Xanthorrhoea species (Grass Trees)
Xanthorrhoea priessii is a Western Australian species. This species was one of the plants used by the winning garden at the Chelsea Flower Show. Xanthorrhoea quadrangulata and Xanthorrhoea semiplana are the South Australian species of Grass Tree.
At an Arboretum near here, Xanthorrhoea preissii and Xanthorrhoea semiplana have both been planted on deep sand. After four years of growth in the ground, the cluster of leaves is about 60cm tall and beginning to ‘vase’ out in a very graceful way. The width of the clump is larger than the reach of two hands joined finger tip to finger tip as if holding a large bunch of flowers.
It is certainly worth while growing these for the leaf display if this is what the growth is like after 4 years. Xanthorrhoea semiplana generally does not make a trunk although sometimes one up to a metre will appear, whereas the other does to about 3 metres tall. However to see a ‘decent’ trunk on Xanthorrhoea semiplana in one’s lifetime is probably only to be dreamed about!
Xanthorrhoea need a sunny well drained position. They look wonderful growing in a rockery and will also look great in a large pot as an impressive feature plant. Specimens have flowered after 7 years in Brisbane and 10 years at the Australian National Botanic Gardens.
It has been discovered that the Yellow Tailed Black Cockatoos love the seed pods that form along the flower stem which can be as much as 4-5 metres tall. They have been observed eating them soon after sunrise between Tintinara and Keith on the side of the road.
[...] Xanthorrhoea species (Grass Tree) from Kalbarri WA .Photo by Jeff A friend, Jeff, emailed this photo to me wondering about the botanical name (which he found for himself before I had read his email.) He said the photo was taken at Kalbarri in WA so I thought it probably was specifically Xanthorrhoea priessii when I looked up a reference. Then I realised that I had called the trunkless species by this name in a previous post. [...]
CAn you please give me some feedback to help me with a successful transplantation of semi mature grass trees. What will help them survive?
I would be really greatful of some advice to keep them alive. They look great, what will help me keep them going?
Do I need to cut them back?
[...] After the grasses seminar we went to Cromer Conservation Park for a picnic lunch. Husband had been bird watching there and was distracted by the great display of wildflowers. There were a number of these Xanthorrhoea plants in flower. They were growing on deep very well drained sand. [...]
Every plant that I have seen ready for transplanting has had the leaves trimmed to around 30cm or less, I assume to reduce transpiration stress.
They do not have an extensive root system. They need good drainage, so raise the planting spot if needed, and give it an open sunny aspect. Keep moist but not soggy, so test the soil in the top 4-5cm for dryness before watering again. I think a mulch of small gravel or course sand, failing that, leaf litter to retain moisture during the summer and keep soil temperature from extremes while the plant is establishing is a good idea.
Hi.
I am wanting to find out a little infomation in regards to a blackboy plant that i have in my backyard. The plant is about 6 years old, and this year was the first time it flowered. The plant has always been extremely healthy, but within 1 week it looks like it has started to die. I am unsure if it has to do with the large 8ft flower, if that is draining the plant, do not know if to cut the flower off, or if it is normal for the plant to go brown, which i would doubt, as all the foilage has drooped down to the ground and not standing up. Nothing has really changed in its environment, only climate.
Your help would be much appreciated, as it would be a shame to see this beautiful plant die.
Thanks.
Jamie.
Hi Jamie,
I have not heard of Xanthorrhoea dying off like you describe. I wonder if you have changed your watering pattern and the plant has received too much water and the drainage is not as good as it was. It seems from everything I have read that good drainage is very important.What a shame to lose a plant so well grown and at flowering stage. It is probably worth while excavating around the plant reasonably close to the trunk to check moisture levels. The root system is not extensive. You may be able to save the plant by cutting foliage back heavily and transplanting into a postion with improved drainage.
Hi,
I would like some information please. We have a Blackboy tree that is 4 metres tall and the trunk is about 2 metres. We know that it must be really old. The 5 heads have been dropping off over the last 3 years. On inspection down the arm where the head fell of it appears brown and muddy. Is this normal? and is the trunk hollow? It would be a shame to loose it.
