Pruning can be extremely helpful if done right and extremely harmful if done wrong. It is vital to understand the proper way to prune - from timing to tools to trimming.
A tree may need pruning for a variety of reasons:
To remove diseased or storm-damaged branches
To thin the crown to permit new growth and better air circulation
To reduce the height of a tree
To remove obstructing lower branches
To shape a tree for design purposes
Once the decision has been made to prune, your next decision is whether or not to tackle the job yourself. In the case of a large tree where you want to remove big branches in the upper area of the crown, it may be best to hire experts. Large tree pruning, in particular, can require climbing and heavy saws or even cherry-pickers and chain saws.