Sizzler of '80
Leonard O. Miller, DDS, Grove, Okla.
Heat is not the only dirty word to rhododendrons and azaleas. It's adjective, hot, is the really dirty word. This aberration of weather keeps the gardener from producing the garden of his or her dreams. It's the spoiler of our joys! The Southwest and particularly Oklahoma suffered in 1980 under the worst hot and dry weather in Oklahoma history. In 1932 similar weather drove Oklahomans to California at a greater rate than the gold rush. Few Okies left Oklahoma in the summer of 1980 because king size mattresses just wouldn't fit on top of Chevettes!
Northeast Oklahoma had 52 days, mostly continuous, of over 100 degrees. That type of heat puts a drain on city water supplies, lake levels, and water tables. The effect on landscape plants was devastating. 20 year old Norway spruces died, fields of white pines died and poorly planted or watered rhododendrons and azaleas died. In the natural forests old or weak oak, hickory and dogwood trees died. One does not have to cut live trees for firewood anymore because the woods are full of dead ones.
The effect of such weather on my garden was primarily on my small well that produces 5 gallons per minute and my sleep! I was able to connect to city water only to be rationed so that it couldn't be used for plants. There was insufficient pressure to run a lawn sprinkler from the city water. We watered around the clock from our well. Fortunately, I had moved most of my rhododendrons to a lath house and installed an automatic misting system in the spring. The misting system used little water and was turned on early in the morning when I was not watering other plants. All of the rhododendrons pulled through in great fashion setting some buds on the fifty plants.
The azaleas did not get such close attention. In our home garden we have about 700 azaleas which range from Kurume to Satsuki. The heat was tolerated by the plants but the floral buds did not set unless the plants were watered well. Public gardens in Tulsa and Muskogee all had good blooms because of careful planning of the watering needs of azaleas. These plants are planted in raised beds with large amounts of peat moss.
The heat of the Southwest is destructive to plants because of the high night time temperatures. It's not unusual for temperatures to stay at 80°F at night.
The plants that bloomed the best were the Gable azaleas. Most of the others did poorly except for the Kaempferi hybrids, 'Rose Greeley', 'Purple Splendour', 'Rosebud', 'La Roche' and 'Stewartstonian' all did well. We have 120 azalea cultivars. The one Glenn Dale that always stands out is 'Festive'. The native azalea that set bud was austrinum. On my soil azaleas are planted both in the ground and in raised beds. The only difference that I can tell is that the raised bed plantings require more water. The one sure thing I know is that the "Summer of '81" just can't be as hot as the sizzler of '80!