Last year, I pruned and partially defoliated the Korean hornbeam below in early June. The timing was just about right for the work as each shoot had a moderate amount of new growth (see “Spring maintenance” for details).
This year the tree grew more vigorously – likely a result of being repotted – and was overly full by mid-May.
Korean hornbeam in spring
I knew the tree was ready for cutback and defoliation in early May, but didn’t get to the work until this week.
As I worked on the tree, I found that a number of the interior shoots were already starting to die off. Since one of my goals for this stage of development is to improve the fine branch ramification, I need to keep after the new growth on the exterior of the tree to make sure the interior branches receive enough light to maintain vigor.
After cutback and partial defoliation -18″ tall
If I’d waited until mid-June to prune, I would have lost valuable foliage in the tree’s interior.
I don’t worry about the timing as much for bonsai in earlier stages of development as they typically lack density. For these trees, I try to prune when the spring growth hardens off.
Going forward, I’ll trim or pinch new growth that extends beyond the current outline to give the interior shoots more of opportunity to gain vigor and fill in a few gaps in the tree’s silhouette.
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Gary McCarthy says
NICE tree!!!
For defoliation it looks like you’re doing full leaf removal as opposed to leaf cutting. Is that correct? Are you removing all the largest leaves or a certain percentage of leaves?
Thanks.
Jonas Dupuich says
Thanks Gary! That’s right – the leaves on Korean hornbeam are small enough that it’s much easier to remove full leaves than to cut them in half. I try to keep as many interior leaves as possible while removing enough to ensure the lower branches receive lots of light.
Gary McCarthy says
Got it. Thanks!
Thomas G says
Hi Jonas, I’ve been reading you blog for some time now- thanks for doing what you do here!
I have a question a bit off topic here, but I can’t seem to find the right info on spring cutback for crabapples. Most sources recommend pruning in later spring, ie after flowering; but some things I’ve read suggest that crabs are almost “single-flush” trees. I’ve got a tree in early development, 2nd year after collection, which has exploded with growth this spring and I was hoping to do some fairly major cutback to start establishing the shape.
Jonas Dupuich says
Thanks, Thomas! It would be interesting to know more about the concerns of what happens if they’re pruned at the wrong time. I treat crabapples like most deciduous trees and prune when the spring growth slows down (usually somewhere between April through June where I live). I pruned some a few weeks ago and they’re already covered with new growth. I’m letting another batch continue to grow as I want the branches to thicken more before I prune.
It may be that different species or cultivars respond differently to spring pruning. If you find that a tree or cultivar doesn’t respond well to the work, that will provide info for making a better plan next year.
Feel free to post a photo to the forum ask.bonsaitonight.com if you have specific questions about your trees.
Taboeric says
Do you know when to cut for white pine? Thanks
Jonas Dupuich says
Hi Taboeric! A common approach to white pine is to cut old needles when they start to turn brown, often in August. At that time it’s OK to start pruning or wiring white pines, though most white pine work happens in fall or winter.