I have a dawn redwood that’s been growing freely in a five gallon bucket for quiet awhile now and want to trunk chop this year - is now a good time or should I wait until the buds are pushing, like repotting? Currently in SF, so zone 10b.
I like making big cuts when the tree is active so it can start healing as soon as possible. Another option is to make the cut above the final cut location so the sap can withdraw over time and then make the final cut 6-12 months later.
Thanks Jonas! Yeah, the plan is to make a horizontal cut now a little above, then pick a new leader from the resulting shoots and make an angled cut above that later.
I also managed to dig up the article I was originally using to guide me:
"You should probably never perform this operation as the leaves are coming out, wait until the new leaves have hardened off, usually in a month or two. Before the leaves emerge, the roots are at maximum storage capacity. If you prune then, all that food is going to look for buds to expand, and the growth will be explosive, coarse, and with long internodes. This is exactly what you want if you are only looking to develop the next section of trunk, the portion between branch 1 and branch 2. This will give you the most rapid development. Identify the new leader quickly and protect it. If you are lucky it will be right at the top of the cut that you made.
If you perform this operation after the leaves have hardened (or sooner), you do it when the roots are depleted. They spent a great deal of food (energy) to produce all those new leaves and shoots. This is not conducive to developing a new leader unless you want a weak one with close internodes, such as if you want to develop a new apex at the top of tree. It is also preferable for trying to get buds to break for new branches on fast growing trees, because the new growth will be more refined with closer internodes. " - Brent Walston
Thanks! That idea makes sense. When it comes to your tree, the best timing may depend on the stage of development. If it’s in the early stages of development and coarse growth won’t cause any problems, now could work well. If you want the effect to be less pronounced, waiting until spring can help.
I usually cut when I get the chance. If I’m concerned about the tree having too explosive a response, I cut higher, let the tree produce more buds, then select a shoot to work with once the tree slows down.
You’d think I’d learn by now, the answer with bonsai is always “it depends on what you’re trying to achieve”