After reading the posts about thinning and trimming trees and knowing what I know now that I didn't know about live oaks, (that they need to have the space of a golf course), I hate to even say but the lower limbs of my trees are tearing my back up when I mow. I have tried to cut the down-going limbs when they were small but the lower limbs are only 4-5 feet off the ground and getting bigger. I hoped as the tree grew upward, the lower limbs would somehow go up too. These are 2 trees in my yard that I planted 7 years ago, and they were supposed to be 3 years old then. I don't want to do any harm to them but don't want to wait until the limbs are giant and then decide I should have cut them...

Well, keeping in mind Howard's position that most all pruning is for the gardener/owner and not for the tree- sometimes you simply have to prune a bit to make life livable around your yard.

Just do what you have to and no more than that, and keep it in the good ol Natural Way program and things ought to work out decently.

_________________
Shepherd of the Trees
It is not our part to master all the tides of the world, but to do what is in us for the succor of those years wherein we are set, uprooting the evil in the fields we know so that those who live after may have clean earth to till.

Gotta love the live oaks!!!! Sometimes you can take some extra "weight" off of the ends of lower limbs and that will actually raise them up a bit. Unfortunately, you may have to remove the offenders if they are that close to the ground.

Be careful when pruning. If the main trunk forks there may be a tendancy to split when the tree matures. If pruning is necessary even trimming small young branches may cause it to fork.
We have a friend that was really picky about pruning her live oak from the time she planted it until it was a mature large tree until one day it split in half because it had 2 large forked branches.