Answer: Boxwood can show bare spots and yellowing as a response to winter damage or a pest or disease problem. Based on your description I am not certain which would be affecting your shrubs. If it is simply a matter of winter damage (the oscillating temperatures of spring this year were so stressful on plants!) then they should recover. Here is some information on potential problems and pruning to help you with removing any dead wood and working to improve their overall health.
Established boxwoods will fill in, assuming they are healthy, and correct pruning can help them do it fairly fast. It is usually better to work with established plants rather than replace them -- new plants take several years to become fully rooted and begin to fill in and look good.
I would suggest you consult with your county extension for help in diagnosing the problem, and based on knowing that, determine how to proceed.
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