Eucalypts as bonsai: a summary of AusBonsai posts

Phil Rabl
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Eucalypts as bonsai: a summary of AusBonsai posts

Post by Phil Rabl »

The following information is a consolidation/summary of the many posts on the AusBonsai site on eucalypts as bonsai. My aim is to pull together a reasonably authoritative summary of what experienced practitioners know (and by implication what we don't know) about eucalypts as bonsai.

I developed the summary to use for an article in the Canberra Bonsai Society’s newsletter later this year. But I have decided to post this ‘raw’ version to AusBonsai so it can be accessed by a wider audience - and to get feedback, especially from those whose posts I have used. So, if you see anything you think is wrong, misleading or missing, please weigh in with a comment. I will revise my summary after I see what you all have to say.

Introduction

According to the Australian National Botanical Gardens, the term ‘eucalypt’ refers to three closely-related genera of the Myrtaceae family – Eucalyptus with 758 species, Corymbia with 93 species and Angophora with 10 species. It is not known how many of these are suitable for bonsai, but quite a few are being trained by bonsai artists right across Australia. Before naming them, however, let’s deal with the active debate on AusBonsai about whether eucalypts are worth the effort they take to train.

Some posts suggest eucalypts are unsuitable for bonsai and/or not worth the trouble because of their (generally) large leaf size, their habit of dying back as a result of trimming, their tendency to resent having their roots pruned, difficulty with ramification and the difficulty of producing a high-quality bonsai design. Posts in this camp point to the many other genera of Australian natives that are much better suited to bonsai, and some speculate that the Japanese would not have bothered with eucalypts if they were native to Japan.

Others point to the fact that there are many examples of beautiful eucalypt bonsai and encourage Australia’s bonsai artists to continue to experiment and learn more about them. They point out that the Japanese train only a selection of their native shrubs and trees as bonsai and when we have 800 years of accumulated knowledge about Australian natives as bonsai, we will be on a much more comparable platform with the Japanese than we are now. Not all Australian natives will prove to be suitable for bonsai, but until we experiment and learn we will not know which ones to avoid and which ones to use.

One experienced grower expressed amazement at some of the things said about growing gum trees as bonsai. Based on nearly 30 years experimenting with this group he has developed the following guidelines for training them:

1. Can be re-potted at any time but it is best done in Autumn. (Note that growers in colder regions recommend re-potting in the hotter months.)
2. Can remove at least 50% of roots provided that the soil remains wet for 3 weeks after re potting. Normal watering for the rest of the year.
3. Do not shorten new growth until it has matured somewhat. (new shoots tend to die back if pruned too soon).
4. Defoliation, regular shoot pruning and keeping in a smaller pot will over time reduce leaf size naturally.
5. Always remove any vertical shoots as soon as they appear.

See below for more information on the various techniques used by contributors to AusBonsai for training eucalypts as bonsai (and note that, as is usual, the advice is not entirely consistent).

Species suitable for bonsai

The following list (in alphabetical order) records species that contributors to AusBonsai say they have grown as bonsai (I may have missed some):

A. costata
• A. bakeri
• A. floribunda
• A. hispida

• C. citriodora
• C. ficifolia
• C. maculata

• E. botryoides
• E. bridgesiana
• E. calygona
• E. camaldulensis
• E. camphora
• E. crebra
• E. cinerea
• E. coccifera
• E. crenulata
• E. curtisii
• E. dalrympleana
• E. elata
• E. gunnii
• E. maculata
• E. mannifera
• E. melliodora
• E. nicholli
• E. orbifolia
• E. parramattensis
• E. pauciflora
• E. parvula
• E. polyanthamos
• E. pulchella
• E. punctata
• E. robusta
• E. rubida
• E. saligna
• E. sclephora
• E. scoparia
• E. sideroxylon
• E. spathulata
• E. stellulata
• E. tereticornis
• E. veronicas


I have heard Grant Bowie say on numerous occasions that with Banksia it is best to grow species that are native to your local area. Based on some comments on AusBonsai, this advice would appear to be valid for eucalypts.

Leaves

Eucalypts come in a variety of shapes, but the key issue discussed on AusBonsai is leaf size, including the capacity to reduce leaf size.