Thanks
Nigel
It sounds like you have rot in the stems as what you describe is not normal. I would cut below the rot area until you come to solid stem and treat the area with a fungicide such as ‘Fongarid’ or some thing that is available for painting on fruit trees that suffer collar rot. Wash whatever you make the cuts with in disinfectant.
I wonder if the tree is under the canopy of other trees which drop leaf litter and bark? If so and it is possible cut back the overhanging branches. In any case I would regularly clean leaf litter from the crowns. Has the drainage around the root zone of your tree changed? It would be a shame to lose such a well grown tree.
Hi Connie, thanks for your reply does the collar rot progress down the whole trunk of the tree, as it is a very large grass tree. There is no overhanging trees and the drainage system hasnt changed. If you lean on the trunk the whole tree wobbles is it usually that moveable. Would controlled burning be of any benefit we havent tried this we have been in the house for nearly 4 years and the tree was here when we moved in. As you say we would hate to loose such an old tree, and it is a great feature in our garden.
Thanks
Nigel
hello
I’m living in Switzerland. 1 year ago I brought me a blackboy tree. It’s a beauty! Now, since about 3 month, 3 young xanthorreas are growing up realy quick from the ground. They now about 35 cm tall. The mother plant is about 100cm tall. Is it a good or a bad sign? I know, in Switzerland we have a complet different clima than in Australia. Can you give me a few hints for our special cold clima? Thanks a lot for your help!
Hi,
I have bought a property with some established black boys. Do they actually need pruning?
Thanks for your help.
I have never heard of a need to prune other than to tidy the leaves perhaps when any die off. You also may like to remove the old flower spikes. Lucky you to have established plants.
Thanks for your reply Corinne. One last thing, we notice that some people burn the trunk of these trees. Do you recommend this?
Hi, I’ve just returned from a trip to the Fleurieu Peninsula in South Australia and was particularly impressed with the number of Xanthorrhoea Semiplana in the Deep Creek Conservation Park. I know they are extremely slow growing but want to buy some seeds and try growing them in Melbourne. Any ideas where I can buy these? I’m a little skeptical of overseas sites so a local site (ie Vic or SA) would be great. Thanks for your help, Tom
Hi, I am about to plant a 300lt xanthorrhoea preissi in an awkward site. It may loose a lot of soil from the root during this process. How much lost of soil would be detrimental to it survival? Thanks, Ralph
Hi Ralph,
I don’t have an answer for you on that problem. The plants do not have an extensive root system, however the weight of the root ball with soil could break the roots from the stem. If you can, get a tarp around the roots and lift/drag the plant by that, place in the hole, and slide the plant from the tarp. If a lot of roots are uncovered or broken, cut some of the foliage back. If it is going to be hot in your locality, I suggest a temporary cover with shade cloth, or a sheet/curtain. Keep the soil damp, not wet.
hi
we had two blackboys planted in Jan this year, one 3m plus and one 2m high, they are planted near each other in a V shape. The taller one is excellent, the smaller one’s foliage has gone dead but has some minor new green foliage in the middle. i cut back the dead foliage today and noticed that its quite moist in the middle and the foliage can be easily pulled out, what does this mean? the landscaper said to water 3-4times a week and on top to help hydrate it. What do you recommend? Is their rot in the top?
Thanks
Could you please let me know how to prune my grass tree or black boys as I’ve known them to be. I dont know what species they are.They were given to me as a gift.I have about 3. They must be at least 16-17 yrs old I’ve had them now for 14 yrs. Their trunk is short with lots of long grass like spikes all around. Can the grass be burnt and when do I do it so it looks like a black boy. The grass is very long and now they have their long spikes with seeds on them the birds love them. Please reply when convenient
Thanking you in anticipation ……….Wally
Hi there,
we were given a “blackboy as a present about two years ago, it is about a metre high and at the start the grass was sticking up and it looked really happy. It was in a spot in the shade and had the water from the drain dripping down onto it which it surprisingly seemed to love. We moved about 7 months ago and the day we moved the grass wilted and all of the new re growth does the same thing. On the grass there are tiny dark brown marks and after just having a good look there seems to be some kind of ants nest in there?
