Winter does not kill off blueberry plants as it does other plants. Highbush varieties of blueberries will survive temperatures down to -20 degrees F, according to North Dakota State University. Pruning the plant in the winter when it enters dormancy improves your harvests and the plant's growth for the rest of the year, but Oregon University recommends waiting until the third year of growth to prune. Keeping your blueberries healthy throughout the winter will give you more berries in the summer harvest season.
Cut any dead, diseased and decaying branches from the blueberry bush in January or February. Wear gardening gloves to prevent scratching your hands as you sort through the old growth to choose the branches best for pruning off.
Prune off any branches thinner than a pencil. Cut these tiny branches down to the spot where the branch begins to narrow.
Trim any old canes which do not produce berries back to the ground. Identify these oldest canes by their peeling, gray bark. Leave behind six to 12 canes with pairs of branches of the same age, as indicated by their diameter. For instance, if you have a three-year-old plant, leave two one-year-old branches, two two-year-old branches and two three-year-old branches intact for future growth.
Apply a 4- to 6-inch deep layer of organic mulch around the base of the blueberries. Choose organic mulches such as leaf compost or straw to provide insulation for the plant and to prevent cold damage and excessive drying of the soil.
Keep the blueberry plant well watered throughout the winter so the soil feels damp to the touch, recommends North Carolina State University; damp soil holds warmth better than dry soil.