Someone asked me for tree-trimming tips and I might have actually answered before but let’s do it again.

1. Always cut back to a side branch, which will then become the main branch. You can’t arbitrarily cut a branch to length like hair, if you try that it won’t grow back from there instead a bunch of “waterspout” shoots near the end will head straight up next year and get real long and spindly
2. Wood is “built” using photosynthesis-powered carbon capture at the leaves and water and resources pumped up from the roots. This means a given “patch” of sunlight can grow about the same amount of wood whether it’s split among one branch (and its sub-branches) or many
3. Branches grow (differentialy) towards light but will avoid contact with each others’ leaves. This means if you have too many branches “competing” for the same arc of canopy and sunlight they can get long and skinny and all trying to shade each other out
4. The natural inclination of a branch is to further branch, chemicals generated at the very apical tips of branches and flowing mostly downhill from there suppresses it (this is why horizontal branches branch more than vertical trunks where it’s all very downhill)
5. On the other hand the resources generated in leaves and roots is also hydraulically spread and so the material to make new wood is preferentially found at the lowest point, once growth is sloped down sufficiently it will rapidly grow down to the earth (or at least shade)
6. As a tree grows, shorter, lower branches will get canopied in, and will tend to eventually sunlight-starve, rot, and get detached but manually trimming it can save the “maintenance cost” (and whatever shade it was casting lower down) of the wood in the interim
7. Know the energy cycle of your tree. Leaves generate energy, basically, to be used locally or further downhill. Depending on the tree in a season it will either flower first on last year’s growth and then grow new wood or grow new wood and then flower on it. By the end of fall, energy is sucked down into the roots for storage, this is a good time to trim branches cause you won’t waste any. At the start of the season it’s hydraulically pumped back up to the branches for growth. This is key for lower branches that are sorta shaded in – easy to pump to but don’t generate as much locally off leaves. Also when the canopy is cut back to less than the root system’s support capacity it really encourages upward growth as plenty of energy is pumped high.