Winter cold and winds can be harsh on your landscape. Evergreen trees and shrubs maintain foliage throughout the winter months where they continue to lose moisture. With winter temperature fluctuations, moisture loss and the ground still frozen, transpiration occurs from the needles and leaves increasing water demand. If the roots cannot keep up with these demands the needles and leaves start to turn brown and die. Winter burn or desiccation is a dehydration of the plant due to water loss from the leaves through transpiration. This is caused by long dry periods of cold and thaw along with winter winds. Some broad-leaved evergreens such as holly, rhododendron, cherry laurel, skip laurel, mountain laurel, Japanese Skimmia, Leucothoe, Aucuba and Boxwood are even more susceptible to winter drying and long-term damage. An easy way of avoiding winter damage to plants is to apply an anti-desiccant spray to the upper and lower parts of the foliage before the temperatures drop below freezing or during a winter thaw.
WHEN TO APPLY: Apply anti-desiccant when the daytime temperatures start falling below 50 degrees (late fall/early winter). Apply when the temperatures are above freezing and there is no threat of rain or frost within 24 hours. (This tip applies to areas going into their winter season-temperatures dropping below freezing: 0 degrees Celsius or 32 degrees Fahrenheit.) Anti-desiccants are organic and break down under heat and light so it is recommended to spray again in late winter.
DANGERS: Be sure to read all directions on the label since anti-desiccants can cause photo toxicity on some narrow needled evergreens such as Arborvitae and Spruce that could cause more harm than winter burn. Spraying in freezing temperatures will do harm to the plant. Do not spray in freezing temperatures and allow time to dry before temperatures drop below 32oF or 0oC.
HOW OFTEN DOES IT NEED TO BE APPLIED: Sudden warm spells can trigger your evergreens to open their pores allowing for more water loss. If there is a winter thaw part way through the season it is recommended to re-spray your plants but only if the temperatures are to remain above freezing for at least 24 hours.
WHERE DO I PURCHASE ANTI-DESICCANT?: The most commonly used brands of anti-desiccant are Wilt-Pruf, Vapor Guard and Transfilm that can be found in nurseries and garden centers. There is a new brand of anti-desiccant on the market which requires only one application. Ask your landscape professional for more information.
HOW IT WORKS: Anti-desiccant spray is organic and biodegradable. It adds a protective waxy coating to the tops and undersides of the leaves of broad-leaved evergreens to help slow the process of transpiration which causes water loss and winter damage.
Author: Lee @ A Guide To Northeastern Gardening Copyright 2010. All Rights Reserved.