Trimming the tree...Elm that is.

[Tieball]

I have and American Elm bonsai tree in development. It is a good-sized tree but "in development" yet. The tree sits in my unheated garage over my West Michigan winter. It is cold and stays cold until at least the end of March. This past growing season I let numerous branches on the Elm just grow wildly to encourage branch thickness. In the coming year I want to begin more secondary branch development..the start of ramification. Now...the question: When I get into spring next year is is best to prune back before the buds begin to swell? Or...is it better to prune after the buds begin to swell? I would be cutting back to a dormant bud where one can be found. The branches are all healthy right now. My thought is that if I wait for bud swell then I am cutting off a lot of good deal of energy sap sent out to a branch...just to throw it away. What have others experienced?

If cut back hard before the bud swelling does the tree "find" buds on a branch and activate them?

 

[jk_lewis]

Frankly, I'd cut it back now.

 

[0soyoung]

IMHO, it doesn't matter much, but pruning after leaves have emerged is safer. On the other hand, it is easier to see the structure when foliage is not in the way.

First, the braches of a tree a pretty much autonomous and the starch to get each bud open is stored within it. In other words, the start up energy available to what you leave on the tree is the same as before you cut it. The buds and the cambium are activated by temperature - warming after a suitable period of cool dormancy. Locally stored starches are converted back into sugars and fuel the new growth. Water and nutrients are not drawn from the roots until the newly emergent leaves have begun transpiring.

So, if one prunes during dormancy, one must be careful not to remove all the buds. This almost certainly will produce a dead branch. On the other hand, if the tree is actively growing, there will be cytokinins in the branch so the collapse of the auxin flow, caused by pruning off all the branch's active foliage, can release latent/adventitious buds (this is just defoliation taken to an extreme).

Regardless of which way you choose, new growth will likely tend to bolt. You can arrest this and cause more back budding by pinching out the shoot apices.

 

[Zach Smith]

I have and American Elm bonsai tree in development. It is a good-sized tree but "in development" yet. The tree sits in my unheated garage over my West Michigan winter. It is cold and stays cold until at least the end of March. This past growing season I let numerous branches on the Elm just grow wildly to encourage branch thickness. In the coming year I want to begin more secondary branch development..the start of ramification. Now...the question: When I get into spring next year is is best to prune back before the buds begin to swell? Or...is it better to prune after the buds begin to swell? I would be cutting back to a dormant bud where one can be found. The branches are all healthy right now. My thought is that if I wait for bud swell then I am cutting off a lot of good deal of energy sap sent out to a branch...just to throw it away. What have others experienced?

If cut back hard before the bud swelling does the tree "find" buds on a branch and activate them?

American elm is a strong grower, so it probably doesn't matter when you prune. For cuts 1/2 inch and over I'd recommend sealing, to prevent drying out and potential dieback.

Cutting back hard on a larger branch does cause the tree to "find" a bud; but such buds are actually located at points where leaves emerged on the original shoot that grew into the branch. Most species behave this way.

Zach

 

[jk_lewis]

If your intent is to remove the end buds (and perhaps a few others) to promote ramification, you pretty much need to do it when the tree is bare so it can redirect the springtime energy into buds farther back on the branch.

I do this every winter on hornbeam, maple, crape myrtle, pear, Osage orange, etc. In short, almost all of my true deciduous trees.

 

[Tieball]

IMHO, it doesn't matter much, but pruning after leaves have emerged is safer. On the other hand, it is easier to see the structure when foliage is not in the way.

First, the braches of a tree a pretty much autonomous and the starch to get each bud open is stored within it. In other words, the start up energy available to what you leave on the tree is the same as before you cut it. The buds and the cambium are activated by temperature - warming after a suitable period of cool dormancy. Locally stored starches are converted back into sugars and fuel the new growth. Water and nutrients are not drawn from the roots until the newly emergent leaves have begun transpiring.

So, if one prunes during dormancy, one must be careful not to remove all the buds. This almost certainly will produce a dead branch. On the other hand, if the tree is actively growing, there will be cytokinins in the branch so the collapse of the auxin flow, caused by pruning off all the branch's active foliage, can release latent/adventitious buds (this is just defoliation taken to an extreme).

Regardless of which way you choose, new growth will likely tend to bolt. You can arrest this and cause more back budding by pinching out the shoot apices.

Thanks...clear explanation....and in an understandable way that can be taken to the tree. I did not quite get it, although I've read a lot and listened a lot on tree growth, that the buds have all their gear packed and are ready. Come warmer weather just need an energy shot to get moving and start a new growth year. I may have oversimplified a little.

 

[Tieball]

If your intent is to remove the end buds (and perhaps a few others) to promote ramification, you pretty much need to do it when the tree is bare so it can redirect the springtime energy into buds farther back on the branch.

I do this every winter on hornbeam, maple, crape myrtle, pear, Osage orange, etc. In short, almost all of my true deciduous trees.

Thanks...makes sense...especially this part "so it can redirect the springtime energy into buds farther back on the branch".

 

[Tieball]

American elm is a strong grower, so it probably doesn't matter when you prune. For cuts 1/2 inch and over I'd recommend sealing, to prevent drying out and potential dieback.

Cutting back hard on a larger branch does cause the tree to "find" a bud; but such buds are actually located at points where leaves emerged on the original shoot that grew into the branch. Most species behave this way.

Zach

Thanks...I'm probably a little timid on my cutting back yet but am learning. This spring coming up will be a good observation time when I can take the comments received, act and see how they play out on the tree.