Sweetgum bonsai three years in training, showing fall colors.
Another of the very best bonsai trees for beginners, the Sweetgum (Liquidambar styraciflua) is a member of the family Altingiaceae.
It’s a primary tree, growing to heights of 60-100’. Leaves are 3-6” in length and width on a petiole roughly the same length, and star-shaped.
Bark is gray and deeply furrowed, developing about 10 years after seedling stage.
Best Features
Growth habit: Sweetgum grows very vigorously, producing shoots in a container that can grow up to two feet in length in a single season. Collected specimens backbud very well, which allows the artist to select the branches necessary for producing a tree-like structure on a small scale. Sweetgum also grows continuously throughout the season. It isn’t bothered significantly by any pests or diseases, aside from munching caterpillars in spring.
Leaf-size reduction: the leaves reduce to about half their normal length with proper pruning and pinching techniques. The petioles shorten as well.
Ramification: simple to produce as the species buds well in the internodes and will continue to do so throughout the life of the tree. I recommend constant pinching during the growing season, and I do not recommend terminal bud removal in late winter (this is an update from earlier information); removing terminal buds in late winter can result in death of the entire branch.
The specimen to your left is showing good development and ramification after only three years of training from a mostly bare trunk.
Root growth: once containerized, Sweetgum produces roots with extreme vigor. Root-pruning should be done every other year without fail, in May or June.
Worst Feature
Sweetgum can be affected by hot summer temperatures on the bonsai container.
Roots tend to always seek the edges of containers, and in the high heat of summer pots can get well over 100°F. This scorches the tender roots at the edge of the container, and this is reflected as brown or black edges to the leaves, which are thinner than those of other species.
Providing shade in summer for the tree or just covering the pot can mitigate this problem.
Sources of Sweetgum
Both native Sweetgum and Oriental Sweetgum, Liquidambar Orientalis, are available commercially along with cultivars of both. Bonsai nurseries also offer them.
Seedlings are usually plentiful in areas with mature trees, and these may be collected in May or June along with larger specimens. Always defoliate when collecting Sweetgums regardless of size.
If you collect your own: Sweetgums should be collected in May or June. I always recommend use of a cordless reciprocating saw to make the work easier.
- Cut the trunk to roughly 12-24”, then sever the lateral roots to within 4-6” of the trunk.
- Thrust the blade up under the tree and sever the taproot.
- Most trees should be out of the ground in under five minutes using this tool.
Once it’s time to pot the tree initially, first wash off all the native soil. Then re-cut the roots closer to the trunk in anticipation of the eventual bonsai container.
New roots will sprout mostly from the cut ends of the larger roots, so dust near the ends with rooting powder.
Pot in prepared soil.
Be sure to bury the surface roots to ensure they don’t dry out as the tree recovers.
As a final step, seal every cut on the trunk that’s ¼” or greater in diameter with cut paste.
Other Information
Watering: normal watering routine. Always use a well-draining soil.
Feeding: either organic or inorganic at full strength during the growing season. No special requirements.
So What Do You Think?
Sweetgum is a great tree for beginners or even seasoned bonsai artists. But I would really enjoy hearing your thoughts and your suggestions! I’m always happy to answer any questions you have. Just leave your comment(s) below and I’ll respond to you right away.
Thanks!
Zach
Just found this post and it’s very helpful, I hope you are still active on it. I have several small sweetgum’s that sprouted from seeds in my yard. At the time, I pulled them up and stuck them in 5 gallon buckets for fun. They are now approaching 2-3 yrs old and I am interested in developing one or two into bonsai. Should I pursue a trunk chop before repotting into a training pot? The trunks are not yet thick enough to suit a bonsai, but they are growing quite tall (3 feet tall).
The trunk needs to be at least 3/4 the desired size before going into a training pot. Trunk size does not increase very rapidly in a pot, so that part needs to be completed before real training begins.
What height & spread can the sweet gum bonsai achieve (ball park figure – just to give me an idea). At present I also have a different and anonymous bonsai seedling, approx 9 months old. I’ve been told not to report or do anything until at least a year, but the seedling is right at the edge of its pot, so I’m not sure how that might affect the progress.
You can grow any bonsai to the maximum acceptable size, which is taken to be about four feet tall. As for spread, that would depend on the design of the tree but it shouldn’t be more than two to three feet in my estimation. As for your seedling, it will only slowly get to a reasonable trunk thickness to make a believable tree while growing in a pot. Pot growth slows trunk thickening. Be careful not to make a thin-trunk specimen that’s too tall or broad; the proportions will not look right.
I hiave a root over rock sweet gum that’s been in training for just under a year. The leaves started to develop brown spots and edges, but after reading about how the black container could heat up too much, I think that could be it. I’ve moved it into a shady area, so I’m hoping it’ll bounce back. Just did my first repot, exposing a little more of the roots.
What type of soil do you recommend when you initially pot the ones that have been collected?
I use a coarse bonsai mix, meaning unscreened 50:50 expanded shale and pine bark (from the pine bark mulch you can get at Home Depot). I also now leave some native soil on the tree, and I am experimenting with foregoing chemical fertilizer on the species with good results as of 5/2021.
I have a pair of volunteer sweetgums that planted themselves in a nursery pot about 2 to 3 years ago. Is it really the right time now to remove them? The roots have extend far beyond the confines of that pot. They are fully leafed out and I thought that it was better to collect trees that have not quite leafed out yet.
