Trimming involves removing excess branches to maintain a tree’s size and shape. When you trim a plant , the remaining foliage grows faster and thicker than if untrimmed . You should consider having tree trimmed annually or twice annually to control the look and direction of their growth . Regular trimming also ensures that troublesome growth is nipped in the bud before it becomes a problem or safety concern . Trimming can also help reduce overcrowding between plants planted too closely together.