It’s that time of year again. The temperature is falling steadily, soon to be below freezing and stay that way (except for the odd day or two) until the sun starts to thaw us out in late winter. During the dark, drab days of November through February, plants’ survival is tested by temperature and wind. Each alone makes heavy demands on plants, but in combination their effects can prove lethal, causing widespread damage and even death of plants, especially those not given some protection from the elements.
Weather related damage to plants is generally a result of either water loss or water-logged, poorly drained soil. More often than not, plants are introduced to an environment that is not optimal for them, where it is too windy, too wet, too dry, too shady, too sunny, etc. In a plant’s natural habitat, it can survive periods of stressful conditions, provided they are not prolonged. In a perfect world, plants would either have been placed in a suitable environment to begin with, or the environment would have been altered to provide for the plants’ needs. Plants that require well-drained soil generally do not do well in heavy clay unless the soil is emended, introducing drainage to move water away from the plants. Plants requiring moist soils will not do well in soils that drain readily without help, such as adding compost and/or installing irrigation. While it may seem that water would not be important to plants in winter because they are not growing and the temperatures are low, that is not the case. Plants lose moisture all the time through evapo-transpiration, defined as the loss of moisture from the plant which cannot be replaced quickly or in sufficient quantities to replace that which is lost through climactic conditions. The result of evapo-transpiration is a condition called die-back, where the ends of branches die due to lack of moisture. Die-back can also be caused by an inadequate supply of oxygen in poorly-drained soils.
Ideally, plants should have been originally located in an environment which would afford them the best chance of survival. But if plants are in a less-than-ideal spot, it is not too late to give them some protection from winter damage. There are some basic measures that will increase a plant’s chances of survival no matter where they are located.
Deep Irrigation. If it has been a dry fall, carry out a deep irrigation before the ground freezes. Plants will not undergo severe root death if the soil freezes in a wet condition.
Aeration. If it has been a wet fall, try to aerate the area thoroughly. If you have evergreen or deciduous trees in the lawn area, consider installing vertical tile midway between the trunk and the drip line of the tree (the outside limit of the crown). Alternately, you can dig three- to six-inch holes to a depth of twelve to fifteen inches and replace the soil with #8 pea gravel. The holes should be four to six feet apart. You can use these holes for feeding or irrigating in the future.
Wrapping. Plants such as arborvitae, boxwood, rhododendron and cedar benefit from wrapping to lessen the effect of wind damage.
Spraying. Spraying plants, especially evergreens such as boxwood, holly and arborvitae, with anti-desiccants will reduce loss of water. This should be done before the ground freezes and repeated throughout the winter when the temperature rises above freezing long enough for the spray to dry on the plant.
Netting. Plants that are susceptible to splitting apart from the accumulation of ice may be wrapped in bird netting to prevent breakage. Arborvitae are prone to this kind of damage.
Burlap Screens. The use of salt on the roads and highways is a constant challenge to plants. Salt spray can travel a mile from a heavily traveled highway, the distance dependent upon the force of wind and the obstructions the spray meets along the way. Burlap screens, used in combination with anti-desiccant sprays, have proven to be of value in protecting plants from salt.
Styrofoam Cones or Wire Cages. Plants such as shallow-rooted perennials and some roses are more susceptible to severe winter temperatures than other plants. Roses that are budded to a root stock such as hybrid teas, floribundas and grandifloras are particularly tender. Placing a Styrofoam cone filled with dry leaves over the plants affords them good protection. In place of the cones, create a circular cage of chicken wire and fill with dry leaves. Wrapping the cages with burlap increases the protection. (Note: Roses that are grown on their own root stock, meaning that they are propagated from cuttings, have a much better chance of surviving, and will regenerate to flower from the root if the rest of the plant dies. Budded roses can not regenerate flowering foliage from the root. Garden centers may not know which type of roses they are selling, so check the internet or ask your local landscape professional.)
Due to our currently mild weather, the ground has not yet frozen, so you still have time to undertake any of the above measures to protect your plants. You will be glad you did!