Naturally small leaves

According to posts on AusBonsai, species that have naturally small leaves include: E. archeri, E. bridgesiana, E. camaldulensis, E. crenulata, E. crebra, E. dalrympleana, E. eugenoides, E. nicholi E. parvula, E. punctate.

Reducing leaf size

As one post says, ‘nearly everything will reduce leaf size if you attempt it, but the starting point for the leaf size is huge for eucalyptus. If you can reduce the leaf size to about 8-10cm it can still look good on large bonsai.’ Several post also say that eucalypts usually look better grown as larger specimens because of the generally largish leaf size. Some, however, are training eucalypts as shohin.

A number of techniques for reducing leaf size have been posted to AusBonsai:

One post says: ‘To reduce the foliage size and get fine branching you can judiciously prune the large leaves, leaving the smaller leaves to supply the trees nourishment. This way the new growth will be much like the ficus regrowth after defoliation: i.e. smaller leaves.’

Another post reports removing 90% of E. punctata leaves, then again about 4 or 5 weeks later. The trees were only given about 1 hour of sunlight a day for the period. This second defoliation appears to keep the next sets of leaves permanently small. The post notes that from other trials, defoliating only once slows down the leaf growth, but about 4 weeks later they start to grow bigger.

And another: ‘If you keep eucalypts in smallish pots and reduce the growth back, in some circumstances you can keep the leaf size to about 4cm or so.’

Another has successfully maintained very small leaves on C. citriodora by pinching after the very first tiny leaflets come out. The grower lets it grow out towards the end of the season to get strength for the next season. A bonus is that the new shoots are often red, purple, yellow - bright interesting colours.

And another says: ‘I've found with the river red gums I can get very small leaves by continuously letting the shoots grow out to about 4 pairs then cutting back to the tiny fist pair of leaves. If the internode is too long to the first pair, cut it all off and wait for the replacement shoot. It's a lot of work though as you need to do this once a fortnight at least. Don't do this though until your framework is finished.’

Another post identifies some wider issues to be aware of as you attempt to reduce leaf size: ‘The main problem I had was trying to balance the feeding regime with leaf size and health. Being apically dominant most of the food was utilised by the new growing leaves which left some of the lower leaves decidedly yellowish. Too much fertiliser and the tree exploded with growth all over and good luck with keeping the leaves small and still most of the fertiliser was utilised by the top leaves!’

Posts on AusBonsai report successful reduction of leaf size on the following species: C. citriodora, C. maculata, C. ficifolia, E. archeri, E. bridgesiana, E. crebra, E. crenulata, E. eugenoides, E nicholi, E. punctata,

Defoliation

It is safe to defoliate eucalypts, but as always, follow the general advice about defoliation: ensure your tree is healthy and growing strongly; don’t defoliate in the same year the tree was re-potted; avoid fully defoliating a tree in the same year as a major prune; avoid fully defoliating immature trees. (Defoliating is a technique intended for 'finished' bonsai only; a tree intended for defoliation should have the trunk, primary, secondary and tertiary branches established. Defoliating a tree that requires branch or trunk building will slow down development of these parts greatly).

Probably the main reasons to defoliate a eucalypt are to reduce leaf size and to grow new, undamaged, leaves for the purpose of showing your tree.

When to defoliate

Advice about the appropriate timing for defoliation varies from region to region. As a general rule, however, you should not defoliate until the leaves have hardened off and there should be a good 6 weeks left in the growing season to allow the new leaves to mature.

Bark

Bonsai artists love bark. This includes those who grow eucalypts. Eucalypts grow a wide range of types of bark and there a quite a few photos on AusBonsai, some carrying captions such as ‘this is why I grow eucs’.

There is also some discussion, but no clear answer, as to the age can you expect to your eucalypt bonsai to produce adult bark. One grower says his E. Sideroxylon took 10 to 12 years grown on in a large pot. Another post commented that most eucalypts on display at a show had immature foliage because of constant trimming but that older branches were barking up. He has a 5-8-year old tree on which the bark is peeling.

Fertilising

Eucalypts are not prone to proteoid roots, so they should be fertilised normally.

Re-potting

Most experienced growers don’t re-pot and do heavy pruning in the same year. One post prompts us to remember that ‘many natives are developed by “slip potting”: just remove the entire root ball, keeping it as intact as possible (losing some mix does not usually cause problems) from the existing pot and place it into a new, larger pot then top up with the required amount of mix. Because it does not involve cutting roots you can slip pot any plant any time of year. A larger pot will usually result in increased rate of growth and development.’

