Time of Year

• Master Gardener Center recommends trimming Darwin's barberry bushes after the bush has fruited. This is usually in the fall or winter. They recommend that Japanese barberry bushes should be trimmed in midwinter to late winter before the spring growth starts, and removal of dead wood should be during the summer months.
  
  

Trimming at Planting Time

• The University of Minnesota Extension suggests that trimming barberry bushes when you are planting them is important because it encourages the bush to establish a strong structure. This preventive measure is best performed while the plant is still in its dormant growing stage. Damaged or diseased branches should be removed. Thin branches for good spacing, and trim the bush to 6 inches from the ground.
  
  

Annual Trimming

• Trimming barberry bushes yearly is important to aid in better blooming and growth. The University of Minnesota Extension also recommends removing a third of the oldest branches to encourage new stems to grow. This will also prevent the need for major pruning jobs that occur when the trimming is not done regularly.
  
  

Reasons to Trim

• Trimming plants helps to remove branches that are diseased, damaged or growing improperly. People also choose to trim plants because of aesthetic reasons. Trimming plants can help to uphold safety around the plant, such as weather damaged limbs dangling or interference with stop signs or power lines. It also helps to encourage fruit and flower development .
  
  

Tools

• Pruning shears and lopping shears are good choices for trimming these bushes. As with all tools, keeping them sharp and well-maintained is a must to keep them working properly.