The Agent's Corner Dec 1993

QUESTION: Now that winter is approaching how often should I water my roses, shrubs and trees?

ANSWER: Normally winter rain and snow are sufficient for plants in Cochise County. We can divide plants into two categories: deciduous, meaning those plants who lose their leaves and evergreens. When a plant loses its leaves there is little if any transpiration occurring. Photosynthesis has ceased in deciduous plants and water is required to make carbohydrates and oxygen. Winter rain and snow normally provide adequate moisture. Evergreens, on the other hand, have need of some water because their leaves will still do some photosynthesis if temperatures are not too cold. The general rule of thumb for watering evergreens in the winter is one third the summertime amount. This includes winter rain and snow which normally are adequate.

QUESTION: Should I prune shade trees and evergreen shrubs during the winter months?

ANSWER: Wait until February or later. Pruning is a stressful event for plants. Pruning is generally an invigorating process which not only causes buds to grow but also helps define a plant's shape and general health. Most deciduous perennial plants like trees and shrubs go through a process called winter rest. After losing their leaves in the fall they are incapable of growth, even under ideal conditions, until the rest period is completed. This occurs sometime in mid-winter to early spring depending on the plant species and climate. Rest is a biological strategy to ensure successful survival through the harshness of winter. With rest completed, plants can begin to develop which will lead to bud break, flower, leaf, and shoot growth. If you have ever wondered why crab apples or flowering plums do not bloom when shoots are cut and brought indoors, the reason is rest has not been completed.

Pruning of living plant tissue should only be started when rest is completed. That means mid-winter into spring. I have seen trees and shrubs pruned in December die because rest was not completed and the stress was too great. Pruning is invigorating and can cause bud growth in early winter which will die and deplete the plant of needed energy reserves to survive. Evergreens are normally pruned in the spring or summer. Dead branches and suckers can be pruned anytime. If there are further questions about pruning of specific plants contact the Cooperative Extension offices in Willcox or Sierra Vista.

QUESTION: Is it too late to plant bulbs for spring flowers?

ANSWER: No it is not too late. Spring flowering bulbs like daffodils, hyacinths, crocus, and tulips can be planted until you cannot work the soil. However, these bulbs must have six to eight weeks of cold temperatures (35 to 40 degreesF) to overcome winter rest. This process can be sped up by placing the bulbs in the refrigerator so that the cold requirement needed to complete rest will occur.

Rob Call
December, 1993