Eglantyne, Photo By: Irene Hannestad
Unfortunately, there are no modern hybrid roses which can be considered drought tolerant or heat tolerant. That said, there are some techniques you can employ during our hot summers to reduce the watering needs of modern roses, thus reducing the heat stress they undergo.
- Reduce the fertilization schedule on your roses as they enter the summer months. This reduces their bloom schedule and reduces the amount of new growth put on during the heat of summer. Depending on which type of fertilizer you use, this means reducing the amount of fertilizer from two weeks to 30 days prior to when we expect our hot weather to sustain temperatures near 98F. For North Texans, we can expect these temperatures by mid-June. That should be your signal to start reducing your fertilizing until late in the summer. I prefer organic fertilizers, and fertilize heavily in late-February, then monthly until mid-May. I stop fertilizing until late-August.
- Consider using lighter-colored roses. Red, orange and lavender roses show heat stress more quickly than white, light-pink and pale yellow roses.
- When watering, apply deeply. Deep watering roses ensures moisture will penetrate down into the root zone where micorrhizal fungi and the root "hairs" maximize the surface area of the roots and provide the most efficient use of the water. Remember, too, that the root zone extends well down and away from the "drip line" of the rose. And if using roses grafted onto Fortuniana rootstocks, those roots will be closer to the soil's surface.
- To retain the moisture and moderate soil temperatures, ensure you have mulched heavily with 3 to 4 inches of shredded hardwood mulch.
- Apply antitranspirants. These waxy polymers help reduce the transpiration of moisture through leaves and stems. Products like Cloud Cover® or Wilt Pruf® or similar antidesiccants, sprayed per label directions, will help reduce the heat stress experienced by the rose.
- Replant your more heat-susceptible roses to the east side of your home or where they will receive protection from the hot, afternoon sun. When doing this, be certain they will still receive a minimum of 6 hours of direct sunlight. But that sun should be morning sun.
- Consider changing out some of your roses to those more tolerant of our southern heat extremes. Many of the so-called antique roses are more adapted to our heat and weather excesses here in Texas. These would include the Teas, Chinas, Hybrid Musks, Hybrid Perpetuals, Bourbons and many more Classes. Avoid using antique roses bred for colder climates such as the Kordes Roses and Rugosas.
By Mark Whitelaw, Kindly Provided by Laura Whitelaw