COUNTRY GARDENING Effects of Oklahoma’s late-winter deep freeze on landscape plants By Trisha Gedon Oklahoma Cooperative Extension Service
t a time when many Oklahoma gardeners typically are planning their spring gardens, the state was dealing with ice and sub-zero temperatures for an extended amount of time. The deep freeze has many gardeners concerned about the health of their landscape plants, said David Hillock, Oklahoma State University Extension consumer horticulturist. “Permanent damage occurs to plants when conditions are severe, prolonged or when the temperature suddenly changes. We definitely experienced severe and prolonged cold temperatures,” Hillock said. “While gardeners are anxious to survey the damage and get started planting new plants, we need to put the brakes on just a bit because there is not much we can do right now,” he said. “We are in a waitand-see pattern because the real extent of damage will not be realized until plants break their winter dormancy and begin to grow – or in some cases, not grow. For the time being, keep the gardening shears and trimmers in storage.” As gardeners survey the landscape, some signs of plant damage are evident. Evergreens that were damaged by the freezing temperatures may be exhibiting brown or black foliage. Damage is most noticeable on broadleaf evergreen trees and shrubs, which may drop damaged 48 — Oklahoma Country
leaves. Plants such as hollies, southern magnolia, boxwood, loropetalum, aucuba, heavenly bamboo, autumn olive and some privets fall into this category. Hillock said most needled evergreens appear to have fared well with little to no damage, with the exception of deodar cedars and a few pines. Those trees already are exhibiting brown or yellow needles. “Typically, when a needled evergreen loses its leaves, the chance for recovery is pretty slim,” Hillock said. “However, in my experience as a horticulturist, I have observed cases in which deodar cedars
lose most of their leaves and still leaf out again in the spring. The key here will be if the buds responsible for new growth this spring were damaged in the freeze.” Gardeners may see brown, black, or mushy leaves and stems on their evergreen perennials. Most perennials will come back from their crowns and roots, especially if they were mulched or were covered with snow. Again, look for new growth in the spring before cutting back or planning for replacement. Gardeners who plant trees, shrubs and flowers that are considered hardy to
For many Oklahoma gardeners, damage to landscape plants was evident following the sub-zero temperatures that covered most of the state. Photo by David Hillock.