I'm going to assume you're talking about pruning trees. When trimming a tree branch that you don't want to grow back, you need to cut the branch back to either another main branch or to the tree's trunk. Pruning should be done just outside the branch collar-the swollen, thick area at the base of each branch. Avoid injuring this area, as it is critical to healing the pruning wound.
Never leave a stub. New branches will grow back from around the edges. If you are worried about pests or disease, paint pruning wounds with tree salve (available at garden centers), tar or latex paint. For useful diagrams on making correct pruning cuts, visit the "tree care tips" section at the National Arbor Foundation's website. www.arborday.org
About The Author: Ellen Brown is our Green Living and Gardening Expert. Click here to ask Ellen a question! Ellen Brown is an environmental writer and photographer and the owner of Sustainable Media, an environmental media company that specializes in helping businesses and organizations promote eco-friendly products and services. Contact her on the web at http://www.sustainable-media.com