Allowing to extend and partially defoliate vs cutting back after 3-4 nodes

[Rodrigo]

Just like everything else in bonsai, I've seen different information on refining elms depending on where I look. I'm specifically talking about the difference between allowing my elm to grow, to then partially defoliate it 2-3 times a year versus allowing it to extend just 3-4 nodes and cutting back to 1-2. This is a Siberian Elm in refinement and in trying to increase terciary branching, I know it's not meant for trees in development.

As far as I understand, in order to defoliate successfully, the tree needs to grow and gain enough energy to be able to handle having to push out new leaves multiple times a year. But if I'm only allowing 3-4 leaves before cutting back, that's not giving the tree enough time to regain spent energy, is it?

Are they different methologies meant to be used separately? When should I use one or the other?

 

[WNC Bonsai]

Same question, different elm species. Some say let extend about 6-8 then cut back to 2 leaves. Others say let em grow out them cut back in one fell swoop once completely hardened off and stem has gone completely woody. Is one approach for development and the other refinement?

 

[Hartinez]

For me personally, I do both with my Siberian elms. Sort of. I’m a fan of letting the tree flush through spring and push long extensions of growth. Then I go through and defoliate trim and wire, then let it flush again. I will then do 3 sometimes 4 more cutbacks.

The defoliation turns single leaves into new branches and the trimming bifurcates. Gives me more to work with and cut back to when I’m doing my multi season trims.

 

[Rodrigo]

Same question, different elm species. Some say let extend about 6-8 then cut back to 2 leaves. Others say let em grow out them cut back in one fell swoop once completely hardened off and stem has gone completely woody. Is one approach for development and the other refinement?

Right? It does get kind of confusing.

For me personally, I do both with my Siberian elms. Sort of. I’m a fan of letting the tree flush through spring and push long extensions of growth. Then I go through and defoliate trim and wire, then let it flush again. I will then do 3 sometimes 4 more cutbacks.

The defoliation turns single leaves into new branches and the trimming bifurcates. Gives me more to work with and cut back to when I’m doing my multi season trims.

I would think that letting them grow out to regain energy is better for the tree in the long run. The "cut back after 3-4 leaves" method basically never allows the tree to harden off so it's always spending energy and right when it's about start gaining again they're cut off and the cycle restarts.

Then I go through and defoliate trim and wire, then let it flush again. I will then do 3 sometimes 4 more cutbacks.

Are you saying that you defoliate the first time and then cut it back 3 or 4 times at 3-4 leaves for the rest of the season?

 

[Hartinez]

Right? It does get kind of confusing.


I would think that letting them grow out to regain energy is better for the tree in the long run. The "cut back after 3-4 leaves" method basically never allows the tree to harden off so it's always spending energy and right when it's about start gaining again they're cut off and the cycle restarts.



Are you saying that you defoliate the first time and then cut it back 3 or 4 times at 3-4 leaves for the rest of the season?

Yes, I defoliate first. Then i cut back. Then i let everything extend again, then start my periodic cutbacks. Only with my Siberian elms. I never cut back or defoliate after 3 or 4 leaves have grown. If I did that, I would be trimming the tree 10 times in one summer. Even prolific growers like Siberian elm want to extend some. Id say the extensions are like 10-12 leaves or more. Then i cut back to 2 or 3 depending on directionality. I have just found that Siberian elm respond really well to this system.

 

[Shibui]

Allowing shoots to grow longer will also thicken those shoots and branches they are growing from. In some cases that may be desirable but where I need to limit thickening I choose to cut back earlier.
Thickening branches may sound insignificant but they can quickly get way too thick to look good on the trunk, especially toward the top of the tree. A number of times I have had to chop off entire branches because they were too thick.
I have often allowed lower shoots to grow long while trimming upper shoots more simply because upper shoots grow more, thicken more and are generally more vigorous. Leaving lower shoots to grow more leaves lets them thicken and gain strength while we weaken the upper areas a bit.

