Boxwoods are traditional, dark-green shrubs. They are often used as border shrubs or as accent pieces. They can be pruned and clipped, or trimmed as topiaries. There are many different types of boxwoods, all of which have different growing conditions and slightly different appearances in foliage. Boxwoods can sometimes be tricky to grow, and they may encounter problems such as winter burn. This occurs when the boxwood absorbs water before a freeze, damaging the plant's tissues.
Wait until late spring to begin pruning the boxwood. Pruning earlier than late spring can make the plant vulnerable to cold snaps, which may cause more winter burn in the newly pruned areas of the plant.
Examine the boxwood to see how much damage it has sustained. Often, only the tips of the plants will be affected. The leaves on affected areas will appear white, yellow or brown. The bark in the problem area may appear to be splitting. Use a pair of pruning shears to snip off any small tips that have been affected. Hold off on snipping branches that have suffered more damage than just a burning of the tips.
Examine the bark of the plant. Starting at the tips of the boxwood, look for signs of splitting bark. Follow the split as far into the plant as it goes, then prune the branch off where the split ends, leaving only healthy bark.
Prune away any branches that have dark brown streaks running down the bark. Again, prune the branch as far down as needed to remove the entire brown streak.
Remove any dead leaves from the boxwood. It's important to remove as much of the winter burn as possible, as the plant will continue sending nutrients to the affected or dead areas, attempting to revive them. This can cause a slowing of the plant's growth or, depending on the degree of damage, may kill the boxwood.
Look at how many branches are affected with winter burn. If it seems like most of the plant has been affected, it's often best to completely prune the plant, cutting all the branches until the plant is only 1 to 1 1/2 feet tall. Boxwoods can recover from this severe pruning, but the process can take several years, depending on the variety of boxwood you have. If the boxwood is still relatively small, it is often more practical to replace the burnt boxwood with a healthy one.