The barberries (berberis thunbergii autropurpurea) are a group of deciduous broadleaf shrubs that are a common element in landscape design. This is due to their purple or crimson red foliage, and their low maintenance. Over 25 cultivars of barberries exist. The most popular cultivars are the Crimson Giant, the Crimson Pygmy and Rose Glow. Often they are used as a specimen planting, in mass plantings, as borders, and as hedges (dependent upon the cultivar and its height and spread).
Prune away any damaged or diseased branches as soon as possible by making a clean cut at the point of the break or where it connects to a main stem. Where you make the cut will depend upon how it will affect the appearance of the plant. (Note: remove diseased branches completely.) You may do this at any time of the year. Winter can sometimes cause damage to shrubs due to the weight of ice and snow upon their branches. These broken or damaged branches must be pruned away in spring.
Inspect your bushes throughout the growing season and cut off any branches that may be interfering with the other plants in your garden bed. Also snip branches to control the desired size and shape. When you do this, you will be using two types of pruning procedures in tandem--"heading" and "thinning." When you use a heading cut, the cuts are made just above a side branch, and when you make a thinning cut the cut is made just above a bud. Which type of pruning procedure you use will depend upon the size and location of the branch that you are pruning.
When you cut above a bud, the cut should be about ¼ inch in front of the bud. This can be done in the spring while the plant is in its dormant stage or throughout the growing season without harming the plant in any way.
Trim to maintain a hedge (if you are using the barberries as a hedge). Use your hedge trimmers to cut the plant to the desired height and width. You can do this either every 8 weeks during the growing season. Or, you may select to just trim the hedge in the spring and the fall. Wear gloves and safety glasses while pruning a hedge.
Cut away old, woody canes that are located in the center of the plant. Do this in late winter while the plant is still dormant. The removal of old wood encourages the plant to produce new growth, which will give you a much denser plant. Due to the sharp thorns be sure to wear gloves.