Howdy folks!

Recently on another Forum, somebody asked for tips and pics pertaining to Eucalyptus Bonsai, so I set about trying to compile a bit of info for him. Searching the Net, I found very little useful information on the topic, and an awful lot of misinformation. So, I thought I'd try my hand at creating a "Eucalyptus Bonsai Primer". Bear in mind that this is a work in progress - as are the Eucs in my possession . Anyway, what follows is based on fairly extensive research as well as my own observations. Where possible, I will try to differentiate between fact and opinion.

Please feel free to add comments, correct me if I'm wrong, and ask questions.

Thanks.

FlyBri.

PS: I'll be posting this in several sections.

PPS: Seems the footnotes I used in Word do not translate here. Where possible, I will provide links and/or references.

Eucalyptus as Bonsai.

According to ASGAP*, the genus Eucalyptus includes around 700 species, and the closely related genera Angophora and Corymbia include over 100 species. Thus, my attempt to compile hints and tips for training Eucs as Bonsai will tend to be quite broad and general, though I will deal with specifics where possible. I currently have about ten Eucs (and Angophora) in various stages of Bonsai training, including E. camaldulensis, E. meliodora and A. costata. I have also killed about the same number of Eucs, including E. radiata, E. citriodora, E. macrorhyncha and A. floribunda (I like to think that I am learning from my mistakes…).

Material

When choosing Eucalyptus specimens for Bonsai culture, there are a few considerations to be made which do not necessarily apply to more traditional species. I have found that Eucs already adapted to pot culture (IE: untrained nursery stock) are preferable to collected specimens, in that their root systems are quite compact, and rarely have a strong tap root. Trees collected from the wild tend to have expansive, sparse root systems which can prove difficult to dig up intact. That said, many Eucs can be collected with little or no roots, so long as all leaves are removed and the tree has a sufficiently large lignotuber (see below) to allow it to rebuild a root system. Personally, I would rather start with an established root system, unless the tree to be collected is of exceptional quality.

Many Eucs grow lignotubers at or near the surface of the soil. These swollen, woody nodes of undifferentiated tissue act as reservoirs for food and water, and allow a tree to regenerate after fire and drought. While some lignotubers will add bulk and character to a Euc’s trunk, many will simply swell above the root system, causing ugly and irreversible reverse taper. Thus, in choosing a Euc for Bonsai, it is important to know what is going on just below the soil line – if you can, try pushing some of the soil away from the trunk (if the nursery folks become agitated, just assure them that Eucs can handle having their surface roots exposed). From my observations, branches and foliage which emerge from a lignotuber will serve to make the tuber even larger, so it is often desirable to remove such branches. In short, it is wise to ensure that any lignotuber present will enhance the design of the tree.

Vita and Dorothy Koreshoff suggest E. saligna (Sydney Blue Gum), E. nicholii (Willow Leaf Peppermint), E. maculata (Spotted Gum) and E. sideroxylon (Pink Flowering Ironbark)**. I have had temporary success with E. radiata (Narrow Leaf Peppermint), E. citriodora (Lemon Scented Gum), E. macrorhyncha (Red Stringybark) and A. floribunda (Rough Barked Apple). The trees which continue to survive the punishment I dish out are E. camaldulensis (River Red Gum), E. meliodora (Yellow Box) and A. costata (Smooth Barked Apple).

Of the Eucs I have, one has been trained from a seedling, one has come from an air-layer, and the rest have been chopped down from cheap, root bound nursery stock. An added advantage of buying such neglected nursery stock is that these specimens are often ready to be root-pruned and repotted straight away, as their condition will simulate dormancy (see ‘Repotting’, below).

Finally, leaf size and internodal spacing should be considered when choosing Eucalypt material for Bonsai. In my experience, Euc leaves will reduce with constant pinching, and internodal spacing likewise. However, leaf reduction appears to come at the expense of mature foliage: many Eucs display both mature and juvenile leaves, and the latter can differ quite significantly from the former. As with other broad-leafed species, the size of the leaves should be matched to the overall design of the tree.

Eucalyptus species generally grow quickly from seed, and many can be struck from cuttings or air-layers, providing the material chosen still has immature bark.

