Winter protection for your plants:

Wiltproof, an anti-desiccant will help retain the moisture in the leaf/needle for up to 4 months in the winter. Wilt-Pruf is a natural product derived from the resin of the pine tree. Since it makes no pesticide claims, it does not require registration with the EPA. It is an anti-desiccant which means it acts as a protective coating of the leaf or needle of the plant, substantially reducing water loss during high periods of stress. More from Missouri Botanical Garden link:

http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/pesticides/anti-desiccant.aspx

Hope this helps