Trimming is one of the few things you can do to a tree that helps it or hurts it depending almost entirely on when you do it. The cut is the same either way. What changes is what the tree is doing at that moment and what is in the air around it.
The general rule in Georgia is that late winter — roughly the dormant stretch before spring growth starts moving — is the best window for most trimming. The tree is not spending energy on leaves, the structure is visible without a canopy in the way, and the wounds close quickly once growth resumes. It is also the easiest time to see what actually needs to come off, which matters more than people expect.
Late summer through early autumn is the window to be more careful with. A tree heading into its slow season has less time to respond to a heavy cut before growth stops, and this is also when a lot of what causes trouble in wounds is most active. Light shaping is one thing; taking a lot off is another.
Species change the answer. Oaks in particular are worth timing deliberately rather than cutting whenever it is convenient, and flowering trees have their own logic — trim a spring bloomer at the wrong point in the year and you have removed next season's flowers along with the branch. This is exactly the kind of thing worth a short conversation before the saw comes out, because it is not recoverable afterwards.
Then there are the reasons that override the calendar entirely. A branch resting on the roof, growth pushing into siding or gutters, a limb hanging over a driveway where cars park, something dead and obviously loose — none of those get better by waiting for a nicer month. If growth is doing damage or sitting where it should not be, timing is a secondary consideration.
It is also worth saying what trimming is not. It is not a haircut you apply uniformly to everything in the yard once a year, and taking a lot of canopy off a healthy mature tree because it looks big is a good way to get a weaker tree and more growth to deal with next season, not less. The right amount to take is a judgement about that particular tree.
If you have trees that have not been touched in a few years and you are not sure what they need, call Alexander's Stump Grinding & Tree Service at (470) 939-8929. We will walk the trees with you, talk through what should come off and what should not, and give you a free estimate for the work.