*http://farrer.riv.csu.edu.au/ASGAP/eucalypt.html

** 'Bonsai With Australian Native Plants', Dorothy & Vita Koreshoff, Boolarong Publications.

__________________
Australian Native Plants as Bonsai Study Group
ANPB Galleries
---
rrr.org.au - Support Free-Range Radio

Gday folks and Merry Xmas!

Sorry about the delay in getting this 2nd installation up, but it's been a busy time of year... Anyway, here's part 2. Please feel free 2 comment or ask questions.

Thanks.

FlyBri.



Root-Pruning and Repotting

There are a number of myths surrounding the ‘untouchable’ nature of Eucalypt roots – many folks believing that root-pruning a Euc will cause certain death. While this can be the case, especially with collected specimens, it is my experience that correct root-pruning techniques will more often than not produce happy, healthy potted Eucs. The main factors involved in ‘correct’ root-pruning are choice of material (see Material, above) and timing.

As with deciduous trees, Eucalypts are best repotted during dormancy, but as Eucs are evergreen, it is a little more difficult to determine when that is. Given enough water and light, Eucalypts will generally grow all year round. In nature, Eucs will tend to experience dormancy in late-summer, as this is often the driest time of year. During this time, there will be no new growth at the tips of branches, and all leaves will have hardened off.

There are a number of ways in which dormancy can be induced or simulated. The most natural way – and also the riskiest way, in my experience - is to show a Euc a little careful neglect, allowing it to gradually dry to the point where it experiences dormancy. (I have killed a couple of Eucs this way, and don’t recommend this method – it is simply too hard to tell precisely how much neglect is too much.) Eucalypts which are root-bound will also become dormant, but allowing a tree to reach such a condition can be hazardous. The safest and easiest method I have come across is to simulate dormancy by removing foliage from a Euc, since we are defining ‘dormancy’ as meaning that there is no new growth on a tree. The Koreshoffs recommend the removal of all foliage from a Euc which is to be repotted, either by singeing over a fire or by simply trimming with shears. This would be my suggestion when collecting Eucs from the wild, but I have found it unnecessary when dealing with specimens which are already adapted to container culture. I have had great success by simply cutting all branches back to one set of mature, hardened leaves during repotting, but this is entirely dependant on the health and volume of the roots that are to be pruned. For the inexperienced, I would suggest complete defoliation.

Another area of conjecture is the amount of roots which may be safely removed. The Koreshoffs talk of ‘severe’ root-pruning and ‘bare rooting or removing the outer section of the root ball only’. However, they do not speak in terms of the proportion of roots which may be removed. As a rule of thumb, I tend to go with the Bonsai standard of removing ⅓ to ½ of the existing roots, cutting out any strong tap roots. In cases where there is a large lignotuber present to sustain the tree during the trauma of repotting, I have successfully removed as much as ⅔ of the root mass.


It is commonly believed that a Eucalypt should never be repotted deeper than the previous soil level, for fear of the certain death of the tree. This is not something I care to challenge (though I do suspect that a young Euc would be more tolerant of deeper repotting than would a more mature tree). Eucs will happily withstand having surface roots exposed.

Howdy all!

As promised earlier, I am putting together a pictorial guide 2 the root-pruning of an Angophora costata (Smooth-Bark Apple) I picked up recently for $30 from a local general nursery. (While not a true Eucalyptus species, Angophora is so closely related in habit and form as 2 be included under the title 'Eucalypt'.) One of the main features of this species is the smooth bark which flakes off on a yearly basis, giving a brilliant multi-coloured display similar 2 that of Lagerstroemia species. As the size of mature leaves can be quite large, this specimen is destined 2 be a larger Bonsai - I imagine that 60cm (2') would be a good height 2 aim 4. That said, Euc leaves will reduce with constant pinching.

The tree in question was in a 30cm (12") pot, and was about 60cm tall from the soil line. I have chosen this specimen 4 its unusually dramatic trunk taper - I am unsure whether this habit is genetic or cultural, but most of its brethren were at least twice the height (and general girth) at the same age. The fact that the enormous lignotuber is sprouting numerous branches indicates that this specimen will have no problems in backbudding.

