Eucalypts as bonsai: a summary of AusBonsai posts

Phil Rabl
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by Phil Rabl »

Yep, trimming promotes back budding. Most of the articles I have read about auxins and cytokinins talk about how trimming changes the flow of these hormones in the plant and induces axillary buds to shoot. Big variations between species, though. I find it interesting that burning the leaves of eucalypts triggers the same reaction in the tree as trimming, but like Peter I will stick to trimming. At least for now.
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by Phil Rabl »

In December 2021, a post asked about back budding and grafting eucalypts. (viewtopic.php?f=78&t=29961)

A very interesting response by Shibui said:

Backbudding
My experience has been that most stop making new buds when branches start growing strongly. Then almost all growth is at the tips which eventually leads to long, bare sections. Pruning at that stage is hit and miss - sometimes the branches will bud well, other times the whole branch dies back and new shoots grow from the trunk so everything needs to be started over. Most of the eucalypt growers I have talked to report they allow the eucalypt bonsai to grow slowly out with regular tip pruning but at some stage chop back hard and start over.

Grafting
Eucalypts can be grafted. Commercial grafted trees are available in nurseries, but I do not know the methods used. I recently tried some emergency grafting after a flowering gum in the garden broke off. Pretty sure none have survived. Approach grafting is a much surer method to get grafts. There's no reason it won't work for a eucalypt but I have had less success with low approach grafts because vigour is less lower down under the dominant canopy.

An experiment with breaking rather than cutting
I don’t have many eucalypts, but a few days ago I decided to try breaking a branch rather than cutting it back. I am assuming this will not change the likelihood of it backbudding. I did it mainly to try and mimic storm damage. I think the broken bit in the photo looks much more realistic than the old cut you can also see in the photo. Unless this technique proves to be a failure, I am going to break rather than cut branches on my eucalypts – only the branches that will stay as part of the design. Stray stuff that I don't want e.g., shooting from the lignotuber will be cut right back as normal.
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Phil Rabl
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by Phil Rabl »

There have been quite a few posts on eucalypts since I last updated this summary of Ausbonsai posts. A couple contain information that is worth adding to the summary.

Damaging cold temperatures

Sno reported in his post "How high can you go" (viewtopic.php?f=78&t=30784) mentioned that he protects his trees in winter because it can get down to minus 10 where he lives in the mountains. He said "I start to remove the stuff I am growing on gravel beds during autumn and if I think the top is too heavy I give it a trim to a growing point and try to leave as much growth as I think it can support. I can have frosts from now on, just light ones -1 or -2 s which help to shut down the trees".

In my experience in Canberra, the regular minus 5 frosts didn’t damage my eucalypts or banksia. The soil in the pot freezes rock solid, but the trees were fine. But minus 5 isn't minus 10.

Buying native nursery material - Root management

Rory’s post "Eucalyptus polyanthemos - Buying native nursery material" (viewtopic.php?f=78&t=30724) contains very useful information on root management.

"The most important thing to look for is the first root spread at the top. I very gently dig down around the base to see where the first roots are, and to see if it has a decent spray of roots coming out at the same area. This is where you can usually tell if it's been slip-potted from a young age. Often tubestock is left to become pot-bound before it's slip-potted into larger pots. You need to make sure that you can feel individual roots coming RIGHT OFF THE TRUNK, and not just roots that are circled around and around the trunk and then coming out radially."

See the post for more from Rory.
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Re: Eucalypts as bonsai: a summary of AusBonsai posts

Post by Sno »

Phil Rabl wrote: October 24th, 2023, 4:23 pm There have been quite a few posts on eucalypts since I last updated this summary of Ausbonsai posts. A couple contain information that is worth adding to the summary.

Damaging cold temperatures

Sno reported in his post "How high can you go" (viewtopic.php?f=78&t=30784) mentioned that he protects his trees in winter because it can get down to minus 10 where he lives in the mountains. He said "I start to remove the stuff I am growing on gravel beds during autumn and if I think the top is too heavy I give it a trim to a growing point and try to leave as much growth as I think it can support. I can have frosts from now on, just light ones -1 or -2 s which help to shut down the trees".

In my experience in Canberra, the regular minus 5 frosts didn’t damage my eucalypts or banksia. The soil in the pot freezes rock solid, but the trees were fine. But minus 5 isn't minus 10.
Hi Phil . Just to clarify . The tree mentioned in that post doesn’t get any winter protection . The winter protection mentioned in that post was about growing on gravel beds in general . I do have some varieties of Eucalyptus that I protect over winter ( Yellow box , Iron bark ) which are not as tolerant to my climate but E parvifolia quite happily lives here .
We are having a typical spring up here this year . It snowed last night , just a dusting (it’s Oct 26 ) which was lucky because it was a clear -3 morning . The dusting of snow helps insulate against frost . Spring frosts do more damage to a tree than winter frosts so a -3 today is harder than -10 in July .
The tree mentioned in that post is just starting to push new growth. I took a photo this morning .
6F90CB64-A21A-4AA1-89AF-6AF5A37706A2-30446-0000089F874B893E.jpeg
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