I have a pine tree that I purchased 15 years ago and planted in my small backyard. It has split into two trees and is over 22 feet tall. Can a pine tree be trimmed down to about 10to15 feet and can I cut off one side without killing the other?

Yes, you can trim it down but will lose the shape of the pine tree; and yes, you can cut one off without losing the other, but then you are losing the 'personality' of the tree. Do you have a landscaped yard, or just a yard with the pine tree in it?

Pine trees do not resprout like deciduous trees do. You will have a flat topped tree that will grow wider but look pretty ugly.

Yes, you can trim it down but will lose the shape of the pine tree; and yes, you can cut one offno without losing the other, but then you are losing the 'personality' of the tree. Do you have a landscaped yard, or just a yard with Ithe pine tree in it?
No landscaped yard. Just a small yard with one tree in it. It's mostly cement and brick.ll

Cutting down a 22 foot tall pine tree to 10 feet is probably best handled by a professional tree crew. Ask the tree company for their opinion. Seek an arborist who can give you an opinion on the health and safety of the tree. Read a book or scan the internet - proper pruning is a mix of art and science.

Many pine trees exhibit a strong apical dominance. When you cut the top off the main trunk (the dominant apical meristem) of a pine tree, you cut off the leading point and the source of auxin, a plant hormone that inhibits other branches from growing as the main trunk. The result is bushy growth, as other growing points try to become the main trunk.