Attached Images

RIMG1933271204.jpg (58.2 KB, 815 views)

Here is the tree in question with the soil cleared away from the trunk. U can see that I have exposed the part of the lignotuber which begins 2 taper back inward. In order 2 avoid reverse taper here, I have made a note of the original soil level so that the tree may be repotted 2 its original depth (or a little shallower). As the lignotuber is undifferentiated tissue, I am hoping 4 roots 2 fill in the area around the base - the tree may not wish 2 co-operate...

Attached Images

	RIMG1935271204.jpg (70.9 KB, 505 views)
	RIMG1937271204.jpg (72.7 KB, 441 views)

Next is a view of the rootball as it came out of the pot. Sorta hard 2 tell from the pic, but this tree was well on the way 2 becoming root-bound (note that in the very 1st pic, there is no new growth present). So, out came my new favourite Bonsai tool - a razor-sharp machete! Within a couple of minutes, I had hacked off the root collar at the base, which included a handful of finger-thick roots. The amount of roots initially removed was about ¼ of the overall mass.

Attached Images

	RIMG1939271204.jpg (62.3 KB, 293 views)
	RIMG1941271204.jpg (61.0 KB, 282 views)

Here is the little fella minus about ⅔ of his roots - as mentioned above in the 'Root-Pruning and Repotting' section, I reckoned that the bulk of this trunk/lignotuber was such that I could remove more than half the roots safely. I've given the roots a rinse, and done a little gentle untangling 2 try 2 create the beginnings of a Nebari - though such an impressive trunk flare might not need surface roots. Note that at this stage, I still have not removed any foliage - now that I've had a chance 2 survey the root system, all branches are cut back to the 1st set of leaves.

Attached Images

RIMG1944web.jpg (57.1 KB, 267 views)

The Angophora needs 2 go into a training pot for a couple of years in order 2 develop bulk and branches. The pot here is the same size as the one it came in, and I've inverted an old Osmocote bucket so that the roots which grow will be more manageable at the next repot. The gravel at the base is there 2 prevent the soil falling thru the drainage holes. The soil mix consists of about 60% sifted potting mix (from the original rootball, as well as some additional proprietary mix) and 40% sharp gravel (in this case, it is basalt (bluemetal) sifted to ¼"). Many would question the wisdom of recycling soil the tree came in, but I am a firm believer in maintaining the original soil bacteria etc, especially if the tree is already in good health. I have been wrong before...

Attached Images

	RIMG1949web.jpg (71.6 KB, 201 views)
	RIMG1952web.jpg (71.5 KB, 176 views)

FlyBri,

these are very good posts. Here is a picture of a gum tree that won best of show in the Australian Convention in Canberra this April. I like it very much for looking more like a gum tree than like a 'bonsai'.

Attached Images

Dscn7381v.jpg (61.7 KB, 898 views)

Gday Walter!

Thanks 4 taking the time 2 comment - I imagine U are a very busy man.

BTW, do U have the details of this tree? Specifically, I'd like 2 know its species, size and the name of its trainer - so far nobody else has spoken up about Eucalyptus as Bonsai, although there are obviously people out there doing it convincingly. I would like their input, if at all possible - after all, I've only been doing this since about 1997, and I'm sure there are many points I have missed or gotten wrong.

Thanks again.

FlyBri.

PS: I hope 2 have some trees 4 U 2 look at in 'Ask the Master' some time in the next 20 years.

And here it is this morning, exactly one month later. U can see where I have cut all the little 'branchlets' back to the 1st set of leaves, as well as the complete removal of the 'canopy' - all of which took place just after the repot. Note the crimson new growth which is appearing at almost every node and bump on the trunk. I will let these grow unhindered until it is time 2 choose new branches, being careful not 2 let any stay on long enough 2 create ugly bulges.

I have placed a thick (15-20mm) layer of gravel over the soil 2 act as mulch, as well as 2 hold the soil in place.

I am still unsure as 2 the final direction of this tree - I need 2 thin out some of the less attractive growth and let the thing recover 4 a while. I am leaning towards a multi-trunked Mallee-style tree, as seen in many of the drier areas of Australia, but we'll see which direction the little Angophora wishes 2 take...

I'll keep y'all posted.

Thanks.

FlyBri.

PS: Thanks Matt for merging the 2 original bits of text into 1.

Attached Images

	RIMG1983web.jpg (59.9 KB, 300 views)
	RIMG1986web.jpg (71.6 KB, 299 views)