treeN. America Native

Clammy Locust

The Story

Plant Bio

Robinia viscosa is a deciduous, suckering tree native to the southeastern United States, characterized by an open, spreading crown and twigs covered in sticky, glandular hairs. In late spring and early summer, it produces pendulous racemes of showy, dark pink to rose-purple pea-like flowers.

The species is distinguished from other locusts by the prominent, clammy secretions on its young shoots, leafstalks, and seed pods. It features alternate, pinnately compound leaves with 13 to 21 leaflets that emerge mid-green and lack the heavy thorns common to black locust.

Uses & Benefits:

Showy, pendulous rose-pink flower racemes provide striking late-spring color.

Extensive suckering root system stabilizes loose, eroding slopes and embankments.

Fixes atmospheric nitrogen to enrich poor soils and provides nectar for native bees and hummingbirds.

Essentials

At a Glance

Plant Type

Tree

Height

472"

Width

315"

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7, 8, 9

Water

Low to Medium

Humidity

Moderate to High

Lifespan

30-50 years

Native To

Southeastern United States

Toxicity

Toxic if Ingested

Bloom period

Spring – Early summer

In flower about 4 months of the year

Planting

How to Grow

Select a planting site in full sun to light shade with well-drained soil.
Dig a hole twice the width of the root ball and set the plant at its original container depth.
Water thoroughly at planting and maintain consistent moisture until the root system establishes.
Apply a layer of organic mulch around the base to suppress weeds, keeping it clear of the trunk.

Pro Tip

Prune only in late summer after flowering to prevent excessive bleeding of sap, and avoid cutting back into old, leafless wood where dormant buds fail to break.

Keep It Thriving

Care Guide

Do

Prune in late summer to avoid sap bleeding.
Wear gloves when handling to avoid mild contact dermatitis from the sticky glandular hairs.
Plant in poor or sandy soils where other trees struggle, as it fixes its own nitrogen.

Don't

Do not apply nitrogen-heavy fertilizers, which trigger excessive, weak vegetative growth.
Do not prune aggressively into old, leafless wood.
Do not plant near delicate garden beds where its aggressive root suckers will crowd out other species.

Seasonal Care Calendar

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

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Erosion ControlWindbreakNaturalized GardensSpecimen Tree

Companion Plants

Cercis canadensis Rhus typhina Symphoricarpos albus

Multiply

Propagation Methods

Good to Know

Common Questions

Clammy Locust questions

What zones can Clammy Locust grow in?

Clammy 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 Clammy Locust deer resistant?

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

When does Clammy Locust bloom?

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

Does Clammy Locust need full sun?

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

Is Clammy Locust drought tolerant?

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