shrub

Spike Wattle

Acacia oxycedrus

The Story

Plant Bio

Acacia oxycedrus, commonly known as spike wattle, is an erect, rigid evergreen shrub native to southeastern Australia that forms a dense, impenetrable barrier. In winter and spring, it produces bright yellow cylindrical flower spikes along the branches in the leaf axils.

The foliage consists of stiff, dark green phyllodes that end in extremely sharp, needle-like points, making the plant highly resistant to browsing herbivores. New growth emerges with a dense covering of fine hairs before maturing to a smooth, deep green finish.

Uses & Benefits:

Produces a striking display of bright yellow cylindrical flower spikes against dark green, structured foliage.

Functions as an impenetrable natural security barrier or low hedge due to its extremely sharp, rigid phyllodes.

The dense, thorny growth provides secure nesting habitat and protection for small birds from predators.

Essentials

At a Glance

Plant Type

Shrub

Height

120"

Width

80"

Light

Full Sun, Partial Sun

Zones

8, 9, 10

Water

Low

Humidity

Low to Moderate

Lifespan

Moderate

Native To

Southeastern Australia

Toxicity

Non-toxic (mechanical irritant)

Bloom period

Winter – Spring

In flower about 6 months of the year

Planting

How to Grow

Select a planting site with full sun to partial shade and highly permeable, well-drained sandy or loamy soil.
Dig a hole twice as wide as the root ball but of equal depth, ensuring the plant sits at the same soil level as in its container.
Backfill with native soil without adding organic matter or fertilizer, then water thoroughly to settle the soil.
Apply a thin layer of organic mulch around the base, keeping it several inches away from the main stem to prevent rot.

Pro Tip

Prune only the soft tips of young branches immediately after flowering; cutting back into old, leafless wood will kill the stem as this species lacks dormant buds on mature timber.

Keep It Thriving

Care Guide

Do

Plant in sandy or well-drained soil to prevent root rot.
Tip-prune young plants regularly after flowering to maintain a compact shape.
Provide full sun to maximize flower production and maintain dense foliage.

Don't

Do not prune back into old, bare wood, as the plant cannot regenerate from old timber.
Do not apply high-phosphorus fertilizers, which can damage native Australian legumes.
Do not overwater once established, as this species is highly drought-tolerant and susceptible to wet feet.

Seasonal Care Calendar

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

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Security BarrierHedgeErosion ControlWindbreakRock Garden

Companion Plants

Banksia spinulosa Correa reflexa Leptospermum continentale Themeda triandra

Multiply

Propagation Methods

Good to Know

Common Questions

Spike Wattle questions

What zones can Spike Wattle grow in?

Spike Wattle is hardy in USDA Zones 8–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Spike Wattle deer resistant?

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

When does Spike Wattle bloom?

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

Does Spike Wattle need full sun?

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

Is Spike Wattle drought tolerant?

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