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castorcrap:

This is a common confusion about training young material as bonsai. Chopping the trunk and training a new leader will definitely stop the thickening of the trunk, so it's best to do this when you have almost achieved the trunk girth you desire. I would generally avoid chopping the leader more than once a year, and in extreme cases, you need to wait longer.

Check out my article here to see what I did this year on this large caliper trident maple. I will be posting an update soon, but the new leader is only about 3/8 of an inch from this year's growth, and directly below it is almost 2 inches. I need to let the new leader grow unhindered until it is about 2/3 the size of what's below it and then chop it. All this is done with the final height already in mind. I will chop this at least twice more, each time a little further up on the new leader, but the chop distance will diminish as I get to the apex or crown of the tree.

Trying to develop the branches and the trunk at the same time is tempting, but you will not achieve what you want on either score. Grow the trunk to what you want, then work on the branches. Properly ramifying a tree is a process of weakening the tree, holding back its growth to achieve balance throughout, so you cannot gain much in the way of trunk size through this process. And if you let the tree grow unrestrained to increase girth, the branches of course get outsized, too.

Keep in touch with my article- this spring I will be pruning the branches to the first bend, but I will leave the new leader to grow unhindered. I may get the new size I want in one year, but it may take more. The tree needs repotting this spring, it's a big job and I will document it carefully on the website.

Now--you don't mention what species you are working with. I have mentioned general guidelines for trunk chopping, but each species and each individual tree is different. What are you working with, and what are your goals? Can you post some photos?

Good luck to you!
Chris

Hello, I recognized your picture instantly, Ive had that site on my favorites list, because its one of the few sources Ive found about how the heck to get started with a collected tree/stump from the wild. Of all my 13 books, there is hardly any good info on this important first step, all my books spend most of the text talking as if you already have a bonsai and how to maintain it. Mostly I have multiple oaks, ironwood, beach, many maple species, hawthorne, hack berry, plum, quince, ginko, hawthorne, even sycamore despite the big leaves. Also a dawnredwood,cypress, junipers, atlas and deodora. I am in medical school and have all my trees Ive collected with me here at school in pots, some are 9feet tall. My only option to get them home (300 miles away) and planted in my garden is our thanksgiving break or Christmas break, after that its boards and rotations. I wont see my trees but once a year possibly. But I dont care, I just want to get them fat so that when Im done w/ residency I will have some good stuff to work with (I will of course annually dig and plant right back to prevent tap roots). My big questions are: Even though it will slow down thickening is it okay to chop them so I can get them in my truck and so they wont take over the whole garden (Im in no hurry since it will be 6 years before Ill get to train them anyways)Also Can I do this heavy pruning/chopping in late Nov. or late Dec. if its my only choice? Can I do the root chopping (tap root preventing in these cold months as well?) Im so sorry for all the questions, but ive tried so many books and postings and just cant seem to figure out what to do to get these trees off to a good start so that I can do bonsai after medical school.
Thankyou so much to who ever reads all this :) castorcrap

You can probably do a partial chop now, meaning you are cutting away enough of the trunk to move it but you are not cutting anywhere near where the final chop will occur. You are doing this because you have to, and you should only cut away enough of the top to move the tree. This isn't the right time of year for chops, and you're likely to get dieback along the trunk when you do it now. I wouldn't mess with the roots at all this time of year. If you do, you may lose some trees over the winter. For zone 6, you are planting these trees out quite late in the season and they won't really establish themselves before the cold weather arrives. Mulch them and water them well until the ground freezes. Spring time when the buds start to swell is much better for root work.

Dave

Hello again. Right now I have 2 trees per 10" pot, their root systems are small enough where I could separate them and quickly,& carefully put them in the ground, and mulch them. Is this still to traumatic to do in november zone 6?
thankyou

Maybe the best solution would be to plant them out without touching the roots at all with the plan to dig them up in spring to do your rootwork. Some people will actually plant the trees out in their pots with the idea of digging them up in the spring. However, if the root systems of the potted trees aren't horribly entangled and you can seperate with minimal damage, that's ok, too. I just wouldn't perform significant root pruning/rearranging in November, even for very hardy stock.

Dave

Thankyou Dav4, you have answered my ultimate question, I owe you forever! And thank you for the info on trunk chops. I do still think about the fact that: you are supposed to reduce leaf volume if you have accidentally or purposly removed some root material (example = digging up a tree). So when ever you harvest a deciduous tree is it advised to some remove leafs/buds to reduce transpiration, but never ALL of them? I guess what im asking is, "trunk chopping down past any visable buds, can completely kill a tree if it is not 100% healthy, or is there there usually enough old leaf node areas hidden in that bare trunk to force out some buds even w/ a reduced root system?" Sorry for all these questions, I just cant find them out anywhere, but after this I should be set to go. Thanks again, castor crap :)

That depends on the species in question. Most evergreens/conifers will be killed outright if you chop below the last bit of foliage. This may not be true for Dawn redwoods and baldcypress, for which I don't have much experience. Japanese and Trident maples will have dormant buds up and down the trunk that will awaken after a severe trunk chop, assuming the tree is healthy. Don't chop more then you need to right now. Also, there is controversy concerning the recommendation to remove a similar percentage of crown when reducing the rootball. Don't forget, the crown serves as the energy maker for the root system, and the tree as a whole. Reduction in the crown will serve only to reduce overall energy production and vitality of the tree. I think this is less of an issue for deciduous trees that have dropped their leaves for the year and are no longer photosynthesizing. Again, your goal now is to get your trees through the upcoming winter. Less is more right now.

Dave