When and how often to re-pot:

Growers in warmer climates indicate that it is safe to re-pot eucalypts at any time throughout the year.

Growers in colder climates unanimously recommend re-potting in the hotter months. One such grower says: ‘We have found that the best time for root pruning most natives is during the warmer months. I have been root pruning banksias, callistemon, leptospermum and eucalypts over the last month (the post was dated 26 November) and will do more before Christmas.’

One post says: ‘I re-pot the few eucalypts I have in late spring and early summer (November - December) when I do the rest of my native plants. I think they appreciate the warmer temps to help grow new roots.’

Another says: ‘The temperature in my area varies from -8 to +40 degrees C. I re-pot eucalypts from about mid-November through to mid-January and only every 2 to 3 growing seasons. Usually when temperature is between 25-30 degrees C. I avoid re-potting in autumn or early spring. I have found in early spring, as we come out of winter, the growth is slow and takes some time to recover roots and foliage. Autumn does not give them enough time to establish a strong root system and a good foliage cover which can stress the tree. When I have re-potted in autumn the leaves go purple over winter which is a sign of sap withdrawal and sometimes death. Most people are of the opinion that it is best to re-pot when the tree is dormant. I have found the opposite to be true.’

The same grower also recommends taking your cues from nature: ‘I take note of the flowering and bark-peel stages of the natural tree of the species I am training as bonsai and do my re-potting after flowering and I avoid re-potting or punning while the tree is going through its bark-peel stage.’

And another: ‘There should be no problem root pruning this in January. I also found that they rarely stop growing so in desperation I root pruned some in full growth and it did not hurt them. I believe the key is warmer weather, not dormancy for successful re-potting of eucalypts.’

How hard to root-prune:

Multiple posts on AusBonsai from growers experienced with eucalypts dispute the idea that they resent having their roots trimmed. This is not a unanimous view, however, as one grower with about 30 years of growing gum trees says it is not unusual for a gum tree to react adversely to root interference.

One post says: ‘I have been growing them in pots for over 30 years and have never lost one through root pruning! As long as you keep them wet for 3 weeks after root pruning, they will not only survive but will thrive in a pot. Outside this period regular watering only is required. This may seem counter intuitive but does work.’

Another says: ‘I have attempted literally 100's of eucalypts as tubestock starters. If you go too hard on the tap root initially and there isn't enough fibrous root, I find you can occasionally lose a few. As long as you have a decent amount of fibrous root, they will fare a lot better. However, once a eucalypt has a trunk diameter of about 1cm or more, it is very hard to kill it from root removal. But it can also depend heavily on the species you try. Some varieties can be very finicky when they are tubestock and you remove a lot of root.’

And another: ‘As with other species younger plants can be cut harder than older ones. I have taken 3/4 of the roots off some eucalypts with no ill effect. I know that others have taken all roots off E. camaldulensis just leaving the lignotuber and they have survived. Plants in forestry tubes will need more drastic root reduction than those in wider pots because it is usually hard to separate roots to get some horizontal roots in the tube seedlings. Trees in wider pots usually already have some lateral roots that can be left on.’

And another: ‘I have been growing gum trees as bonsai for more than 30 years. If long term success is sought it is essential that the roots do not dry out at all for 3 - 4 weeks after re-potting. If this technique is followed you can remove up to 50% of existing roots without a problem. Any taproot should be removed at the first root prune. NOTE: they do not like standing in water. This technique will ensure that the gum tree should thrive.’

And another: ‘Each species has slightly different needs. I have not root pruned E. ceasia but other eucalypts can be root pruned by more than half without upsetting them. How much you take off and how you do it will be dictated by what you find in that root ball. If there is only one long root coiled around you will need to consider what to do but I would still cut it, re-pot (and keep fingers crossed). I usually try to remove thicker roots and any vertical ones and leave laterals and feeder roots. I would definitely do a full tease out and prune so I can see what is there.’

