Gardeners of Australia

Dombeya collection

I think I first caught sight of a Dombeya tree in Barb Wickes' garden in Buderim - the Strawberry Snowball Tree (Dombeya cacuminum). It was massive with stunning scented flowers but made a hell of a mess due to its fallen leaves. Good news is however that was free mulch. It is a big tree and possibly too big for many gardens. I have not bought this species due to its high water need, but if I lived in an area with high rainfall I would have one.

A few years ago I came across the cane-like rambling species sold as Red Climbing Dombeya (D. ianthotricha). It is not a climber and is poorly marketed as that name. Its great when pruned back hard each year to produce upright stems from which the flowers hang. Its a good specimen for narrow gardens (provided it is pruned as explained) or used as a contrasting textural shape to surrounding low plants. Why I love this one is due to its red new growth, red hairs that cover all parts of the plant and gorgeous red bell flowers that are trimmed with golden pollen. Its tough... it handles drought well! This was my second Dombeya I saw in flower, and the second Dombeya I bought.

The first one I bought still causes me confusion. I suspect it is Dombeya pulchra with strong floral elements in that species. This plant is one of my favourites. It has become the screening specimen in my garden blocking views from and to the street. Like most Dombeyas the felt-like hairy leaves are delightful, but the soft pink-white flowers that are profuse in early winter are the winning feature, especially with the red eye to the flower. Bees love it (as with all Dombeya flowers).

I was on a role, I had to find more (and still seeking others). I tracked down Cape Wedding Flower (Dombeya tiliacea) which is used in South Africa as a tree or hedge, but here is best left as a single feature tree specimen. Good news is that it is not too big and has lovely heart-shaped leaves. Flowers are pure white and delicately scented.

[image by Noel Burdette]

My pride is the Mexican Rosetree - not from Mexico but from Madagascar (silly common name really). It is also called Pink Snowball tree which makes much more sense. The problem is identification of this species is extremely difficult due to a closely related hybrid - both have VERY similar characteristics making it difficult to tell them apart. Dombeya wallichii or D. x cayeuxii are similar in most ways and it is believed now that the specimen most people are growing is actually D. x cayeuxii, a hybrid. Unfortunately, most people sell this as D. wallichii.

What can I say about this plant that is bad, except that it keeps old flowers on the plant. This is a small tree to large shrub with massive leaves and gob-smacking awesome globular inflorescences. The flowers are scented - an added bonus.

There are more species - some trees and some small shrubs. There are not many available in Australia which is a shame as they can easily rival angel's trumpets, hydrangeas, camellias or flowering peach trees. The only disadvantages are that they flower mostly from early winter to early spring (if only it was longer), not much colour hybridising options available and they are not easy to propagation. As a result, they can be hard to track down and can be expensive - but worth every penny!

If you know of other species, please send me a personal message as I am on the HUNT :)

Check out issue 28 of subTropical Gardeningfor an indepth review of these plants...with more then to be featured in issue 29.

Tags: Dombeya, acutangular, cacuminum, cayeuxii, ianthotricha, pulchra, tiliacea, wallichii, x

Comment by Paul Plant on September 16, 2012 at 17:53: Another on my radar is Dombeya rotundifolia. Its a decent sized tree with dark fissured bark. In South Africa images show it in full bloom without any leaves however specimens in Brisbane Botanic Gardens at Mt Coot-tha are in full leaf when in flowers. This tree can rival any temperate blossom tree! From afar this tree appears blanketed in white flowers. Each flower is only small but are produced in clusters... many clusters.

Comment by Norma on September 24, 2012 at 7:45: Hi,

Just wondering if you have had much success propagating the Dombeya's? We've had Dombeya cacuminum growing in our garden for about 15yrs and I have not managed to propagate a single plant despite repeated attempts. But now we have to chop it down because it is shading our new solar panels and I desperately want to get at least 1 plant out of it before we do. We've tried taking cuttings at different times of the year and using different prop mixes and are presently trying aerial layering again. Any tips or secrets with propagating them?

Cheers,

Norma

Comment by Paul Plant on September 24, 2012 at 21:18: Hi Norma, I do not grow Dombeya cacuminum as it needs too much water for what I can provide (or should I say for what I am willing to provide). However, as the article in Issue 28 indicates, this is one of the species that does germinate well from seed. If tree has been removed, check the ground to see if you can find any seed capsules still unopen. As they are related to hibiscus plants, germination is similar - sow seeds in spring and seeds should pop up in a month or two. The shrub species are best propagated by layering.

