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.
Take a cup of brown sugar, put it in a bucket of water and water your grass trees once a month for two years with that mixture. The sugar feeds the mycorrhiza and gets it going and your grass tree will survive.
Fully established grass trees will only need the water from the sky. Old foliage forms a skirt around the trunk as it dies back and that's completely natural. If the number of dead-leaves start to fully envelop the canopy of the tree, you're in trouble. It may be a sign of overwatering which causes root-rot.
Grass trees can go into decline if there drainage is not very good. They dislike having waterlogged roots and in fact resent any kind of root disturbance as they have a very special relationship with certain fungi that live in the ground – without healthy fungi you wont have healthy grass trees.
But in reality, grass trees have an amazing ability to survive – and going dormant for long periods of time is one of those strategies that make grass tree stunningly unique. Patience and consistent watering is the best way to nurture it through this dormancy period. Regular seasol won't hurt either.
Grass Tree – Xanthorrhoea Fertilizer
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.
Do not apply Seasol and PowerFeed during the heat of the day. As PowerFeed is a fertiliser it may burn the foliage of the plant or lawn. If fungal problems are an issue, it is best to apply Seasol and PowerFeed in the morning to avoid moisture residue on the foliage overnight.
Yates Dynamic Lifter and Acticote+Instant Booster are great fertilisers for grass trees.
Most species are extremely slow growing . Studies of some of the taller species found that trunk height increases at about 0.8cm to 6cm per year, but this varies with local environmental conditions 1 . In any event, grass trees are often very long-lived; some are estimated to be 350 to 450 years old !
No Pruning Needed
Leaving a healthy grass tree alone to grow as it will is probably a perfectly viable choice. There are, however, some caveats that could indicate that pruning is both necessary and desirable. These include fire prevention, esthetics and perhaps the health of the plant itself.
Root disease — root rot
It is usually present in damp or poorly drained soils but will also survive drought. As a result the central leaves wilt and turn brown, causing the crown to collapse and the trunk to rot. Phosphorous acid sprays can be applied in the early stages of decline.
The most common reason for grass trees to die is too much or too little water. This can be from either too little rainfall or from irrigation systems not working properly. They are susceptible to pollution and all manner of environmental stresses.
All grass trees have a fibrous root system typical of monocots that extends into the soil from the base of the leaves. The unusual roots are contractile (able to shrink) and the apex of plants can be 10cm below the ground surface.
Grass tree is low-maintenance if correctly replanted with the original soil. You can feed it with a native compatible fertiliser every 6 to 12 months. The only disease this resilient plant contracts is scale, a white insect that appears on the tree's inner crown. White oil helps to treat scale quickly.
Xanthorrhoea can be grown in pots or containers though better suited to planting in the garden. These highly drought hardy plants can be easily over-watered so care must be taken especially in heavy soils. Grass trees prefer a full sun position, though they can be in a slightly shady spot.
Grass trees can readily grow from seed, however, the growth is slow and a reasonable specimen can take 3 to 5 years to develop. Be careful not to overwater. Grass trees don't like getting wet feet.
Give Your Grass Tree Enough Water, But Not Too Much
Once or twice a week is usually enough during dry spells in the summer, but make sure that you keep the actual trunk of your grass tree as dry as possible – too much water on the trunk will soften it, leaving it vulnerable to pests and diseases.
Xanthorrhoea australis, the grass tree, austral grasstree or blackboy, is an Australian plant.
The best method of transplanting is as follows: Trim off the leaves of the grass-tree with shears, or tie them up with string, to avoid damage to your eyes. Dig around the base of the plant severing the old roots. You only need to dig a few centimetres away from the trunk to avoid damaging it.
Apply Seasol regularly for several months before any fertilising is done. Once the tree is starting to respond to the Seasol treatment, apply an organic fertiliser such as Dynamic Lifter, blood and bone or slow-release tree tablets. Note: Sadly, some trees will be damaged beyond repair.
Blood and Bone, Chicken Manure or Fish Meal
Slow release type fertilisers are great for the health of your turf, providing a slow consistent supply of nutrient, rather than one quick burst.
Inhalation: Material may be an irritant to mucous membranes and respiratory tract. Skin contact: Repeated or prolonged skin contact may lead to irritation. Ingestion: Swallowing can result in nausea, vomiting and irritation of the gastrointestinal tract.
You can't overdose on Seasol. It's not a Fertiliser. But it does have amazing healing qualities. One capful in a 10 litre watering can will treat around 4m2.
Do I need to water in after apply Seasol or PowerFeed? Seasol and PowerFeed are liquids, they are readily absorbed into the soil and the plant foliage. Therefore you do not need to water them in.
Seasol is especially effective when used directly onto foliage as it's absorbed through the leaves. Seasol promotes healthy roots, encourages beneficial soil micro-organisms, stimulates flowering and fruiting and helps plants to cope with stresses like heat, drought, frost and pest and disease attack.