And another: ‘I have cut back roots of several eucalypts quite hard - well over 1/2 of the root mass and most have coped very well during warmer weather. I've cut some back quite a lot more - 3/4 at least and most have survived the experience. Several times I've cut all roots and shoots back to the lignotuber and planted the lignotuber like a bulb - new roots and shoots follow quite quickly.’

Bare-rooting

Multiple posts from experienced growers indicate that eucalypts can be bare-rooted.

After-care:

The general rules for after-care apply to eucalypts, but a notable theme of AusBonsai posts is that a eucalypt must be well watered following a root-prune.

One post says: ‘In regard to larger stock, I have not had problems with root pruning gums. I have placed them right back in full sun, but just made sure the roots were kept well-watered and have not had problems either. I usually allow the tree to recover for about 3-6 months at least after a major root cut. It can take up to 4 weeks in some cases for the new shoots to appear after a root cut. Sometimes longer, so just be patient. With seedlings though, I just remove the tap root. I never let them get on the dry side after a root chop with seedlings. I always try to remove the tap root and leave a small amount of fibrous root on. But make sure you cut back the foliage if you remove a heap of the roots.’

Another post says: ‘Strange as it may seem for an Ozzie tree, gum trees roots need to remain wet for about 3 weeks after re-potting. Then back to normal watering and your tree will fire away.’

Many other posts make similar points about watering eucalypts well after re-potting.

Ground-growing

Eucalypts can be ground-grown to speed up their development. The general advice for these trees is to trunk chop them every year and to lift them and root-prune them every two years.

Heat/cold/sun/shade

Multiple posts note that eucalypts are adapted to grow in a wide range of climates, but species that grow in hotter climates will not necessarily do well in colder climates, and vice versa. Another reason to grow species that grow naturally in your area.

Pests and diseases

The main pests noted are: leaf-eaters (caterpillars, grasshoppers and fauna that seem to like to eat fresh young eucalyptus leaves but not mature leaves); mealy bug (strip some of the bark off so they don’t have anywhere to hide); myrtle rust; galls (usually caused by a wasp which lays larvae into the bark and they grow inside it creating a swelling. The holes are where the mature wasp emerges at the end of its metamorphosis).

Styles

Aside from discussion as to whether eucalypts are suitable for bonsai (see above), the weight of opinion is that eucalypts are best trained to look like trees in nature. The following comments give the flavour of these views:

One post says: ‘I love the many challenges of eucalypts. By combining bonsai and penjing I try to recreate what I consider a naturlistic style in eucalypts, as they don't look good as a Japanese pine.’

Another says: ‘There are wonderful majestic old trees out there, it's up to us to work out what we can build into in our work: large trunk/few leaves proportions, the large and strong dead branches, the constant movement in the branches, curious "clunky" angles, not graceful at all, but can make a tree with a lot of character.’

And another: ‘Hmmm. Tall slender elegant lonely eucalypt in the middle of nowhere, a few sparse branches, bark half shedding, the sound of crows in the distance....’

And another: ‘I'd love to see a nice multi-trunked mulga with spinifex like accents, with red topsoil or pot. Large red gums growing by a sandy bank on the River Murray are a favourite of mine with their exposed roots plunging into the river. Could this be recreated with an interesting pot? So many ideas...’

Tree development, trimming and pruning

There are several words of warning from experienced growers in relation to trimming and pruning: ‘it's damned hard not to fall back on your standard pine-and-juniper habits, but eucalypts don't grow that way’; and ‘if we are to strive for convincing looking AGED eucalypts as bonsai, wouldn't traditional bonsai techniques need to be used with caution?’

Trunk development

There is general agreement that you should develop the trunk first and then concentrate on branches.

As one post says: ‘You do want a separate trunk-growing phase. Really. The trunk is the core, the heart, the centre of gravity of the tree. It doesn't matter what you've done to the branches and leaves if there's nothing at the heart of it. My opinion only. For sure, grow, pinch and go crazy with whatever you want, but a tree that will live with you a long time needs a solid centre.’

Another post says: ‘Generally, re-pot in hot weather, water frequently afterwards, use a well-draining mix, and watch for leaf-eaters. I use general fertiliser, heaps of it, grow long, cut back once a year to get the trunk thick and interesting, and then face up to designing convincing branch shapes.’

And another: ‘Wiring the trunk is useless unless you are intending to keep the tree shohin or similar. You say you want the tree big, so thicken the trunk now. You will create movement on the trunk by trunk-chopping over time, not with wire. I recommend getting rid of the wire.’

