia pseudoacaciaBlack Locust

3 other cultivars

treeN. America Native

Globe Locust

Robinia pseudoacacia 'Umbraculifera'

The Story

Plant Bio

Robinia pseudoacacia is a deciduous North American tree characterized by deeply furrowed bark, pinnately compound leaves, and a vigorous, suckering root system. The species adapts readily to poor, dry soils through nitrogen-fixing root nodules but can spread aggressively beyond its native Appalachian and Ozark ranges.

'Umbraculifera' is a sterile, thornless cultivar distinguished by its dense, spherical canopy that naturally forms a tight 'mop-top' shape. Typically top-grafted onto a standard rootstock trunk at six to eight feet, it rarely produces the typical white pea-like flowers, focusing its energy instead on soft-textured, bright green foliage.

Uses & Benefits:

Provides a highly structured, architectural globe-headed canopy that serves as an excellent formal focal point.

Extremely drought-tolerant once established and thrives in poor, compacted soils where other trees struggle.

Offers nesting structure for birds in urban environments, though its sterile nature provides minimal forage.

SpeciesRobinia pseudoacaciaBlack Locust

Essentials

At a Glance

Plant Type

Tree

Height

315"

Width

315"

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7, 8, 9

Water

Low

Humidity

Moderate

Lifespan

30-50 years

Native To

North America

Toxicity

High

Bloom period

Spring – Summer

In flower about 6 months of the year

Planting

How to Grow

Select a planting site in full sun with excellent drainage, as wet clay soils will trigger root rot.
Dig a hole twice as wide as the root ball but no deeper, ensuring the graft union remains well above the soil line.
Stake the young standard securely to protect the top-heavy canopy from wind damage until the root system establishes.
Water deeply but infrequently once established, allowing the soil to dry out between waterings.

Pro Tip

Never prune this tree in spring when the sap is flowing rapidly, as heavy bleeding will weaken the graft union; instead, shape the canopy during winter dormancy and immediately remove any spiny suckers arising from the rootstock.

Keep It Thriving

Care Guide

Do

Prune annually during winter dormancy to maintain the tight, spherical canopy shape.
Physically dig out and sever any aggressive root suckers that emerge from the base or lawn.
Protect the trunk from lawnmowers and weed cutters to prevent bark damage.

Don't

Do not prune in spring when heavy sap flow causes excessive bleeding.
Do not cut back severely into old, leafless wood that lacks active dormant buds.
Do not apply heavy nitrogen fertilizers, as the tree fixes its own nitrogen.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Mulch
Pest Check
Prune
Spring Cleanup

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Formal garden focal pointAvenue or street plantingCourtyard specimen

Companion Plants

Cercis canadensis Salvia nemorosa Buxus sempervirens

Multiply

Propagation Methods

Good to Know

Common Questions

Globe Locust questions

What zones can Globe Locust grow in?

Globe Locust is hardy in USDA Zones 4–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Globe Locust deer resistant?

Not reliably. Deer may browse Globe Locust, especially tender spring growth — plan on repellents or fencing where pressure is high.

When does Globe Locust bloom?

Globe Locust typically blooms in spring through summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Globe Locust need full sun?

Globe Locust does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Is Globe Locust drought tolerant?

Yes — once established (usually after the first full season), Globe Locust handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.