October 2008
DEALING WITH HEAT STRESS IN ROSE BUSHES
By: Ted Mills, ARS Master Rosarian and Judge
The American flag in RoseDoc’s yard was fluttering in the chilly breeze as he arose on this October morning. Two squirrels were scurrying in search of food to be stored for the winter months ahead. Migrating butterflies were sapping nectar from the bluebell bush. Blue birds were driving away sparrows from their domain. All of this activity assured RoseDoc that fall is in the air and the work of a rosarian must not come to a halt.
Just a few short days ago a heat wave, accompanied by severe drought conditions, had caused raised leaves to hang limply on the rose bushes. Even the blooms were dwarfed in size as opening buds were speedily changing to fully open roses. Nothing seemed to go according to custom. But be not discouraged, the best time of the year for rose growing is upon us.
Every rosarian knows that the best blooms are produced in the fall months. However, this scenario does not happen by chance. The grower must step to the plate and give added attention to the things that produce good roses. Let’s talk about it.
Every time RoseDoc writes about rose culture the first thing that comes to his mind is water. Irrigation is the single most important ingredient in producing award-winning blooms. Rosarians sometimes fall into the trap that Mother Nature will surely water the plants during cold periods. This is not always the case. Inspect the soil in the rose beds and be sure it displays adequate moisture, particularly around the root system. The surface may be moist but dry roots bring on weak plants that sometimes perish.
Another important duty during the fall concerns the soil that surrounds the plant. Be sure that the pH factor is right for the bush. A reading of 6.2 – to 6.8 is considered safe with 6.5 being ideal. If the pH is above 7, it is too alkaline and needs to be lowered with the application of sulfur. However, in most cases here, the soil reading is too acid. Thereby, the application of dolomitic lime is the cure. Since lime works slowly, it is best to apply it in the fall. Such action will ensure the pH will be proper when spring arrives.
Inspect your garden and rid the rose beds of weak, unproductive plants that have not met expectations during the growing season. It is folly to spend time with weak specimens. Shovel prune them and replace in the spring with lively plants that perform well. As to plants that remain, check them for twiggy, dead or diseased growth and remove it before major pruning occurs in the spring. This action will lighten the load of the rosarian when spring arrives.
Some rosarians may already be planning to build new beds for additional rose plants. If this is the case, fall is the best time of year to perform this action. The components of the planting mix will have ample time to mellow and be ready for spring planting. Plan ahead and allow compost and organics time to experience chemical reaction. Optimum fertility is the result.
During the fall months is the best time to evaluate spray materials. Shelf life may have expired. This reduces the chemicals to ineffectiveness. It is a good practice to order just enough spray compounds to last one year. If it is determined that chemicals are satisfactory to carry over, be sure to store them in opaque containers that provide insulation to overcome freezing temperatures that often occur in winter months. Of course it is important to lock them to discourage tampering by children. Protect the spray materials from heat as well.
Many rosarians peruse rose catalogues in the fall hoping to purchase award-winning varieties. Often some inexperienced growers allow pretty pictures to deceive them as to quality of plants. If in doubt, always contact a Consulting Rosarian for advice on proven performers. This will save time and money.
The arrival of fall does not mean the rosarian can cease spraying. As long as foliage is present, the spray schedule must not be abandoned. Keep up the regular schedule until the bushes experience two hard freezes (28 Degrees F). To combat disease spores that may lurk and threaten the health of the bushes during winter, spray them with liquid lime sulfur – usually in January and then again just before major pruning time in the spring.
Now go out and enjoy this fall weather and don’t forget to smell the roses after you have performed your assigned rose culture duties.