Advice on how to shape tree?

[Wally5]

Hi! I posted a while back about my citrus, which was struggling at the time. I got a grow light, as advised, and now I have the opposite problem. It's gotten too tall for the framework I have the grow light on, and it isn't branching out. Any tips? Tree is about 4 years old now; I sprouted it from seed in 2020. Central VA. Tree is indoors right now due to temperatures.
Cutting the sprouting area has worked in the past, but not well. There has only been major growth on one of the halves of the split.

 

[Shibui]

Pruning is the key to making almost any plant branch out - ramify. Most plants are pre-programmed to grow tall. In nature, the fastest to the top wins so it's no wonder your tree just wants to grow up.
The healthier the plant is the more new shoots you'll usually get after pruning. That may explain why your last attempt only produced 1 new shoot - it just did not have the spare energy to do any more.
I also find that cutting further back also tends to make more new shoots. Simply snipping the growing tip often only stops the growth for a short time and one new shoot takes over. Cutting back into thicker, older wood will often give better results. Plus it will give you a bit longer before the tree reaches grow light capacity again.
Some species are frustrating because they don't seem to like to grow lots of shoots. Ginkgo is one but I've also found that many citrus are slow to develop lots of branches. Don't give up though. Keep pruning whenever it needs doing. Eventually the branching will begin to build up.

 

[Wally5]

Pruning is the key to making almost any plant branch out - ramify. Most plants are pre-programmed to grow tall. In nature, the fastest to the top wins so it's no wonder your tree just wants to grow up.
The healthier the plant is the more new shoots you'll usually get after pruning. That may explain why your last attempt only produced 1 new shoot - it just did not have the spare energy to do any more.
I also find that cutting further back also tends to make more new shoots. Simply snipping the growing tip often only stops the growth for a short time and one new shoot takes over. Cutting back into thicker, older wood will often give better results. Plus it will give you a bit longer before the tree reaches grow light capacity again.
Some species are frustrating because they don't seem to like to grow lots of shoots. Ginkgo is one but I've also found that many citrus are slow to develop lots of branches. Don't give up though. Keep pruning whenever it needs doing. Eventually the branching will begin to build up.

Thanks, I'll try that. Should I cut off all new growth or trim the less developed branch back a bit?

 

[Shibui]

Most trees are apical dominant. See above about wanting to get tall quick. That means if you prune one part but leave another section taller the taller section will get all the resources while the chopped part won't grow much, if at all.
Much better to prune all upper parts at the same time so 1 does not take over.
I'd probably cut at the red lines in this pic

but you could even go lower and cut below the existing fork.

 

[Wally5]

Most trees are apical dominant. See above about wanting to get tall quick. That means if you prune one part but leave another section taller the taller section will get all the resources while the chopped part won't grow much, if at all.
Much better to prune all upper parts at the same time so 1 does not take over.
I'd probably cut at the red lines in this pic
View attachment 577683
but you could even go lower and cut below the existing fork.

Alright, thanks! Would it be best to wait until growing season when I can have it outside, or just do it now?

 

[Shibui]

I believe you said it is currently growing and now too big for the light frame. Does that not mean growing season?
I think citrus can probably be allocated to the 'tropical' group which means you can prune whenever the tree is growing, whether that's indoors or out.
In my experience, trees can be pruned pretty much any time of year. Sometimes you might wait a few months for a response but it will shoot and grow whenever the time is right.

 

[Attmos]

Most trees are apical dominant. See above about wanting to get tall quick. That means if you prune one part but leave another section taller the taller section will get all the resources while the chopped part won't grow much, if at all.
Much better to prune all upper parts at the same time so 1 does not take over.
I'd probably cut at the red lines in this pic
View attachment 577683
but you could even go lower and cut below the existing fork.

Looks like the light comes out of one side of the grow light, do you turn the tree so that all sides get some time under direct light?

As far as the plant getting too tall for your lighting structure... personally, I would just raise your light a little higher and place a few mirrors around the tree. Light reflected by a mirror is magnified, so even though the light is further away from the lower part of the tree, the mirrors will provide ample light for lower leaves and branches.
That or you could get another light to use for the lower half of the tree.

This is, of course, if you choose not to cut your tree now. I'm very familiar with indoor horticulture and lighting needs, but very very new to bonsai. So...

Good Luck.