Protecting shrubs from winter weather is a proactive measure for maintaining landscape integrity. Winterizing involves physically covering susceptible plants to mitigate damage from environmental stressors. Properly preparing and covering these plants ensures they survive the dormant season, protecting the financial and aesthetic investment in your outdoor space. This preparation is more effective than attempting recovery after injury has occurred.
Understanding Winter Damage and Vulnerable Shrubs
The primary threat to unprotected shrubs is desiccation, often called winter burn. This occurs when frozen soil prevents roots from absorbing water while dry winter winds and sun pull moisture from the foliage. This is particularly damaging to broadleaf and needle evergreens. Mechanical damage is also a risk, as heavy snow or ice loads can break branches and alter the plant’s structure.
Shrubs that are newly planted, marginally hardy for the climate zone, or situated in highly exposed locations are the most susceptible. Sudden temperature fluctuations can cause frost heave, where repeated freezing and thawing cycles lift shallow-rooted plants out of the soil. Physical covering is required to create a stable microclimate and shield these vulnerable plants from direct exposure.
Essential Pre-Covering Preparations
Before installing any physical cover, preparing the shrub and its surrounding soil is paramount. Deep watering is necessary until the ground freezes solid, providing a reserve of moisture to counteract the drying effects of winter wind and sun. This pre-freeze irrigation is the most significant step in preventing desiccation damage.
Applying a fresh layer of organic mulch, typically two to four inches deep, helps insulate the soil and maintain a consistent temperature. This insulation minimizes the freeze-thaw cycles that lead to frost heave, protecting the root system. Only minimal structural pruning should be performed now, removing weak, diseased, or broken branches. Major shaping should be delayed until spring to avoid stimulating new growth vulnerable to cold.
Step-by-Step Covering Techniques
The most common technique for smaller, individual shrubs involves wrapping them with breathable burlap fabric. When using burlap, avoid cinching the material tightly against the foliage, which can trap moisture and promote fungal growth. Instead, the burlap should be loosely draped and secured with twine, allowing air circulation around the plant.
Ensuring the burlap does not directly contact the needles or leaves helps prevent abrasion caused by wind movement. The wrapping should extend slightly beyond the drip line. The top can be left partially open or tented to allow light penetration and air flow, shielding the plant from wind and sun while permitting necessary gas exchange.
Using Protective Frames
For larger or more structurally complex shrubs, building a protective frame or teepee structure is often the better solution. This involves driving three or four sturdy stakes into the ground around the plant and then securing a wire cage or wooden frame to the stakes. This framework prevents heavy snow from crushing the branches.
Once the frame is established, a covering material such as burlap or specialized porous winter fabric is wrapped around the exterior of the structure. The frame maintains a crucial air gap between the protective fabric and the foliage, which acts as an insulating pocket. This method is effective for plants like upright junipers or arborvitae that are prone to splaying under ice load.
Constructing Windbreaks
For long rows of shrubs or highly exposed foundation plantings, constructing a solid windbreak may be more practical than individual wrapping. Barriers made from snow fencing, plywood, or woven screens can be positioned on the side of the prevailing winter winds. These barriers reduce the velocity of the air flow, significantly mitigating the rate of moisture loss from the plants.
Timing the Installation and Spring Unveiling
Installation should only occur once the ground has frozen solid, typically in late fall or early winter after several hard frosts. Applying covers too early can trap excessive moisture during warm periods, encouraging mold and mildew growth. Waiting until the soil is fully frozen ensures the plant is dormant and less likely to be stressed.
Removing the covers in the spring requires equal attention. Covers should be taken down gradually once the threat of severe, prolonged freezing temperatures has passed, corresponding with the spring thaw. Remove the covers on an overcast day to prevent sun shock or scalding damage from sudden exposure to bright sunlight.