The end of January is approaching quickly. It seems as though winter has been upon us for many months, a typical Wisconsin winter. The cold and snow this year will certainly have an effect on your landscape. Frost moved into the soil early this year. The snow cover as insulation helps to stabilize the root systems for most of our plants, however, this also reduces the amount of soil moisture available to evergreen trees and shrubs. This can have an adverse affect on evergreens, especially those planted within the last calendar year. It will be important as soon as the thaw occurs to monitor your soil moisture around these plants. If there is a dry spring day it is recommended that you perform a deep watering for evergreen trees and shrubs.
Deciduous trees, even those recently planted, should not be adversely affected by winter. Deciduous trees are dormant during the winter and do not require much care. There could be some twig die back due to the weather and spring pruning should take care of this problem. Newly planted trees will also benefit from deep watering if we have a dry spring. The cold will most certainly cause problems for some of our deciduous shrubs. I recorded 21 degrees below zero twice at our house this winter. When spring approaches wait until new growth is seen and then cut plants, such as roses, back to the new growth.
The biggest problem we will see with our deciduous shrubs and spreading evergreen shrubs will be varmint damage. Below the snow, moles and mice will be nibbling away at the bark of the plants. They will eat the tender bark down to the wood, in essence girdling the twigs and branches they are feasting on. This type of damage will not be visible until spring. There is not much that can be done but prune affected areas back. Above the snow line the damage will be caused by deer and rabbits. Again, at this point, without trying to wrap your plants or cage them with hardware cloth or chicken wire, there is not much you can do until spring has sprung. Prune off affected twigs and branches. Typically, if a twig is showing white wood all around it will not survive.
Another casualty of the bitter cold can be spring flowering trees and shrubs. While most of the plants will not be affected, some flower buds (trees and shrubs that flower on last years growth) may be damaged or killed. Thankfully, this will only be a small percentage of the planted used in the landscape. On the upside, a cold winter like this can reduce the amount of insect pests we will see in the garden this year.