As winter sets in and temperatures fall, deciduous plants drop their leaves to help survive winter weather. However, conifers and broadleaf evergreens that retain foliage throughout the cold, harsh winter are highly susceptible to a type of damage known as desiccation or winterburn.
Plants pull moisture from the soil and release it as vapor through foliage. This process, called transpiration, works like a siphon and is continuous. That is, until the ground freezes. When water cannot be replenished, foliage becomes dehydrated. The combination of frigid temperatures, winter sun, and winds cause these dehydrated leaves to “burn.”
Antidesiccants are biodegradable compounds applied to foliage inhibiting moisture loss. Anti-desiccants provide a barrier over the leaf surface and are an effective way to help protect evergreen foliage from drying out during the winter.
Generally, winterburn damage is aesthetic, and will the plant will regenerate over time, however, antidesiccants are especially helpful to newly installed evergreens or exposed plants that may be vulnerable to harsh winter weather. More mature and established plantings are less likely to suffer from, but not certainly not immune to winterburn.
Antidesiccant products are not ideal in every circumstance. Plantings that best benefit from anti-desiccant applications include most broad leafed evergreen plants such as laurels, leucothoe, boxwood, rhododendrons, hollies, euonymus, and needled conifers such as yews, arborvitae.
We have found that antidesiccants are most effective when applied in fall and warmer periods throughout the winter. In Greater Boston it is best to apply treatments in fall and warmer winter days when temperatures are above 40 degrees. Often a second treatment is helpful, in January into February.
Winter can be quite harsh on your landscape and poses a particular challenge for your evergreens. Newly installed, young, and exposed broadleaf and needled evergreens are particularly susceptible to winter desiccation. Anitdesiccants are an easy way to help protect foliage and decrease the risk of winterburn damage.