Colder weather and higher winds keep reminding us that Ol’ Man Winter is just around the corner. Winter winds can cause your evergreen leaves and needles to dry out and die. You don’t have to experience this reality every season. Make this the year that you protect your evergreens.
Unlike deciduous trees and shrubs that go dormant in the winter, evergreens’ bodily functions simply slow down. Photosynthesis continues, just at a slower rate. However, water is necessary for photosynthesis to take place. During the growing season, plant roots absorb water and nutrients from the soil. In winter, when the ground is frozen, the plant roots can’t absorb water. But transpiration – the loss of water through the leaves/needles – continues. Losing too much water through transpiration causes affected branches to die and turn brown.
Under normal winter conditions, the leaves/needles reabsorb the transpired water and reuse it. Wind across leaves/needles, blows the transpired water off, leaving them high and dry. With no water for the photosynthetic reaction, the leaves dry out and die. In spring, you’ll see brown patches on your plants.
My favorite protection is to spray evergreens with an antidesiccant. This is a harmless, wax-like material that coats the leaves/needles, holding the water on them so the plants can reabsorb it and reuse it for photosynthesis.
I’ve used the term leaves/needles throughout to emphasize the need to apply antidesiccant to broadleaf evergreens like rhododendrons, as well as needled conifers. In fact, broadleaf evergreens may need antidesiccant even more than conifers. Leaves have more surface area than needles, and conifers have adapted better to the effects of winter winds.
Antidesiccant is available at garden centers in spray bottles. The leading brand is Wilt-Pruf. Hand spraying works fine for a couple of small shrubs but your hand gets tired quickly. An easier, more economical way to apply antidesiccant to a number of plants, especially tall conifers, is to have one of our Plant Health Care professionals apply it. They use a powerful backpack sprayer that reaches the top of most trees.