Well I believe that spring has finally arrived as I write this article 10 days prior to publication. First, I received numerous calls this past winter concerning Deodar Cedars, Live Oak and Magnolia trees. Deodar Cedars are native to the Himalayan Mountains, which would lead you to believe they are cold tolerant.
In referencing Dr. Carl Whitcomb’s “Know it & Grow it III,” I discovered they are a zone 7b tree, which is marginal for here. My recommendation to homeowners is to wait and see how much die-back has occurred and what portion of the limbs will bud back out before making decisions on tree removal. I remember back in 1983 when we lost all of the Deodar Cedars in Oklahoma City due to a hard freeze in mid-December and it remained below freezing for more than two weeks. At that time I believed the death of the trees was not so much the cold, but the sudden temperature swing. We really did not have much of a fall that year. It was in the 80s on the weekend and by Wednesday it was 16 degrees. For the next 20 years no Deodar Cedars were planted.
As time passed, memories faded, and a new generation of landscapers entered into the industry and Deodars were reintroduced into our yards. We did not lose every cedar this past winter like we did in 1983, but we had enough loss and damage that it might slow down their re-introduction.
Live Oaks are another tree that we are growing on its northern limits as a zone 7 tree. I do not believe that we lost any Live Oaks, but the cold blasted a lot of leaves off the trees. Like the cedars, I am recommending homeowners take the same wait-and-see approach with these trees and see what and how much if the limbs bud and leaf out. I feel that we will see considerable die-back on some of these trees.
Magnolia trees are another tree that had a hard time this winter. They are a zone 7 tree that probably suffered more from the dry soil conditions than the cold weather. I would recommend that they be given Epsom salts at the rate of 1 pound per 10-feet of canopy spread and Ammonium Sulfate fertilizer at the rate of 10 pounds per 1,000 square feet. The most important time to fertilize Magnolias is right after the Bermuda grass goes dormant in the fall. When fertilizing in the fall, it gives the fertilizer the opportunity to sneak past the sleeping Bermuda and be available for the tree to recognize it the next spring. On Magnolia trees you only get that one initial flush of growth in the spring.
Other landscape plants that seemed to suffer from our cold dry winter were Boxwoods and Yews, which are hardier than the previously discussed plants. They are hardiness zone 5 shrubs. Both of these suffered damage in the summers of 20011 and 2012 from the severe heat. At that time there was considerable die-back. I was asked at the time by homeowners what they should do. I told them if they can stand the look of the plant through the fall and winter, wait until spring and see where the latent buds on the stem will develop and then prune back to the live area. Fortunately, with winter damage we will not have to wait months to determine the amount of damage to our plants. We will only have to wait a few more weeks.
As I drive around town, and in my own backyard, I have been seeing a lot of winter-kill in Bermudagrass lawns. For the most part, there was a good percentage of crown survival. However, in some lawns the stolons were completely killed. It will take most of the summer for the crowns to form new stolons to fill in the lawn. I would recommend on these lawns that a pre-emergent not be applied this year and to fertilize at — of the recommended rate, until the canopy of grass is restored.
RAY RIDLEN is a horticulture/agriculture educator for the Oklahoma County OSU Extension Service. He may be reached at 713-1125.