I’ve got a wattle that currently has a thinner than ideal trunk. I’ve been looking into what I can do to encourage it to develop a thicker trunk. Mostly this seems to be about only providing the minimum amount of support it needs and keeping it loose so that the wind / swaying stimulates trunk growth.
But in passing I’ve heard that trimming the lower branches can also help. So far this is just a rumour to me and I’d like to substantiate it somehow. Have others heard the same?
Also - with the heat we’re getting lately do I need to worry about stressing out the tree? I probably don’t need to remove that many branches (should be less than 10%). Is there a good guide for how much I can trim without stressing the tree?
I’m not from Austrailia, but the general rule for pruning is that up to 30% of the crown is ok, so I wouldn’t worry at all about 10%.
This might already be your plan, but the best branches to prune are the ones with the most leverage. Those are the tallest and longest ones. The least effective will be the shortest, lowest, and closest to the trunk.
Unnecessary info: Trees need leaves to make food, but leaves use water and other soil nutrients. Trees need roots to gather water and other soil nutrients, but roots don’t make food. The balance in pruning is between these two things. Cutting off branches in the hot and dry will probably actually help the plant survive because you are reducing water demand during a time when food is plentiful. The trick is to not overdo it and starve the roots. That’s where that 30% idea comes from. Almost every plant will tolerate that amout of cutback without taking root damage.