Wrapping tree trunks is a common, proactive measure aimed at protecting young, thin-barked trees from harsh winter conditions. This seasonal maintenance shields vulnerable woody plants from environmental stressors that can cause lasting damage to the bark and the conductive tissues beneath it. The process requires attention to timing and technique to ensure the protective measure remains beneficial.
Why Tree Wrapping Is Necessary
The primary threat that tree wrapping mitigates is a condition called sunscald, also known as southwest winter injury. This damage occurs on sunny winter days when direct sunlight warms the dark bark of a tree, particularly on the south or southwest side, causing the dormant cells to become active. When the sun sets or is blocked by clouds, the temperature plummets, rapidly freezing and killing the now-active cellular tissue in the trunk. This cycle of thawing and freezing results in sunken, discolored bark that eventually cracks or sloughs off, creating an entry point for insects and disease pathogens.
Wrapping also provides a physical barrier against hungry winter wildlife, such as rabbits, voles, and mice, which gnaw on tender bark when other food sources are scarce. If animals chew completely around the trunk, they effectively girdle the tree by severing the phloem layer, leading to the plant’s decline and death. The protective layer also guards against mechanical injuries caused by accidental contact with lawnmowers or string trimmers.
Essential Materials and Timing
The most common material for winter trunk protection is commercial tree wrap, often made of light-colored crepe paper or corrugated kraft paper. Light-colored materials are preferred because they reflect sunlight, preventing the bark from overheating and avoiding the sunscald effect. While plastic guards and burlap strips can also be used, the material must be breathable to prevent moisture accumulation, which can encourage fungal growth against the trunk.
The material should be applied in the late fall, typically around the end of October or early November, after the tree has entered its winter dormancy. Wait until the tree has shed its leaves but before the first hard frost arrives, ensuring the tree is prepared before temperature fluctuations begin.
Step-by-Step Wrapping Instructions
Begin the wrapping process at the base of the tree trunk, starting just above the soil line. Anchor the initial end of the wrap securely, but do not fasten it to the bark with tape or staples, as this can damage the living tissue.
Proceed to wrap the material upward around the trunk in a spiral pattern, similar to bandaging a limb. Each pass should overlap the previous layer by approximately one-third to one-half of the material’s width. This overlapping technique creates a shingle effect, allowing moisture to shed downward and away from the trunk. Keep the wrap snug against the bark to prevent slipping, but ensure it is not so tight that it constricts the trunk or impedes air circulation.
Continue spiraling the wrap up the trunk until you reach the point just above the lowest scaffold branches. Secure the end of the material using a strong, flexible tape, such as duct tape, or a piece of twine. Place the adhesive or twine only on the wrap itself, never directly onto the tree bark, which could be torn upon removal. The goal is to cover only the main trunk and not the branches.
When and How to Remove the Wrap
The protective wrap must be removed in the early spring, generally between mid-March and mid-April, once the persistent risk of severe freezing temperatures has passed. Leaving the material on too long is detrimental, as it can trap moisture against the bark, creating an ideal habitat for insects and fungal pathogens. Furthermore, as the tree’s girth increases during the growing season, the wrap can constrict the trunk, potentially causing girdling damage.
To remove the wrap, simply cut the securing tape or twine at the top and carefully unwind the material, inspecting the bark for any signs of damage or pest activity. The wrapping material should be discarded and replaced with fresh material the following fall if the tree still requires protection.