A dormancy process in which dormancy (sometimes called a dormant state) is induced, maintained or broken in a bud. Bud dormancy is a suspension of most physiological activity and growth that can be reactivated. It may be a response to environmental conditions such as seasonality or extreme heat, drought, or cold. The exit from bud dormancy is marked by the resumed growth of the bud.

Bud dormancy may precede dormancy of the whole plant.