And another: ‘They produce thick trunks quickly if (1) they are grown in a big pot and (2) they are allowed to grow freely until about 2 metre tall then reduced to (say) 30 cm then allowed to regrow to the 2 metres height and reduced again and so on until the desired trunk diameter is achieved. Correcting branching should wait until trunk diameter is finally achieved.’

And another: ‘I like cutting back hard because I get the chance to have angles and interest and strong trunks - it takes a while longer, but I like the result. There is certainly a place for long slender elegant eucalypts, particularly in Mallee forms, but unfortunately my mind just doesn't go there.’

And another: ‘By the time you have made two cuts to the trunk, with two resulting bends, you have pretty much defined the eventual size of the tree. If your first two cuts occur in the first 150mm of the trunk, the tree probably won't end up a metre tall - the low bends just won't be in proportion.’

Pruning

In the early stages, it is recommended that you prune once a year, and only allow two or three shoots to grow and rub off the rest. After a few years, when the trunk has developed some bulk and movement (see trunk development above) you are better placed to understand where you want branches to develop. This technique works for developing eucalypts because they bud back freely. For junipers, pines and leptospermum that don't bud back, you need to be more tactical - let one branch grow long and keep a couple at the base pinched short, and then cut out the long sacrifice branch after a year or so, and repeat the process at the next stage.

While you can expect your eucalypt to bud back after pruning, some posts report that back-budding can be variable.

One post says: ‘Pruning the tops is still a mystery to me. Sometimes they bud back all over, sometimes whole sections refuse to bud and die off. Maybe this is a time of year thing? On the plus side I don't think any have died completely after pruning. Some new buds always develop from somewhere.’

Be aware too that cutting back mature branches can lead to dieback in which case the tree needs a major cutback and rebuild. But as one post notes: ‘this is not so bad because the tree has grown in thickness and any thick dead branches can be used as jins.’

One post notes that, ‘like most trees, eucalypts try to grow to full height as quickly as possible. Pruning seems to be the best way to get branching lower on the trunks. Pinching the soft tips generally only results in the last 2 buds sprouting. You can let them grow quite large then cut back hard and they will sprout new buds from the trunk and base. Wiring for shape while still flexible is a great way forward. I put more bend than needed in young trunks because most trees thicken more inside the bends, so trunks get straighter as they thicken.’

Speaking mainly about his E. nicholii, one poster says: ‘I have had this E. nicholii for many years and as this tree has progressed it has taught me many things about eucalypts and in particular this variety. I have been unable to keep the height reduced with the pruning regime I have used over the past 16 years. So, observations of street pruning of eucalypts has shown that if pruned hard (cut back with no foliage) in the hot months (December and January), they produce new growth at and below the cuts. With this in mind I have done this to several of my eucalypts this year with success.’

Trimming

If you are wanting to mimic what one poster calls ‘the unique and incalculable branching characteristics of this native tree’ the usual techniques of regular clipping, constant pinching and wiring may not work with eucalypts. The same poster sates: ‘Deadwood, for instance, is an important feature on eucalypts. The undersides of branches often have dead limbs hanging downwards and, while you can recreate them by attaching dead sticks yourself, you may prefer to allow branches to grow until you are ready to create the deadwood.’

This is not to say that standard techniques of bonsai can't be used to capture a native tree. As another post says: ‘it's the forms we create with those techniques that determine whether we are successful or not, and gum trees respond well to root pruning and wiring.’

You can pinch the tip growth using tweezers so that you do it before the shoot extends too much. This way the internodes are close, and you get better ramification. But be aware that, as one experienced grower says, ‘generally, after soft growth pinching the tree will throw back 1 or 2 nodes with reduced leaf size. This causes creep over the years until it becomes too tall. I then have to cut the primary branches back and retrain the new growth. I think this can add to the look of the tree over time’.

Also, remember that, as another post says, ‘if you pinch a thin tree frequently it will stay thin, pretty much. It won't thicken slowly and naturally any time soon.’ Another post advises: ‘Do not cut back the stock until it is much bigger. Die-back usually occurs on eucalypts if you cut back the same area constantly (like more than once a month)’.

