Precautions to Circumvent Cold Damage

Homeowners hoping to safeguard their ornamental plants from winter injury can take certain precautions to prevent or reduce this seasonal hazard. Perhaps the best method to circumvent cold damage is by using plants native to your area, those imported from a similar climatic zone, or those that have become acclimated to our type of winter. When planted in a location suitable for their cultural requirements, they need little or no protection other than the natural, seasonal changes to reduce growth or bring about dormancy.

For plants that do not fit into one of the above groups, some measures will be necessary to prevent damage from cold. The following are some of the cultural practices and measures that may be used to give cold protection to ornamental plants.

Keep plants healthy, as they are more resistant to cold than diseased or unhealthy plants.

A fertilization program to produce a healthy plant aids in protecting ornamental plants from cold injury. In colder portions of the state, fertilize at one-third of the standard rate and in warmer sections two-thirds of the standard summer rate.

Watering plants thoroughly before cold weather may reduce cold injury. Wet soil is a much better conductor of heat than a dry one and a wet soil will lose its heat to the atmosphere much faster than a dry soil. Often cold weather is accompanied by strong winds as fronts move through. These strong winds may cause scorch and browning of the leaves at the tip and along the margin of the leaf due to rapid loss of water from these areas of the leaf. Watering of the soil may reduce leaf scorch by providing water for absorption by the roots to replace water lost from leaves by transpiration.

Avoid late fall pruning. Often new growth is induced by pruning and it is very susceptible to freeze damage. Prune plants after cold weather has arrived and plants are dormant.

Give physical protection by covering the upper parts of the plants and the root system area with plastic or other materials. Use stakes or make a frame around the shrub or tree to prevent the plastic from touching the foliage. Proper use of covers for plants usually reduced cold injury by reducing heat loss from the plant by radiation and conserves ground heat provided the cover extends to the ground. In case of a severe freeze, place an electric light bulb inside the covering. This will provide necessary heat to keep a plant from freezing. Be sure to remove all coverings immediately after the danger of a freeze has passed. This is particularly important, if the covering is clear plastic.

Certain cold tender and fast-growing species of plants may be partially root pruned in early fall to reduce vigorous growth and increase the maturity of the plant as protection against cold weather. Root pruning such plants in early fall reduces the amount of water and nutrients available and as a consequence, growth is reduced or almost stopped. When growth is reduced, the plant becomes "hardened" and is not so prone to cold damage.

If plants have been damaged by frost or freeze do not be in a hurry to prune them. Premature pruning may stimulate new tender growth that will be nipped by later cold. You may also remove live wood with an early pruning. Wait and prune in early spring as growth begins. At this time, you can better ascertain the extent of cold damage.