Protecting Plants From Cold Damage
While our temperatures typically stay above freezing in Wilson, gardeners need to remember the plants in the winter garden. Winter protection does not mean to keep plants warm, but to provide protection from damaging wind, snow and ice. It is the alternate freezing and thawing of the soil beneath the plants and heat from the sun on very cold days that are the main culprits causing winter damage.
Protection should be offered to evergreen plants by reducing water loss. Plants transpire water through their leaves. Evergreens continue to lose water during the winter and need moisture to be taken up by their plant roots. We are experiencing a wet winter so far so evergreens should be fairly well. Gardeners are more conscious of watering shrubs during the summer months and often watering is neglected during cold weather. These plants continue to transpire water but during the winter draw moisture from living cells. If too much water is transpired the cell dies. Consequently leaves brown out and die. High winds and warm sun on cold days result in a higher rate of water transpiration. Protection could be offered by planting susceptible plants in a sheltered location and providing additional water during dry periods or prior to expected hard freezes.
Foundation plantings are often injured by ice and snow falling from the roof on their frozen branches. It is sometimes necessary to construct a temporary shelter for shrubs in this situation. Wide tape or cloth can simply be wrapped around an evergreen to prevent broken branches. This is quite helpful to boxwoods and arborvitaes. If branches are bent over by ice or snow it is advisable to wait a few days before pruning. Often branches will recover to a degree of satisfaction on their own–so don’t be hasty to prune.
An additional layer of mulch is usually recommended during winter months after the first freeze. Mulches will reduce water loss from the soil thus aiding in transpiration, and also reduce ‘heaving’ of the soil as the soil freezes and thaws.
To protect plants from cold damage: 1) plant only varieties that are hardy to our area. 2) Locate less hardy plants in the highest part of the yard. Cold air settles to the lowest part of the yard. 3) Protect plants from cold wind. A fence or tall evergreen hedge of trees or shrubs gives good protection. 4) Shade plants from direct winter sun, especially early morning sun. Plants that freeze slowly and thaw slowly will be the least damaged. The south side of the house with no shade is the worse place for tender plants. 5) Stop fertilizing plants with nitrogen in late summer. Let them “harden off” before cold weather. 6) A covering of plastic can be used as protection. Build a frame over the plants, cover with plastic and seal plastic to the ground with soil. Shade plastic to keep temperature from building up inside. Plastic traps moisture and warm air as it radiates from the soil. It also knocks off cold wind. Be certain not to allow the plastic to come in contact with plants or it will burn the foliage. Knowing how and when to offer first aid to an ice, snow, or wind-damaged plants will often save the plant from future decay and possible loss.
The Wilson County Extension Master Gardener Volunteers are waiting to answer your gardening questions this winter on Wednesdays from 1-3 PM and via email at firstname.lastname@example.org.