groundcover

Prostrate Swamp Oak

Casuarina glauca 'Cousin It'

The Story

Plant Bio

Casuarina glauca, native to the eastern coast of Australia, grows as an upright tree in brackish coastal swamps and estuarine margins. The species features slender, segmented branchlets that function as leaves and performs exceptionally well in salty, wind-swept environments.

'Cousin It' is a prostrate, sterile cultivar that forms a dense, mounding groundcover of cascading, needle-like green branchlets. It spreads horizontally to drape over retaining walls and rocks without producing flowers or seeds.

Uses & Benefits:

Forms a dense, cascading green carpet that softens hardscapes, drapes over walls, and suppresses weeds.

Excellent for stabilizing slopes and controlling erosion on steep banks due to its wide-spreading root system.

Provides dense ground cover that shelters small beneficial insects and ground reptiles.

Essentials

At a Glance

Plant Type

Groundcover

Height

18"

Width

96"

Light

Full Sun, Partial Sun

Zones

Water

Low

Humidity

High

Lifespan

Perennial

Native To

Australia

Toxicity

Non-toxic

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 level with the soil surface.
Backfill with native soil, pressing firmly to eliminate air pockets, and water thoroughly.
Apply a light layer of mulch around the base, keeping it clear of the main stem to prevent rot.

Pro Tip

Avoid shearing into old, leafless woody stems, as this prevents new growth from regenerating and leaves permanent bare patches.

Keep It Thriving

Care Guide

Do

Water regularly until the root system is fully established.
Ensure the soil drains freely to prevent waterlogging around the root zone.
Prune lightly along the edges to maintain the desired spread.

Don't

Do not cut back into old, bare woody stems.
Do not over-irrigate once the plant is established in the landscape.
Do not plant in low-lying areas prone to standing water.

Seasonal Care Calendar

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

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

GroundcoverErosion ControlRock GardenRetaining Wall SpilloverCoastal Garden

Companion Plants

Juniperus horizontalis Gazania Rosmarinus officinalis

Multiply

Propagation Methods

Good to Know

Common Questions

Prostrate Swamp Oak questions

What zones can Prostrate Swamp Oak grow in?

Prostrate Swamp Oak is hardy in USDA Zone 10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Prostrate Swamp Oak deer resistant?

Yes — Prostrate Swamp Oak is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

Does Prostrate Swamp Oak need full sun?

Prostrate Swamp Oak does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Is Prostrate Swamp Oak drought tolerant?

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