Grass Tree – Xanthorrhoea Care Tip Introduction

The Grass Tree, Xanthorrhoea, is the quintessential Australian native plant, certainly plant royalty, perhaps even the King! It is famous for its distinctive black trunk and magnificent crown of grassy leaf strands, which earned it the now much dated nickname of Blackboy or Black Boy Plant. It’s actually not a grass, or a tree for that matter but are actually distantly related to lilies. Grass trees come in a wide variety of species (28 in total) with different sizes, colours and shapes and the family grows naturally right across Australia’s diverse landscapes and are native only to Australia. They are believed to be as old as 35 million years so they were certainly kicking it with the Dinosaurs and individual plants can live up to 600 years old (so stats should make you feel nice and young!). Great as a specimen plant for any garden or to soften up some harsh edges on rockeries. Once established they are generally very low maintenance and quite drought tolerant. In the bush they are even quite famous for being fire tolerant, where they will sacrifice their foliage and grow back relatively undeterred. Xanthorrhoeas are a protected species. They are a famously slow grower, sometimes growing as little as a couple of centimeters per year in height. This slow growing nature has made them vulnerable to poaching not only in the wild but as a popular plant to steal from front yards. They are a statement piece for their architectural form, dramatic colouring, an Australian Icon and for their price tag so best to place it in a spot that won’t be easy for thieves to take. Plants that have been harvested must be done under licence and must be tagged with a registration code so make sure you buy from a reputable dealer.

Grass Tree – Xanthorrhoea Soil & Drainage

Xanthorrhoeas are a protected species. They are a famously slow grower, sometimes growing as little as a couple of centimeters per year in height. This slow growing nature has made them vulnerable to poaching not only in the wild but as a popular plant to steal from front yards. They are a statement piece for their architectural form, dramatic colouring, an Australian Icon and for their price tag so best to place it in a spot that won’t be easy for thieves to take. Plants that have been harvested must be done under licence and must be tagged with a registration code so make sure you buy from a reputable dealer.

Grass Tree – Xanthorrhoea Lighting and Position

Choose a location that receives full sun or partial shade, and make sure that it’s protected from strong winds. Since grass trees don’t enjoy being moved, it’s important to pick the perfect spot in your garden right from the start.

Grass Tree – Xanthorrhoea Watering

Grass tree is a very tough plant that is able to withstand drought. However, if kept in pots they must be watered regularly. After planting the tree will need regular water until the roots settle and grow. Established Grass Trees will benefit from watering during dry periods. For most of the year natural rainfall should be enough to keep your Grass Tree happy.

Grass Tree – Xanthorrhoea Fertilizer

Grass trees aren’t really fussy but as a slow grower it’s not a bad idea to help it along. Grass Trees will benefit from a light feed of dynamic lifters or blood and bone in October and January. Also half a cup of raw sugar mixed in a watering can may be beneficial for the microbial activity necessary for good root growth. The grass tree will also benefit from a regular application of seaweed solution which is a good root conditioner.

We recommend using our Plant Food available here. 

Grass Tree – Xanthorrhoea Pests and Diseases

Watch out for grubs in the crown when the trees are flowering. Treat with a pyrethrin spray. If the leaves are yellowing or new growth is soft or limp, then it is most likely a result of poor drainage. Grass trees also suffer from Cinnamon fungus which causes root rot. Good drainage is the key as this fungus thrives in waterlogged soils. Xanthorrhoea australis are sensitive to Phytophthora cinnamomi, a widespread plant pathogen that restricts the movement of water and nutrients to the plant. It is difficult to detect and control and it kills the plant and has devastated populations in the wild. In National Parks you’ll occasionally see areas to wash your shoes to clean off any potential pathogens.

For more information on how to manage common plant pests, head to our blog here.

How to promote Root Growth

You need to encourage its root system for the grass tree to really thrive. Regular deep watering can help with this, as can using a liquid seaweed fertilizer for the first few months after planting. Some Experts recommend applying a mixture of brown sugar and water to the soil surrounding your grass tree for the first couple of years after planting – this feeds the mycorrhiza in the soil, enabling the tree’s roots to grow bigger and stronger.

Grass Tree – Xanthorrhoea Design Tips

Grass Trees are generally a fairly substantial investment, especially if purchasing a more mature specimen, so of course you want it to be a prominent feature plant. With it’s striking black trunk you’ll most likely want this contrasting against a lighter background such as a white wall but any plain, timber or corten steel background with not too much distraction should be enough to give it some pop. You’ll also want it in a prominent spot where you can enjoy it every day like along your driveway or near your front door, the main thing to be wary of is theft. Illuminating it at night can also help to do it justice! As a whole they are a very rugged and rustic looking plant so you can exaggerate that with old rustic pots or concrete. It does look great against other rustic materials like weathered timber, rusty corten steel or rough concrete.