Australian Grass Tree
Xanthorrhoea preissii
A skirt of fine leaves on a woody trunk — heavy, wet ground will finish it long before any pest does.
- Type
- Grass · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Green
- Sunlight
- Full sun
- Feeding
- Gentle all-organic
- Frost tolerant
- Yes
- Flowering
- May
- Mar–May Spring Growth
- May–Dec Flowering
- Jan–Mar Flowering
- Plant spacing
- 4 ft 11 in
- In-row spacing
- 4 ft 11 in
- Between rows
- 6 ft 2 in
- Square-foot density
- Not suited to SFG
- Root system
- A fleshy crown with thick perennial roots
- Working depth
- 12 in–3 ft
- Can reach
- 5 ft down where the soil allows
- Spread
- 5–7.5 ft across, about 1–1.5× the width of the plant
- Shallowest pot
- 18 in of soil
The crown is the plant’s bank account and it is slow to rebuild, which is why a new planting is left unpicked for a season or two. Plant it at the depth it asks for and no deeper; these rot from being buried far more often than they suffer from being shallow.
The trunk is a slow accumulation of old leaf bases over a fleshy underground stem, and the roots below depend on a soil fungus. That partnership is why a grass tree dug from the bush almost always dies and why nursery-grown plants are the only sensible ones to buy.
The habit is Australian Grass Tree’s own; the figures are what that habit usually comes to at this size, not a measurement of this species. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Hoverfly SyrphidaeHunts Scale insects
Bee-mimicking flies whose legless larvae graze aphid colonies clean while the adults pollinate. A ribbon of shallow, nectar-rich flowers kept in bloom all season recruits wave after wave of them.
- Ladybird (lady beetle) CoccinellidaeHunts Scale insects
The gardener’s favorite ally: adults and their alligator-shaped larvae each eat thousands of aphids, plus scale, mealybugs, and other soft-bodied sap-suckers. Grow flat, open flowers for the adults and never spray a colony that ladybird larvae are already working.
Kangaroo Paw (Anigozanthos), Grevillea, Banksia, Lomandra
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com