When it comes to tree maintenance, the terms trimming and pruning are often used interchangeably although they have different applications. Trimming is done to hedges and shrubs for aesthetic purposes. Pruning is done to trees and shrubs to remove damaged, diseased, and falling branches. Most trees and shrubs require annual pruning, while trimming should typically be done twice a year. If your yard contains tall trees and shrubs that are hard to reach or are located near power lines or other hazards, you might consider hiring a tree care professional.