It is very dry and in a big pot and out of direct sunlight. Are all of these features normal as we have never had a “blackboy” before??
cant wait to hear back. Serenity
It sounds to me like a fungal condition in the root zone. Are there any ants in the nest? Any signs of other tiny creatures? If the soil is moist, hold off more watering until dry at 3-4 cm depth from the surface. Check that the soil in the pot has not become non-wetting. Soil wetting granules will solve that. Follow packet directions. Unless it is a species from a swampy area, grass trees need very good drainage. In a pot, the plant would need moisture, but it is possible to overwater. I would use a seaweed solution and water around the rootzone and over the leaves to try to stimulate more root growth. (Follow directions on the container.) Grass trees generally prefer open sunny conditions, but if the plant is stressed, keep it in a sheltered position, with good light and possibly some morning sun. If ants are present, treat them and find the origin of the ants’ nest. They will often take over a pot.
Great thank you so much. I couldn’t find any other little creatures and we have gotten rid of the ants and i cut back the grass. It looks 100% healthier now. We will do the granules and the seaweed solution.
thanks again
Serenity
I have about 50 Xanthorrhoea seedlings about 2 months old in pots. I wont be planting them in out for maybe 2 years, what are the do’s and don’ts of making sure they survive?
thanks
Gavin
he main thing to do is use deep pots, eg milk cartons with the bottom corners cut off for drainage. Be aware that they weaken with age, but if you have the plants in a box that will hold everything together until you are ready to plant out. You can plant them out sooner, and put a rock or stake beside each plant so that you keep track of them. You can buy long black plastic pots which have root trainers. They are about the size and shape of milk cartons.
Thank you Corinne, that sounds like excellent advice, when I plant them out would I take them out of the milk carton or leave it in and let the carton decompose naturally,
thanks a lot
Gavin
Tear the milk carton away, or up end, according to how tight the cartons feel. Even though they disintegrate, it takes a while and you really want the roots to establish and spread as quickly as possible to take advantage of available moisture.
I planted 4 grass tress this year and 3 of them now have sprung these big flower stems, which is growing very fast.
What is the normal maintenance required when these flowers appear – should it be cut back to the stem as it may attract pests ? or should I leave the flower as it is.
You are so lucky! How wonderful to have flowers stems forming. You have nothing to but watch this amazing thing unfold before you. The birds will visit the flowers when they form and open, and this is how pollination occurs. When the flowers finish you have a couple of choices: leave the flower stem as a curio for a while before you cut it off near the leaves, or cut it off as as soon as the flowers have finished. Sometimes you see a distorted flower stem and I believe that insect damage may cause this. However these are often seen as interesting variations when seen in the wild.
I WAS GIVEN A BLACK BOY,ABOUT A METRE TALL AND WITH A VERY THICK TRUNK, 2 SUMMERS AGO. 80% OF THE TRUNK IS BLACKENED, THE TOP 20% IS COVERED WITH THE STUBBLY ENDS OF DEAD LEAVES. IT’S STABLE IN A VERY BIG POT BUT HAS BEEN INSIDE THE WHOLE TIME AS ITS VERY WINDY HERE AND THE POT IS MUCH TOO HEAVY TO MOVE IN AND OUT AS THE SEASONS CHANGE. THE FIRST WINTER IT WAS IN AN UNHEATED ANNEX BUT LAST WINTER THE ANNEX WAS HEATED. IT’S BEE WATERED SOMEWHAT ERRATICALLY AS ADVICE SEEMS TO VARY FROM – THEY DON’T NEED MUCH/ANY WATER – TO – THEY NEED WATERING REGULARLY. IT’S NOT GROWN ANY NEW LEAVES SINCE I GOT IT. IN FACT, IT’S NOT DONE ANYTHING. ON ADVICE, A COUPLE OF MONTHS AGO I CUT OFF ALL THE REMAINING DEAD LEAVES AND GAVE IT A GOOD SOAK (ITS IN FREE-DRAINING COMPOST) ON THE GROUNDS THAT THIS MIGHT KICK IT INTO THINKING THE RAINS HAD COME, BUT STILL NOTHING. IT COULD BE MOVED INTO A VERY LIGHT BUT UNHEATED CONSERVATORY BUT HOW DO I KNOW WHETHER IT’S DEAD OR NOT?