We are clearly still learning about how best to manage eucalypts as bonsai, as the following response of one grower to a question about tip pruning shows: ‘I'm still working this out. At the first stage, even before I dug it up, to get a rough branching structure I let it grow wildly and cut back into hard wood. Each cut would give a change in direction or a bifurcation depending on what I wanted. This gave me the bare bones. At this stage I am feeding (normal Osmocote) and constant tip pruning. I do this most days as I water. On the top two thirds of the tree I try take off the tip as soon as possible after the first two leaves open. For the crown I will do a couple of cycles of tip pruning and growing and then I cut back hard. This usually results in four buds and I select the weakest pair and start again. As I am still developing the structure of the lower branches and they are less vigorous I am letting them run for several pairs of leaves before pruning.’

Lignotuber

Quite a few posts mention lignotubers. As explained by the encyclopedia Britannica, an unusual feature seen in most species of Eucalyptus and some other members of Myrtaceae is the presence of lignotubers. These organs are large, woody, rounded outgrowths, up to several centimetres in diameter, surrounding the base of the young tree trunk. The lignotuber consists of a mass of vegetative buds and associated vascular tissue and contains substantial food reserves. If the top of a seedling, which has developed a lignotuber, is destroyed by fire, drought, or grazing, growth is vigorously renewed by the development of new shoots from the lignotuber. It is evident that this organ is of considerable value in an environment where fire and drought are frequent.

The following comments provide a summary of what posts say about lignotubers.

One post says: ‘I'll be rubbing off most of the buds soon, and keeping only a few to grow long, get fat, and build taper into the trunk. In particular, the lignotuber shoots must be rubbed off, as they will take over, and you will lose the top of the tree.’

Another says: ‘When replanting after root prune, just ensure you replant at the exact height in which the nursery sold it to you. The lignotuber is between the trunk and the roots. It needs to stay just above ground level.’

And another: ‘There are many, many shoots growing from the lignotuber - they have to go, as the top will die if they are allowed to grow.’

Ramification

Numerous posts indicate that there are challenges to face in getting good ramification on eucalypts.

Some do not value in eucalypts. One says: ‘All that detail in the movement of the branches which can be achieved on a maple or an elm or just about anything, cannot be achieved on eucalypts. It can't be done by wiring, only with scissors and time, and gums just won't accept cutting and growing like that. Or, perhaps there is a technique which has not been worked out yet?? If it can be achieved, I would like to see it! Maybe someone slavishly working in his backyard will have something to look at in the coming few decades?’

On the other hand, another believes it all boils down to species selection. He says he is confident he can get natural movement and ramification using many of the gums that he is growing, but acknowledges that it can take many years, partly because cutting back a gum branch outside he period mid-spring to late summer carries a big risk of die-back. Some gums that he has trunk-chopped have died back right to the base, but he says with time and experience you develop an understanding of which species are better to pursue and which ones are better left alone.

Wiring

There is general agreement that you can apply wire to eucalypts.

One post says: ‘I've had no problems wiring as long as I kept a close eye on any strong upward growth on the wired branch. Another says: The tree is very pliable and sets to shape well when wired.’

Others offer caution: ‘Be cautious with wiring the weaker branches until they have more foliage; don't let the wire bite into the bark, it can take years to lose the wire marks; if you do wire small branches, you can cage-wire them (loose wiring) to get some shape into them but you need to do it early, and not for long. They harden off, thicken and scar quickly.’

Some say it is a waste of time wiring a trunk, but one post says: ‘wire the trunk straight away but also choose and wire the primary branches as soon as possible. In nature, gums have massive branches that almost match the width of the trunk, so you want them in place and growing quickly. In my observations even branches that extend below the horizontal still start off leaving the trunk close to the vertical so wire accordingly.’

Propagation

Eucalypts are notoriously difficult to strike as cuttings, so they are nearly always grown from seed. If you are going to collect seed, you need to be able to identify ripe seed capsules and understand seed germination techniques.

