perennial

Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca

The Story

Plant Bio

Xanthorrhoea australis, commonly known as the Austral grass-tree, is a long-lived, slow-growing perennial endemic to the dry sclerophyll forests and coastal heaths of southeastern Australia. Over many decades, it develops a thick, fire-charred trunk topped with a dense, spherical crown of narrow, arching leaves.

This species is distinguished by its blue-grey to glaucous green leaves that have a characteristic diamond-shaped cross-section. Following bushfires, it produces a massive, spear-like flowering spike up to two metres long covered in nectar-rich, cream-coloured flowers.

Uses & Benefits:

Provides a dramatic, architectural silhouette with a charcoal-black trunk and a spherical crown of fine, blue-grey foliage.

Highly drought-tolerant and fire-adapted, making it ideal for low-maintenance, water-wise landscapes.

The towering flower spikes produce abundant nectar that supports native bees, butterflies, and nectar-eating birds.

Essentials

At a Glance

Plant Type

Perennial

Height

118 inches

Width

59 inches

Light

Full Sun

Zones

9, 10

Water

Low

Humidity

Moderate

Lifespan

Long-lived

Native To

Southeastern Australia

Toxicity

Non-toxic

Bloom period

Winter – Summer

In flower about 7 months of the year

Planting

How to Grow

Select a planting site in full sun with exceptional, rapid drainage, such as a raised bed or sandy slope.
Dig a hole twice as wide as the rootball but to the exact same depth, ensuring the trunk base sits level with the surrounding soil.
Gently slide the plant from its container without disturbing the soil or root system, and backfill with native soil.
Water deeply at the base immediately after planting to settle the soil, then withhold water unless conditions are extremely dry.

Pro Tip

Never disturb or wash the rootball during planting, as this destroys the vital symbiotic mycorrhizal soil fungi required for nutrient uptake and causes sudden plant collapse months later.

Keep It Thriving

Care Guide

Do

Ensure the soil drains rapidly to prevent fatal root rot.
Use only phosphorus-free native fertilisers if feeding is necessary.
Water strictly at the base of the plant, keeping the leaf crown dry.

Don't

Never prune into old, bare wood or cut into the living trunk.
Do not disturb or wash the rootball during planting.
Avoid planting in heavy clay or waterlogged soils.

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

Architectural focal pointXeriscape and low-water gardensCoastal gardens in second-line positionsNative wildlife gardens

Companion Plants

Anigozanthos flavidus Banksia spinulosa Correa reflexa

Multiply

Propagation Methods

Good to Know

Common Questions

Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca questions

What zones can Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca grow in?

Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca is hardy in USDA Zones 9–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

When does Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca bloom?

Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca typically blooms in winter through summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca need full sun?

Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca does best in full sun (6+ hours).

Is Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca drought tolerant?

Yes — once established (usually after the first full season), Austral Grass-tree, Grass Tree, Blackboy, Kangaroo Tails, Yacca handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.