June 2008

Grayson Kent Ted Mills Newsletter Leave a Comment

DEALING WITH HEAT STRESS IN ROSE BUSHES

By: Ted W. Mills, Master Rosarian and Judge

With Independence Day celebrations occurring all around, it is evident that summer has finally arrived. The sound of firecrackers and baseball bats cracking against speeding baseballs signals the arrival of hot weather in most areas of the ARS. To everyone whose hobby is rose growing, be ready for extra care during this time of year. July is here and August can’t be far behind. Unfortunately, far too many rosarians lighten up in their rose activities and head for the swimming pools. Believe the RoseDoc, a hot day is no time to lounge in the shaded hammocks of the nearest tree while your prized roses roast in the sun. Let’s talk about it.

To cope with heat stress that elevated temperatures cause, crafty rosarians know that irrigation is the best remedy available. Extra water is critically needed when the rose leaves droop and hang as limp towels from the bush. Truly, the bush is suffering. A quick shower, applied with the garden hose, will bring the plant’s temperature down swiftly. There are products such as ’wiltproof’, which offer some relief; however, a generous splashing of cool, clear water serves the purpose best. There was a time that the RoseDoc shied away from applying water to foliage, fearing it would produce the perfect condition for blackspot spore invasion. Common sense would let one know that failure to spray on a timely basis is the fault that allows blackspot to enter the rose garden. If the bush has been treated with an effective combatant chemical, there is no need to fear. Rinse the heated leaves with the cool water, allowing sufficient time for the water to evaporate before nightfall. Your roses will applaud the action. Repeat this water-cooling operation as often as the need for cooling exists.

It is essential to keep the root system cool and well-hydrated during periods of heat stress. In fact, their performance is enhanced if good hydration is furnished. Nothing pleases the plant more than a healthy drink of water. It is much more important than gorging the plant with fertilizer.

Perhaps one of the most effective ways to combat heat stress is to grow roses in pots. Many rosarians select this method since it gives them mobility of the plant. The RoseDoc has often wished he could simply roll the bush into a shady nook until the heat wave has passed. Roses on wheels so to speak. If pots are used, be sure the pots have ample drainage holes and are amply watered — usually more often than in rose beds. Good drainage is an absolute must to successful growing in pots.

Attending roses during heated periods gives the RoseDoc the opportunity to repeat the value of good mulching. Providing at least a two to four inch layer of shredded pine bark does much to keep the rose bush cool – especially the root system. The greater the temperature the thicker the mulch if one expects to control invading weeds. Always try to keep the mulching material moist. This action is cooling to the bushes.

Yes, firecrackers and marching bands alert us to summer. We all seem to enjoy the increased activities. But in our enjoyment let us not drop our guard. Elevated heat stirs the harmful critters to their damaging work. Heat by itself will decrease the size of the blooms and the garden just doesn’t have the beauty of spring nor the luster of fall. However, rosarians must step to the plate and help the roses survive the heat. Practicing some of the aids already mentioned should help in dealing with heat. Rosarians realize that sunlight is important and temperature aids vastly in plant growth, it’s the plants that suffer most when experiencing stress. Don’t head for the shade tree or swimming pool just yet. Attend to the woeful cries of the stressed bushes first. It is a good practice to perform this heated work while the cool hours of the day are present. Don’t procrastinate — take advantage of the cool mornings that often turn into heated afternoons. You may have to repeat this cooling treatment more than once per day. Double your cultural efforts so that the rose garden will experience minimal damage. You will be blessed for your actions and your roses just may take on a Happy Roses appearance.

A word of caution. Rosarians should minimize their chemical spraying during stressful heat periods (90 degrees and above) to avoid spray damage to the foliage.

Leave a Reply

Your email address will not be published.