It is possible that the plant is not dead. In a pot the rule is to check the moisture 3-4 cm below the surface. If it is dry, then water. The idea is to water thoroughly then check and water as needed. Plants in pots that dry out completely have no source of regaining moisture unless they are outside where it rains regularly. I would move it to where it gets a lot of light. They do not grow under trees in the wild, but need full light and sun. Water the pot with a seaweed solution to help stimulate new root growth, following directions on the container. Make sure the potting mix is actually getting wet when you water it as many potting mixes become water repelling when they are allowed to dry out. This causes water to run down the sides of the pot and not actually soak into the mix. If you find any soft or soggy spots on the stem or crown or around the base of the stem water with a fungicide. Other than species that grow naturally in swampy areas, grass trees are in general quite frost hardy, so should not need to be in a heated area. You should see some response as you move into your autumn.
Will my a Xanthorrhoea johnsonii regrow a flower? My tree grew a flower stalk last spring which was something special, but unfortunately i came home today and the stalk was broken of at the base.
If it will regrow a new stalk is there anything i need to do to promot the growth a of a new one?
A separate new flower stem will grow. The old ones are sometimes left because they can be decorative, but usually cut back.
Thankyou very much for the good news Corrine
If you are going to burn it it is the leaves that are burned. Burning is sometimes used to stimulate flowering. However, are you allowed to burn in your area? Quite frankly I don’t know how to do it. I would try a quick burn with the sole intention of tidying if it was possible to actually do the burning.
Hi
I have a blackboy that flowered this year. Very impressive. We want to tidy it up, do I burn the undergrowth of the blackboy to tidy it up. Do I burn the trunk / leaves ??? And if so how do I go about it?
Cheers
Zoe
We have a beautiful massive grass tree in our front yard. Unfortunately it appears to be dying. The skirt has turned very yellow and the top has black spots on it.
I’m wondering if this is normal due to a change is season or if it is indeed dying..? Any help at all would be great… It’s such s beautiful plant and I love it… I would hate to see it die
Thanks,
Emma
Do you have the green tufts of leaves at the top of the plant? If those have gone then I suggest that you kave lost the plant. If you have green leaves above the yellow there is still hope. Cut off the yellowed leaves. The black spots suggest fungal disease and an unthrifty plant. Try a fungicide (ask at garden centre) on the leaves, water the root zone with seaweed solution to stimulate root growth and check the drainage around the plant. It may have been too wet for too long. If your soil is heavy, poke a fork into the ground around the trunk and sprinkle with gypsum, 1 Kg to the square metre, and water into the holes. This assists with opening up the soil around the root zone.
You said “Xanthorrhoea preissii does not make a trunk, whereas the other does.”
Xanthorrhoea preissii most certainly DOES grow a substantial trunk up to 3 metres!
You are correct! I just checked my books and must have muddled them at the time of writing. Thanks for letting me know. I have edited the original post. My plant of X semiplana is beginning to take off. I raised it from seed years ago.
I have two mature grass trees about 2 metres high planted three years ago and gets most of the late morning sun.
We have clay soil and have removed the pots when we planted (a big no no according to many websites)
They was not much change for the for two years, then they produced their flower stalks but the never flowered, so I was told to cut them off to reduce any stress.
One tree has not produced any new leaves at all but the other has, and they seem to be browning on the ends of the foliage, in fact, each time I trim the older leaves back to halfway, they seem to brown again even futher up the foliage. Even the new leaves are beginning to brown on the ends.
I have treated them with Ground Breaker and Seasol in the past and have kept up their watering.
Can you please advise why this is happening and how can I improve their health – I dont want to lose them as they’re a great feature.
Are you perhaps over watering? At this time of the year they shouldn’t need very much unless you missed out on winter rains. My source suggests it may be beneficial to use a fungicide to drench the soil around the rootzone, then use a seaweed type product that promotes root growth. You may have fungal issues around the rootzone.
I obviously lost track of time with this. I hope you realised that it was ok to remove the old flower stalk. The stalks become interesting things on the plant, but you are probably better off cutting them off eventually so that the next flower stalk comes through without distortion. In the wild you find some old stalks on the ground, and some insect damage on the ones on the plant.