Expect to reduce moisture lost, don't expect miracles

Rhodies in the wind

If you have broadleaf evergreens in sites that are exposed to drying wind, or with root balls still too small to provide for the plant through winter, you might set up wind screens now, and/or apply anti-desiccant such as Wilt-pruf® or Moisturin® on a mild day.

Don't expect miracles...

...from these products. They block pores on the leaf surface so that less water can escape on mild winter days -- water that might be irreplaceable while the soil is frozen, and result in scorched leaf edges and dead twigs. Yet they can't do anything to make a plant more hardy. That's a result of genetics and health.

To increase a plant's hardiness

Put your effort into watering it well, if it's in a dry place, increasing its light if it's too shaded, or improving the drainage if it's a species such as Rhododendron that suffers when there's too much water and too little air around the roots.