Katherine Franklin of Bangor wrote to ask the following:

“How can I protect my rhododendrons from winter damage? I don’t know what variety I have, but at the end of every winter the shrubs look terrible, the leaves dead. Are there varieties that I could plant that would not do this?”

Katherine, the number of broad-leafed evergreen species that can survive our local winters without harm can be counted on one hand. Winter winds suck the moisture out of the leaves while the extreme cold turns the soil water to ice, making it impossible for the plant to replace the lost moisture. The result is predictable, an injury called “winter burn” or “winter desiccation.” If not too severe, plants may grow out of this injury, replacing the damaged leaves with new ones. But for several weeks in early spring, they are a sorry sight.

I observed rhododendrons of all types growing (or not growing) in the Lyle E. Littlefield Ornamentals Trial Garden at the University of Maine in Orono over several winters between 1998 and 2004. Some of these winters were particularly severe from the standpoint of

strong winds during periods of extreme cold. I learned that no evergreen rhododendron variety is completely resistant to winter injury in our area. However, there are varieties that are less susceptible.

Among the best are some varieties of Rhododendron catawbiense, the Catawba Rhododendron. The species grows wild on the dry slopes of the Allegheny Mountains from West Virginia to Georgia and Alabama. Since its introduction as an ornamental plant in 1809, hundreds of varieties, including hybrids, have been developed. Among the most winter-hardy is ‘Album’ with lilac-flushed buds that open to pure-white flowers with greenish-yellow spotting. Both ‘Boursault’ with lavender flowers and ‘English Roseum’ with flowers of light rose also perform well in our area, as does ‘Nova Zembla’, a variety with red flowers. There are others, but these are varieties likely to be available at local nurseries.

Also consider growing Rhododendron ‘P.J.M’ and related varieties including ‘Olga’ and ‘Black Satin’. Developed by Weston Nurseries in Hopkinton, Mass., this popular series of rhododendrons was developed for superior performance in New England landscapes. They have performed well in Littlefield Garden and elsewhere in our area, coming out of recent winters in good shape when sited in protected areas, sheltered from winter winds. In addition to excellent winter hardiness, they are known for their smaller, dark-colored leaves.

In our area, any broad-leafed evergreen should be planted in a site that is protected from prevailing winter winds. As added insurance against winter desiccation, you can surround your rhododendrons with a burlap windbreak. Before the ground freezes, drive four stakes into the ground to form an enclosure that is as high as the tallest buds, and then staple a sheet of burlap around the stakes. Take care not to let the burlap actually touch the leaves; you are creating a windbreak, not wrapping the plant like a mummy. Leave the top of the windbreak open to enhance air circulation.

I particularly recommend burlap windbreaks for any newly planted broad-leafed evergreen shrub that is still in the establishment period. Also, old rhododendrons that have been severely pruned will benefit from this added winter protection of new growth stimulated by the pruning.

We can grow rhododendrons in the Bangor area. A little more work in the garden this time of year will pay off in spring with an abundance of flowers and strong, healthy foliage.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley@shead.org. Include name, address and telephone number.