Hokkaido Elm Care

[badatusernames]

WELLLLLLP

You've either opened this thread unawares, or you know this species and are getting ready for the typical questions. So let's just dive in, because the best advice for Hokkaido Elm appears to be "don't do it", but that advice would only have been useful to me a year ago when I was sure that whatever "difficult species" meant was something I could overcome. I do see another thread on the subject was bumped recently, but I didn't see what I was looking for there so thought I'd start this one for mine.

Here's the tree.



So, I knew going into it that the branches break like pretzel sticks. Wiring is virtually impossible. But clip and grow on a tree of this size? Seems reasonable.

As you can see, however, it leafed out improperly, or not quite vigorously, or late, or something. Leaves aren't where they're supposed to be and there aren't really as many as I'd like.

On TOP of that, the branch in the back is real bad off:





It's not completely dead, as you can see by the new growth, but all that ramification, all those branches above that new growth? Probably gone, based on what I've read on the species.

When I try to find information, I mostly find information about Chinese elm with an aside for Hokkaido elm. When I find Hokkaido elm specific information, it's typically people imploring others not to waste their time with the species. However, I did hear via word of mouth that there may be an element of controlling growth in spring that resulted in what we see here: all the energy going to the main two tallest branches of that trunk, and virtually none going to the third, shorter, smaller one in the rear.

Does anyone know the trick for these? I'd love to keep messing with it even if it's a dead end, because frankly I still find it quite beautiful. It may never be perfect, but I think making it enjoyable to look at might be achievable if one keeps on top of the growth.

 

[Bonsai Nut]

When's the last time it was repotted? I would start with the roots and assume that is at least part of your problem.

Also, like standard Chinese elm, in order to maintain tight ramification you need to balance strength. In the spring, if you don't pinch long growth, the tree may suffer die-back of the weaker branches and start to become leggy. Do not be afraid to pinch or defoliate the tree as long as it is strong. Good news is that it back-buds easily, so you can rebuild ramification quickly if you let the tree run a little too long without maintenance pruning.

 

[badatusernames]

When's the last time it was repotted? I would start with the roots and assume that is at least part of your problem.

Also, like standard Chinese elm, in order to maintain tight ramification you need to balance strength. In the spring, if you don't pinch long growth, the tree may suffer die-back of the weaker branches and start to become leggy. Do not be afraid to pinch or defoliate the tree as long as it is strong. Good news is that it back-buds easily, so you can rebuild ramification quickly if you let the tree run a little too long without maintenance pruning.

That's super helpful, thank you. It was late to come out, and when it came out it was weak, so I didn't want to do much to it. It was repotted this year but we did not work the roots hard.

I wonder too if this pot should be deeper, perhaps.

 

[Bonsai Nut]

Here's a little clump style one that I've been messing around with as an experiment - trying to see how fast I can get it to grow. I have it planted in a 1 gallon nursery container in a pine bark mix which I did simply to try to get it to throw long roots in the container. In the spring I will replant it into a wider container and spread the roots out wide.

 

[Shibui]

You have found some of Hokkaido's weaknesses. Brittle and prone to die back both expected and unexpected.
I've also found that these are very apical dominant so lower branches are prone to die if the apex is allowed to grow strongly. The reasoning should also suggest an answer - more pruning. They can be pruned as hard as you like and will still respond with lots of shoots.
There could also be an element of care in the amount of dead yours has as mine do not usually die back that much. Water is critical in such small pots. I repot most of my smaller bonsai annually as pots are so full of roots after just a single year that watering becomes really difficult trough the second summer and decline is the usual outcome. that pot is also very shallow which will contribute even more to tree health problems. i have moved away from really shallow pots now and get better results.

The long, straight sections on both trunks are typical of Hokkaido but not attractive. Chop much harder. Pruning won't hurt the tree but will vastly improve the structure.

 

[badatusernames]

You have found some of Hokkaido's weaknesses. Brittle and prone to die back both expected and unexpected.
I've also found that these are very apical dominant so lower branches are prone to die if the apex is allowed to grow strongly. The reasoning should also suggest an answer - more pruning. They can be pruned as hard as you like and will still respond with lots of shoots.
There could also be an element of care in the amount of dead yours has as mine do not usually die back that much. Water is critical in such small pots. I repot most of my smaller bonsai annually as pots are so full of roots after just a single year that watering becomes really difficult trough the second summer and decline is the usual outcome. that pot is also very shallow which will contribute even more to tree health problems. i have moved away from really shallow pots now and get better results.

The long, straight sections on both trunks are typical of Hokkaido but not attractive. Chop much harder. Pruning won't hurt the tree but will vastly improve the structure.

I was wondering about that too. Maybe next year i transfer to a grow pot and chop it hard in spring

 

[Si Nguyen]

I second what Shibui said. Hokkaido's have very weak root system. The roots are very small and do not ramify much. The roots are very sensitive to die back, from being too wet or too dry or too much or too little fertilizers, unlike the common Chinese elms, and that's why you see sudden dead branches above. This root system weakness is similar to many other dwarfed species of trees and plants. I have killed a few of these elms. They are just so finicky. The ones that lasted the longest for me were grown in clean akadama and in slightly deeper containers. In shallow trays, the surface roots dry out too much in direct sunlight in the summer, but a nice thick moss cover only means that it is too wet for the roots below. The roots are also very sensitive to pH and salt build-ups in the soil, as in areas with hard and alkaline city water. If there is a little swing in pH, it will drop a root or two or simply die quickly. This is why replacing the soil in 2-3 years is a must. I think the problem with this relatively new variant of elm is that it has not developed a good mycorrhizae fungus partner.

 

[Shibui]

I think the problem with this relatively new variant of elm is that it has not developed a good mycorrhizae fungus partner.

It may have only recently been introduced into Western cultivation but I have seen it listed as an 'older' cultivar.
I had assumed this is a natural variation adapted to the colder climate of Hokkaido Island but maybe that's not the case - it would be hard for any plant this brittle to survive in the wild, let alone in harsh conditions that usually give rise to natural dwarfed forms!

 

[ShadyBonsai]

Ah I picked up a Hokkaido earlier this summer as well, didn’t do much with it other then clean up the top shape a bit. I would love to develop the trunk out a bit more - do you guys think this could be reported into a larger pot without issue to increase trunk size?

 

[Shibui]

That one looks well established in the pot so should have plenty of roots and transplant without the root ball falling apart. I would certainly be happy to upsize to a larger pot. Just lightly rake the outer roots so some will grow into the new soil. Also keep a close eye on water in both old and new soil. Sometimes water is reluctant to cross the boundary between old and new and the section with roots can get dry despite the new soil having plenty of water. Lightly raking the roots helps overcome this to a degree.
Don't go too big at first. Hokkaido grows slow so it can take longer for the roots to occupy new soil. New soil without roots can cause problems so upsize in steps rather than straight into a barrel sized pot.

 

[parhamr]

@badatusernames how is the tree looking? Are you planning to give it more root space next year? Mine had done really well with a few years of careful rootwork, overpotting, and free draining 1:1:1 soil mix.