I tried to attach a picture but it didn’t work.
You can take them out of the pots, root-prune and defoliate, and they should come back fine in a couple of weeks.
Zach, question about terminal bud removal. I collected multiple heavy trunks two years ago that have done wonderfully. I’m concerned with removing the terminal bids however, as I have heard that removal prior to leaf extension can cause the auxin to withdraw and can lead to total branch death. Thoughts/your experience with this? Thank you!
Thank you for the comment, Cullan. I actually need to edit this post, because I have come to learn the hard way that removal of terminal buds can lead to branch death. I do not recommend it any longer.
Thank you so much for the information. There are many sweet gum seedlings in my yard that I can now use for bonsai.
You’re welcome, Mike. Glad to help.
Hi Zach, thank you so much for being here.
I am new to Bonsai, and have started a Sweet gum from Seed, I am quite surprised at how quickly he has grown (2ft and our summer isn’t over yet) and wondered if this is normal? the leaves appear very large also.
Thank you in advance for any help and tips
That’s totally normal, Scott. Sweetgums grow very fast when young. The leaves are normally large, but will reduce in pot culture.
I recently dug up and potted a fairly large sweet gum that was broken and growing at an angle. It had a number of larger roots and a few smaller roots. Do you think it will survive over the winter?
I don’t lift Sweetgum at this time of year, so can’t speak from experience. It’s not something I would do, unless the tree would be doomed otherwise. Sorry I can’t be of more help.
When you write ‘collect in May or June, ‘ you mean, collect In mid winter when the tree is dormant? I’m in the UK, so I guess or seasons are 6 months apart?
It would be helpful if you could put the seasons in brackets street the month.
No, our May and June are after first flush in spring. I have collected Sweetgum during winter and after first flush, and my success rate is much better in spring. The tree must be defoliated. You should try collecting during dormancy and after first flush, as your climate is much different than mine.
Hi Zach, thank you for publishing so much great information. I’ve got sweet gum trees all over my property and plan to dig some this spring per your instructions. I’ve noticed much variety in them, red, yellow even purple fall foliage. I’ve also noted several with a corky looking bark as well as winged bark. Is there any reason to avoid any of these traits? I assume they will just add interest to my collection.
No reason to avoid any of the traits you mentioned. Wait till around May to collect Sweetgum. The success rate is much higher.
I am very new to bonsai and I find your site extremely helpful. Thank you.
I appreciate the kind words, Jim.
Thank you for this article on maple trees. Can you please help me with a problem . My maple trees are turning their leaves bottom to the sun and then stop new shoots. Thank you izak
It’s hard to diagnose a problem without knowing more. Where do you live, what type of maple is it, and how long has it been in its container? If you could email me a couple of photos that would also help.
Hello , nice post, can I grow liquidambar indoor? Thanks
No, Jose, liquidambar are strictly outdoor species.
I am new to bonsai and am very glad I found your site. Great info. Thanks!
If I might ask a question. We have a gum tree we planted three seasons ago but the main trunk died. Multiple trunks sprouted and grew well. Thinking of making this a clump bonsai. Should I cut back and start basic training while still in the ground for a season or two, or dig up and start training in a pot?
Best wishes.
It depends on whether the new trunks are the thickness you desire. When you lift the tree, their thickening will slow down dramatically. So wait until you have the trunk thickness you want, then lift. Be sure to wait until May or June.
I was wondering what the best time to carve the chop on a Sweet Gum is? I’ve spotted three Sweet Gums I’m going to collect today. If I’ve already decided my leader for the apex, should I wait till year two to start shaping the enitial chop? Or can I carve it when I defoliate and pot the tree for the first time?
I wouldn’t carve when first potting, but an angled cut should work fine. You can carve in year two. Be sure to seal all chops.
Thanks for the help Zach. I was also wondering when would be the best time to collect American Beech and Magnolia? There’s a lot of these trees growing by a streem on my property and I thought I might as well put some in a pot. Any advice would be appreciated.
Beech is best collected in winter, Josiah. I’ve never collected magnolia (which is not really a suitable bonsai subject), so can’t advise on the species.
Your website is just beautiful. And so much help to me. My son has expressed such an interest in bonsai for the longest time. I had no idea that I could go out and dig up a sapling to get him started. We live in an area where sweetgums grow everywhere and grow vigorously ! I have a plan now. Thank you so much for your efforts in bring this information to the public and especially to me.
Hi Zach,
I came across your “Bonsai South” website today -(Thursday 11th June 2015, Sydney, Australian time)
I recently got myself an American Sweet Gum bonsai tree on Tuesday -9th June 2015, and I was searching for information regarding this tree and how to care for it, and found your site on this Liquidamber Styraciflua species very interesting. I don’t think are are many such Liquidamber trees avaliable in Australia, -so I was very surprised to see any -let alone a bonsai version in my local garden centre.
Since I live in Sydney, Australia, – obviously our seasons are in reverse to yours, -so this American Sweet Gum bonsai I’ve got is in it’s dormant stage.
I’m looking forward to spring when it will begin to emerge from it’s winter slumber and see it’s buds begin to grow and unfold into leaves.
Hope to hear from you soon.
Regards
Darren
Sydney, Australia
It’s great to hear from you, Darren. I think you’ll find sweetgum a wonderful species to work with. They’re a little unusual in their growth habit, which you’ll find out as you begin to work with the species. But they are vigorous growers, which makes training go faster than for many others.