An old-fashioned favorite, hydrangea bushes showcase large globe-shaped purple/blue flowers throughout the summer and will continue to do so for many years if properly cared for during the winter months. Most hydrangeas do relatively well during cold-weather months and with a few winter care basics you can greatly determine the success and quantity of next year's blooms. The key to winter care of a hydrangea bush is to protect your plant prior to the first frost through the last frost the following spring.
Begin preparing your hydrangea bush for the winter by cutting out any dead or weak branches clear down to the base of the plant. Hydrangeas bloom on "old wood" so do not prune these branches back or you will not have many blooms the following spring. The best time to cut these branches is immediately following the last blooms in late summer, cutting off any dead flower heads.
Next you will need to insulate around your hydrangea to protect it from the cold temperatures which can also affect how many blooms there will be the following year. Place four 24-inch wooden stakes spaced evenly around the bush, approximately 1 foot out from the base of the plant. Wrap chicken wire around the outside of the stakes to form a cage, then secure by tying to the stakes using twine. Fill the cage clear to the top with pine needles or leaves to insulate the bush, being careful not to break the branches.
Water your bush as normal through September, two to three times weekly, then decrease to one time a week by October in preparation for the winter months. Do not water during the winter months.