I would think that letting them grow out to regain energy is better for the tree in the long run. The "cut back after 3-4 leaves" method basically never allows the tree to harden off so it's always spending energy and right when it's about start gaining again they're cut off and the cycle restarts.

This is just conjecture. In practice most trees cope well with continual trimming. Every leaf is producing food as soon as it turns green so it matters not whether the shoot is hardened off.

 

[Hartinez]

Allowing shoots to grow longer will also thicken those shoots and branches they are growing from. In some cases that may be desirable but where I need to limit thickening I choose to cut back earlier.
Thickening branches may sound insignificant but they can quickly get way too thick to look good on the trunk, especially toward the top of the tree. A number of times I have had to chop off entire branches because they were too thick.
I have often allowed lower shoots to grow long while trimming upper shoots more simply because upper shoots grow more, thicken more and are generally more vigorous. Leaving lower shoots to grow more leaves lets them thicken and gain strength while we weaken the upper areas a bit.


This is just conjecture. In practice most trees cope well with continual trimming. Every leaf is producing food as soon as it turns green so it matters not whether the shoot is hardened off.

Shibui nailed it. He’s so much better at explaining these things.

 

[Hartinez]

Here’s an example. This branch is extending and has 7 leaves with new ones still emerging. I’m nowhere near ready to cutback or defoliate this branch. I want this branch at least twice as long. At least. Probably longer for the lowest branches to thicken up more (as @Shibui mentioned)

 

[WNC Bonsai]

Allowing shoots to grow longer will also thicken those shoots and branches they are growing from. In some cases that may be desirable but where I need to limit thickening I choose to cut back earlier.
Thickening branches may sound insignificant but they can quickly get way too thick to look good on the trunk, especially toward the top of the tree. A number of times I have had to chop off entire branches because they were too thick.
I have often allowed lower shoots to grow long while trimming upper shoots more simply because upper shoots grow more, thicken more and are generally more vigorous. Leaving lower shoots to grow more leaves lets them thicken and gain strength while we weaken the upper areas a bit.


This is just conjecture. In practice most trees cope well with continual trimming. Every leaf is producing food as soon as it turns green so it matters not whether the shoot is hardened off.

I like this explanation a lot, especially where it comes to branch thickness. With elms it is desirable to have very fine branches since they can develop a lot of refinement quickly and get very twiggy which you want to be fine. On the other hand longer branches with more leaves provides more photosynthetic area and therefore more energy accumulation. I also saw a video that suggested that unless you let the branches lignify they will not produce new buds at the leaf axils—something I am testing right now with my zelkovas. In the greater scheme of things this sound like a tradeoff netween energy accumulation and tree health. On weak trees or branches it may be more desirable to let em grow out more then cut back once they get all the extra energy. But on strong trees and branches it should be safe to go ahead and prune back at an earlier stage. Seems the same as with a lot of energy balancing practices.

 

[cmeg1]

I’m a fan of letting the tree rest a little…..good,dense triangular shaped grow-outs will keep them very energetic and making their energy builds and can trim more often to get density.

Also I like to get them equal and slightly triangular shaped and then just pinch tips so they actually stop growing and assimilating nitrogen…..this builds brix and makes roots stronger and smaller,stronger cells in the plant…….so I employ a little of both.

From experiance I have seen full defoliation and trim at the same time produce incredibly short internode…..say to let extend..then trim to 2 and proceed to defoliate at that same day.
New growth will have very short nodes good for refinement……

I have not defoliated this Siberian Elm……its not yet 2 years old even!!!!

I trimmed yesterday,but not the whole thing as about 50% of shoots were not thickened as the rest yet….this one is getting nice and gnarly twigs already.

I love how they look as air/ground-layers……I plan to make about 200 or so trunks for next Autumn…….grow them straight through starting mid summer in co2 through winter and all season outdoors in 2024…..ground layers like this…..perhaps better as I layered this one as a sapling….the next batch will be layered when trunks are nearly an inch.

I like Siberian Elm…..the bark and roots gets really nice lenticles forming quite early.