Crab apple trees are beloved by gardeners for their rounded, pleasing shape and gorgeous spring blooms. Many hybrids are available, with white or pink blossoms. For small yards, choose a dwarf or semi-dwarf tree. The fruit of crab apples is smaller and more bitter than regular apples, but makes a good jelly. Non-cooks can choose a non-fruit producing variety and avoid the mess of cleaning up crab apples every fall. Go lightly with the pruning. Crab apples need less pruning than other apple trees and can be damaged by too much of a good thing.
Cut out any dead or diseased branches. Dip your pruning tools in a solution of one part chlorine to nine parts water between cuts on diseased branches. This practice prevents the spread of diseases like fireblight. Discard these branches immediately.
Yank off water sprouts with your hands. These unattractive, soft branches grow vertically up from a lateral branch. They are sometimes the result of overzealous pruning and serve no purpose.
Remove branches that have grafted together or cross each other. For large branches follow this protocol to prevent tearing the bark: Make one cut on the underside of the branch about 12 inches from the trunk. Make a second cut all the way through the branch 14 inches from the trunk. Make the final cut cleanly through the branch, 1/4 inch past the collar. The collar is a small knob where the lateral branch joins the trunk of the tree. Cutting the branch flush to the tree creates a larger wound and promotes disease.
Renovate old trees slowly. You may be tempted to severely prune a neglected tree, but resist the urge. Never cut more than 25 to 30 percent of the tree's canopy in a given year. Start by removing dead branches and crossing branches as directed the first year. The second and third year, you can slowly remove large branches to shape the tree and allow light into the canopy.