Winter conditions pose several threats to vulnerable garden specimens, making proper protection necessary for certain plants. The most common injury is desiccation, or “winter burn,” which occurs when evergreens lose moisture through their foliage on windy, sunny days while their roots cannot absorb replacement water from frozen soil. Windburn also causes damage by physically tearing and drying out leaf tissue, especially on broadleaf evergreens like rhododendrons and holly. Wrapping is primarily a defense mechanism for these species and for borderline hardy plants susceptible to heavy snow load breakage or harsh winter winds.
Preparing Plants and Timing the Wrap
Plant preparation must focus on ensuring the specimen is well-hydrated before the ground freezes solid, which is a key defense against desiccation. Continue to water all evergreens thoroughly until late autumn, providing moisture until the soil is no longer workable. This deep watering allows the plant to enter dormancy with maximum moisture reserves, helping it withstand the drying effects of winter wind.
Mulching the root zone is another preparatory step that adds a layer of insulation to the soil. Apply a four to six-inch layer of wood chips or shredded bark around the base of the plant. Keep the mulch several inches away from the crown or trunk to prevent rot. This layer helps maintain a more consistent soil temperature, delaying deep freezing and reducing the chances of frost heaving.
The actual wrapping process should not begin until the plant has fully entered dormancy, typically after the first few hard frosts when temperatures consistently dip below freezing. Wrapping too early can trap warmth and moisture, potentially encouraging late-season growth susceptible to cold damage. It can also create an ideal environment for pests and fungal diseases. Install the protection in late fall or early winter, just before severe weather is predicted to arrive.
Essential Materials for Plant Protection
Effective winter protection requires materials that block harsh elements while still allowing air and moisture exchange to occur. Burlap, a heavy, woven fabric made from jute, is the preferred covering material because its coarse weave provides a permeable barrier against wind and sun. This breathability prevents the buildup of humidity inside the wrap, which is critical for preventing fungal infections and rot.
Horticultural fleece, also known as row cover fabric, is another excellent option that comes in various thicknesses. It is specifically designed to provide insulation without inhibiting air flow. For structural support, use durable wooden stakes, metal rebar, or sturdy fencing materials like chicken wire to create a rigid frame around the plant. This frame ensures the protective fabric does not rest directly against the foliage, preventing damage from wet material freezing against the plant tissue.
Avoid using solid plastic sheeting or non-breathable tarps as the primary covering material. Plastic traps solar radiation, leading to intense temperature fluctuations during sunny days. This causes the plant to warm up and then rapidly freeze again at night. This rapid freeze-thaw cycle is highly damaging to plant cells and promotes moisture condensation, which invites diseases. Any use of plastic should be limited to the exterior of a structure and only in conjunction with a breathable inner layer.
Step-by-Step Wrapping Techniques
The most effective method for protecting broadleaf evergreens and upright shrubs involves constructing a rigid, supported cage that surrounds the plant. Begin by driving three to four stakes into the ground around the perimeter of the shrub, ensuring they are placed a few inches outside the plant’s widest spread. The stakes should be driven deep enough to remain stable against strong winter winds.
Once the stakes are in place, wrap the chosen breathable fabric, such as burlap, around the outside of the stakes, encircling the plant two or three times for maximum wind deflection. Secure the fabric to the stakes using heavy-duty staples, twine, or zip ties, making sure the material is taut but not pressing against the foliage. While the sides should be fully covered, leaving the top partially open allows for some air circulation and light penetration, reducing the risk of overheating on mild days.
For container plants, a different approach is necessary because their roots lack the insulation of surrounding soil and are highly susceptible to freezing. First, group containers closely together against a sheltered wall or corner to benefit from mutual insulation and wind protection. Insulate the pots by wrapping the entire container with a thick layer of bubble wrap, burlap, or straw bales, securing the material with heavy twine. If possible, elevate the pots slightly off the cold ground using wooden blocks or bricks to prevent direct heat loss through the base.
Removing Protection and Avoiding Common Errors
Removing the protective wrappings must be timed carefully to avoid shocking the plant with an abrupt change in environment. The best time is typically in early spring, once the ground has fully thawed and the danger of prolonged hard freezes has passed. Wait until temperatures are consistently above 28 degrees Fahrenheit, as this minimizes the risk of a late-season freeze event.
It is beneficial to remove the wrappings on an overcast or cloudy day, rather than a bright, sunny one. This gradual re-exposure to full sunlight prevents the foliage, which has been shaded all winter, from being scorched or “sunburned.” Resist the urge to remove the protection too early, as a sudden return of freezing temperatures can severely damage buds and new growth.
A common mistake is wrapping plants too early in the fall, which can trap warm, moist air and encourage pests or fungal growth before the plant is fully dormant. Another frequent error is tying the branches together too tightly before wrapping, which can break brittle branches or restrict the plant’s ability to shed snow. Furthermore, utilizing non-breathable materials like plastic sheeting is detrimental, as it creates rapid temperature swings and excessive moisture buildup that can kill the plant through rot or sunscald.