Although the symptoms are the same, there are many different shrubs that can suffer in the wintertime, particularly what are called the “broadleaf evergreens”. As the name implies, these plants have large flat leaves, not needles, that can easily lose water to evaporation in the wintertime. When the leaves lose water it must be replaced from the roots in order for the leaf to survive, but if the ground is frozen the plant cannot get any water from the soil. Therefore the leaf dies and any blooms that were on that branch will shrivel up and fall off along with the leaves. This is the most common cause of failure to bloom in rhododendrons.
What to do? Wrap your plants in the fall and leave the wrap on throughout early spring when the plants start to photosynth again. Leave any wrapping open on the top if your area receives a lot of snow. The snow is great for your shrub and will nicely insulate whatever it covers up.
Do not worry about sunlight! There is a common misconception that plants needs light in the winter in order to survive. Not only will plants not use sunlight-they’re dormant- but bright winter light will only “burn” the leaves and stems even more.
A gentle breeze only 5 mph will cause the plant to lose 200% more moisture than they would without the wind.
Plumstone 