As explained by one experienced grower, ‘normally when the seed is ripe the capsules open on the tree and drop the seed. Much later the spent capsules fall but by then they are almost always empty. In my experience any seed that is left after initial seed drop is very unlikely to be viable. I have found this with many species including exotics like pine. To get good seed you need to target unopened seed pods, but I understand the problems with very tall trees. Best opportunity to collect is when the wind has picked a branch or two for you and dropped it on the ground. Also, sometimes after the cockatoos have been there will be small branches of ripe pods on the ground. You need to be quick though. Seed capsules open and spill the seed as they dry out, usually a couple of days after they are cut off the tree. A lot of seed is actually viable for some time before it naturally drops, and some species retain ripe seed for a year or more before dropping it so you can collect good seed for a large part of the year rather than just when it is dropping.’

If you are thinking of layering a eucalypt, be aware that you will have to be very patient. One post advises that ‘they will take a long time, so you need to check if the layer is drying out.’

If you are planning on collecting a tree, be aware that the roots may be long and deep and you may not have surface roots to keep it going. If you want to be more certain do some work on it first. One post says: ‘I would cut around it with a shovel, cutting heavy roots and then replace some of the dirt with your bonsai mix. Leave it for a few months then if there are new roots growing in the mix dig it’. Opinions as to when is the best time to do a dig vary: some say autumn; other say the warmer months. There is general agreement, however, that you should put it into as free-draining mix as you can get, and water it frequently (2-4 times a day) afterwards. Some growers have succeeded, others have failed.
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by greg27 »

Thanks for posting this Phil, some excellent info there. I'm trying to set a bit of direction for myself rather than getting excited and grabbing every type of tree that I can, and eucalypts will be a big part of my focus.

So far my collection includes E. victrix, camaldulensis, nicholii, calycogona, largiflorens, leucoxylon and tetraptera - all tubestock except the victrix so nothing advanced yet. All have undergone a bare root and root prune (~50%) and have lived to tell the tale, and all have backbudded except the tetraptera.

I'm hoping to get my hands on a few other species soon that aren't on your list.

Matt S has very successfully reduced the leaf size on E. camaldulensis: https://www.ausbonsai.com.au/forum/view ... =6&t=27087

Hopefully as things progress I can help provide some extra info.
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Post by Keels »

Awesome work consolidating this info into a great thread. Just getting into gums myself so this will definitely help.
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Post by MJL »

Thank You Phil. :clap: :yes: :beer: :tu:
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Post by Matt S »

Thanks Phil. A lot of work has gone into this and it’s much appreciated. Especially if it means more Gums!

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Post by GavinG »

Thanks for your work Phil. A few personal opinions:

Small-leafed Eucs such as E. crenulata, E. bridgesiana and E. parvifolia tend to be less apically dominant for me, and can be cut back and pinched reasonably frequently without die-back. They also do not need defoliation. You do need to leave more foliage on all natives through our hard winters in Canberra. These species are hardy and strong growers here. Should be compulsory. Longer-leaved Eucs such as nicholii, scoparia, viminalis, elata and punctata tend to be more apical and more problematic with cutting back, but can still make good bonsai. For me, there is no need to grow large-leafed Eucs like A. costata and E. sideoxylon, in the same way we don't usually grow Pinus mexicana or Acer negundo.

(Small plug) Anyone attending the Australian Plants as Bonsai symposium in Canberra on Feb 29- March 1 will see maybe ten Euc trunks I've been developing - I'm giving a talk on trunks.

I do repot every year, and prune hard at the same time, but my trees are all younger than 10 years, and growing strongly - a 30 year old tree may be quite different. I also root-prune in the middle of bark-peel with no problems.

After repotting I put trees in a water bath that evaporates every day to dry, so plenty of water but not water-logged. It is amazing how much water they will get through in full growth - twice as much as similar exotics. No water bath through the summer unless it's viciously hot, because the growth gets too leggy.

I have had major problems digging trees up after ground growing for only one year, and would not recommend it. One or two roots become thick and dominant, and won’t survive the cut. Possibly frequent heavy watering in the ground would keep roots close to the surface, but that's not what happens here.

I repeat, this is just stuff that works for me.

Thanks again Phil,

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Post by Rory »

Yep, I have found the same as Gav with ground growing Eucs.
I no longer grow them in the ground. The tap roots go like a jack hammer into the ground and the radial roots will suffer as a result. (In fact, a lot of other genus will suffer this problem too, and I’ve actually stopped ground growing altogether).
Then when you cut the tap roots and pull it out of the ground, the immediate radial roots aren’t vigorous enough to sustain the tree, and I’ve lost many Eucs from this.

