Winter Watering should startup after October 31st. Give your plants a hearty drink and then again at least once a month during the winter. Water once or twice during November, December, January, February, and March if the soil is not covered with snow. Watering should be done when air temperatures are above freezing to allow the water to soak into the soil before freezing, and early enough in the day to allow water to soak into the ground by nightfall. It is a good idea to mulch plants with 3-4 inches of mulch to reduce soil temperature fluctuation and to keep soil moisture from drying out by the winter winds. Avoid saturating the soil.  Water when no wind or low wind speeds are expected. 
Basic Watering Information.