Fall is a time when most plants go dormant and a good time for the homeowner to help protect plants from the cold days ahead.
The physiological changes that occur within a plant as it goes dormant are complex and not fully understood.
It is known, however, that different plant parts on the same plant develop different degrees of cold hardiness.
Roots and fruits have little ability to acclimate and develop cold hardiness; while leaves, stems and buds can acclimate readily.
The fact that roots are not able to develop cold resistance provides the basis for winter mulching.
Three to 5 inches of a mulching material such as pine straw, pine bark or fall leaves will help insulate roots from freezing temperatures. Plants growing outdoors in containers should be taken indoors or protected from freezing temperatures.
The degree of hardiness a plant achieves is affected by a number of factors including age, vigor, cultural practices and heredity. Plants stressed by insects, diseases or summer drought will be more susceptible to cold.
When a severe or sudden freeze is forecast and you know there are plants in your landscape susceptible to the cold, here are a few suggestions for helping them survive the ordeal:
• Old sheets or blankets can be thrown over plants to help trap and hold in heat from the soil and to protect them from the cold wind. Place the covering on during the late afternoon and remove it by mid-morning the next day.
• Make certain all plants are well mulched. If 2 or 3 inches of a mulching material is already in place and a severe freeze threatens, add 2 or 3 more inches for extra protection.
• If possible, continue watering throughout the winter, at least once every two weeks if it doesn’t rain.
Our most severe freezes occur when cold drying winds from the northwest combine with freezing temperatures.
Plants can easily dehydrate if moisture is not present for the roots to absorb.
Water also helps trap and hold heat in the soil.
• Avoid icing over plants. Spraying plants with water during a freeze to create a thick coating of ice is not a recommended practice for the home landscape. A heavy accumulation of ice can cause limb breakage and severe physical damage to trees and shrubs.
Also, during a severe freeze with high winds, ice will evaporate and actually pull heat from the plant causing the internal temperature of the plant to fall far below 32 degrees.
Clark Beusse is the Dawson County extension agent. For more information, call (706) 265-2442.