When should shrubs be wrapped with burlap? After a frost?
Black Hawk County Iowa
Some evergreen shrubs, such as yews and boxwoods, are vulnerable to desiccation injury in winter. Evergreens lose considerable amounts of moisture through their leaves or needles, buds, and stems during the winter months. The loss of water is mainly due to strong winds and sun. Once the ground freezes, however, plant roots are no longer able to absorb water. Plant foliage that loses a large amount of moisture may eventually dry out, turn brown, and die. The damage to the needles/foliage is referred to as desiccation injury or winter burn.
To prevent desiccation injury, deeply water susceptible evergreens in fall if the soil is dry. Continue watering on a regular basis until the ground freezes in winter. Watering is especially important to evergreens planted in the last 2 to 3 years. Moisture loss can be reduced by erecting a shield or screen to deflect drying winds or shade plants in winter. A simple screen can be constructed with wooden posts and burlap. The protective shield or screen should be in place by late November.
Deciduous shrubs (those that lose their leaves in fall) are not susceptible to desiccation injury.