Also, I note that a few members have mentioned not to allow the growth from the lignotuber to flourish or you lose the upper structure?
I have never found this happens. I’ve grown probably about 30 different types of Eucs and I’ve never once seen this happen.
My belief would be, that those members may have cut back the upper structure out of the strong growing season perhaps, and it’s died back as a coincidence, but not because you’ve allowed growth from the lignotuber to grow. Alternatively there could be any number of reasons the tree would die back, but I strongly doubt it is from allowing a lignotuber to shoot unhindered.
The lignotuber basically allows the Euc to become multi-trunked, which you see all the time in the wild and it’s beautiful.
It supposedly acts as stored energy after trauma or a fire, but regardless, it still shoots from here as they grow.

I always encourage my Eucs to shoot from the lignotuber as I found it looks so natural and very Euc-like. But never has it compromised or been detrimental to the upper structure of a gum.
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Post by Keels »

I was at cool natives nursery this arvo and found this thread as a great resource when shopping for potential gums that I could use for bonsai since they were out of red River gums.

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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by Phil Rabl »

Thanks for your responses, folks. Please keep them coming. This is how we learn from each other.

I have been thinking about the contradictory advice about wiring the trunk of a eucalypt and have decided there is a difference between trees being grown with a single trunk (the advice here seems to be pretty unanimous that growing and cutting is the way to go rather than wiring); and trees being grown as a multi-trunk design. In this case the tree appears to benefit from having the young branches (trunks) wired into shape and then allowed to grow freely before being cut back and grown again. This is what I am doing with my multi-trunk eucalypts and it all looks good so far.
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Post by MJL »

Phil Rabl wrote:Thanks for your responses, folks. Please keep them coming. This is how we learn from each other.

....and trees being grown as a multi-trunk design. In this case the tree appears to benefit from having the young branches (trunks) wired into shape and then allowed to grow freely before being cut back and grown again. This is what I am doing with my multi-trunk eucalypts and it all looks good so far.

I am taking this approach too... and touch wood, pardon the pun - it seems to be going ok. Image


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Post by LLK »

This post surely deserves a BUMP ? :bump:
Great article, Phil! Makes interesting reading and deserves more attention.

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Post by Phil Rabl »

Thank you to those who have commented on my summary of AusBonsai posts on eucalypts as bonsai. I am at a very advanced stage with turning the summary (modified by comments posted) into an article for the Canberra Bonsai Society newsletter and would appreciate it if anyone else who has a comment in their mind could post it asap so can have the benefit of it in finalising the article.
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by greg27 »

Hi Phil, something that might be worth adding to your article: in Bonsai with Australian Native Plants by Dorothy & Vita Koreshoff they include the warning that the roots, trunk and lignotuber should never be planted deeper than the original soil level. Exposing more lignotuber/root is fine, but burying more will lead to death of the tree. I have no experience to back this up personally, but in the book the preface the warning with "UNDER NO CIRCUMSTANCES" in caps so it sounds serious to me!
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by shibui »

Vita wrote that book at a time when very little was known about Aussie natives as bonsai. It was groundbreaking and has helped many of us get into the fascinating world of Australian bonsai. As time has passed we have found that a number of the things Vita wrote are not quite accurate. 'Never plant a Euc lower than it was' has turned out to be one of those innacuracies though it was widely believed in hort circles at the time it has turned out to be an urban myth.

Eucs and other natives are now routinely planted out deeper by landcare groups, landholders and bush regeneration teams. Having the roots deeper seems to give a far better survival rate over the first summer as the tree has access to slightly deeper moisture in the soil profile. Most species just grow new roots from the buried trunk.

If you consider this from an evolutionary survival strategy it makes some sense. Species that live on floodplains live with shifting soil levels as floods deposit or remove layers of soil. If those plants could not tolerate changes to soil level so many would die after each flood that the species would have become extinct millennia ago.

Planting a lignotuber deeper or shallower will not kill or even harm any of the Euc species I have worked with and probably none of the others.
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by greg27 »

shibui wrote: March 22nd, 2020, 7:20 am Planting a lignotuber deeper or shallower will not kill or even harm any of the Euc species I have worked with and probably none of the others.
Thanks, I'll take what's in the book as advice rather than gospel!
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