Comment by Norma on September 25, 2012 at 9:56: Hi Paul,

Thanks for the advice but in all the years the Dombeya has been flowering I have never seen or found a seed capsule. The flowers are always covered in bees, native and European and all sorts of insects but it has never set seed. And as it has finished flowering I will have to try cuttings again but all my other efforts have failed and I just don't know what else to try. I have taken cuttings at different times, using different mixes and different types of cuttings and any technique I can find info on, including wounding and exclusion. We have a fairly good prop house and I can usually propagate most plants but this one is eluding me. Do you know if the gel the cuttings excrete affects root formation and if it does is there a way of mitgating it? Or is simply a case of really poor strike rates when it comes to this tree?

Cheers,

Norma

Comment by Paul Plant on September 25, 2012 at 10:40: Hi Norma

After speaking to some growers here in SEQ and online discussions with some USA folk, it seems that single specimens in gardens rarely set viable seed. In gardens where there are a few different specimens of the same species, seeds seems to be created and viable to germinate. However in other gardens where there is only one species (or specimen), the plants seems to produce no seed or sterile seed. I am testing that theory at my own garden where I have a number of different species, but none of the same. They appear to have seed but until they start to germinate I do not know if any will be viable or sterile.

I think with this big tree species, the best thing to do is track down another plant from a seller and buy it.

Comment by Network Creator on September 29, 2012 at 15:37: Hello Norma

I spoke to a grower on the Sunshine Coast. She said D. cacuminum is relatively easy to grow from cuttings but was not prepared to give 'trade secrets' away. Give it a go and you may be pleasantly surprised.

Comment by Paul Plant on September 29, 2012 at 15:40: Hi Folks.. if anyone else is growing these Dombeya plants and their specimen is different from what is shown above, please send me an email or upload the images... would love to track down more and feature them in future issue of subTropical Gardening magazine.

Comment by Jeannette Newton on November 1, 2012 at 7:58: I was interested to read that some of these plants require more water than others. Does this often happen with plants of the same species?

Comment by Network Creator on November 4, 2012 at 14:53: Within each genus, there will be different species that have different tolerances to a range of environmental situations.

Within the one species, different tolerances normally show up as a result of soil or other external stimuli. For example... Dombeya cacuminum grown in Eumundi in deep alluvial soil will look good most of year and rarely show water stress (Eumundi has a high natural rainfall level) whereas the same plant grown at Roma will likely be stressed if left to natural rainfall (rainfall is much less at Roma) and air is much less humid and frosts more likely in winter and water used will be borewater which is high is salts.

There are many variables that affect plant growth and no single guideline is correct for everyone. That's the fun of gardening - we all have different experiences and share those experiences.

Comment by Norma on February 27, 2013 at 14:32: Hi, Thought I would add my latest go at propagating the dombeya.

After Paul's comments about seed my husband spent hours hunting through the fallen flowers under our dombeya for any potential seed. We had never seen any seed capsules develop but in the end he found nearly 40 seeds, some were fresh and plump and some were a bit dried out. We planted them on 1st October 2012, we had one seed each germinate on 21/10; 22/10 and 9/11; the 1st two seeds were the fresh ones and the 3rd was from the seeds that were shrivelled. They are all doing well, have been potted up and are about 15cm high so far.

We did 10 more aerial layerings as well, but so far there is not sign of any roots. We did open one to have a look and it had just started to callous over and develop what looked like the beginnings of some roots so we decided to leave them and not be so impatient.

I also took 154 cuttings of various types on 1st October, 2012 and kept a record of how they all went. I took tip cuttings, heel cutting, hardwood, and even micro cuttings. Did wounded cuttings, I used propagation mix, sand only and prop mix with soil added from under the tree (suggested by a well known nurserywoman who has great success with natives). I took cuttings from last year's wood, this year's wood, some as thick as 15mm down to tiny 3mm thick, put some cuttings in the fridge overnight and I put some pots on gravel filled trays to increase humidity.

I checked them all daily for the first month, some died quickly, some were going great. By the end of December nearly every one of them was dead except 3 20cm long non-terminal branch cuttings and 1 micro terminal heel cutting 3mm thick. The 3 20cm long cuttings are growing new shoots, their bark is still firm but no roots are appearing in the weep holes, yet.

All the dead ones had failed to callous over. The last remaining micro cutting had developed a good callous but died when attacked by something in the prop house.

So I have got 3 seedlings doing really well, hopefully I can get them to the planting out stage.

9 aerial layerings we have to be patient with.

And I have 3 cuttings I am too scared to do anything to in case they drop dead.

We've put off cutting down the big dombeya, now that I have had this tiny, tiny success I want to try more cuttings at different times and treatments.

I am not letting this beat me,

Any suggestions about cutting time and treatment or where I could get more material from would be most welcome.

Cheers,

Norma

Dombeya collection

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