Rosarians understand that while growing roses in the desert is challenging, it’s also quite rewarding. Believe it or not, many varieties that don’t normally bloom twice a year will do so in our Scottsdale climate. Overall, the trick to growing better roses in Scottsdale is to choose varieties that have proven their heat tolerance. These include popular roses such as “Peace,” “Julia Child,” and a climber named “Sally Holmes.” Since we’re heading into another hot, dry Scottsdale summer I thought this would be a great time to share some tips from local rose experts.
A 3 to 4-inch layer of mulch spread around the rose bush (placed 6 inches away from the plant) will help conserve soil moisture and insulate the plant’s roots from the heat. In fact, “The mulch will keep the roots 10 to 15 degrees cooler then the air temperature,” according to Leonard Trubisky, a local rosarian, writing for the American Rose Society.
Yes, roses require deep irrigation. The good news, however, is that they’ll bloom even when those irrigations are sporadic. A good way to determine how deep to water the rose is to measure what you’re giving it now and then adjust to its needs.
Push a piece of rebar or something similar into the soil after you water the rose. It will stop when it hits dry soil. Continue watering until the rod can be easily inserted into the soil to a depth of 2 feet. Don’t water again until the top 2 inches of soil is dry. Watering lightly and frequently causes the roots to remain shallow where they are more apt to be damaged by the heat.
During windy or particularly hot periods, check the soil’s moisture content daily. According to Trubisky you may need to water your roses three or more times per week in the summer.
To get the aforementioned second bloom you’ll need to consistently deadhead the plant throughout April and into early May. Since we’re well past that now, file the info away for next year.
For the new rose grower, deadheading simply means the removal of spent blooms. Leave them on the plant and it will think the season is over and begin producing rose hips – the seed pod. Cut the stem back to a cluster of 5 leaves and make the cut just above that cluster (so that it remains on the plant).
It’s important to use caution when fertilizing your roses when the temperature amps up in the summer in Scottsdale. Cut the rate to half what you normally use when you fertilize in June, July and August. Fertilize early in the morning and water the soil both before and after you apply fertilizer to prevent burning the plant.
Of course these are the basics to growing better roses in Scottsdale. The Mesa-East Valley Rose Society has a list of the best roses to grow here on its website. They also have a page full of links to articles about everything from when to do what to bugs and diseases. Find that here. Finally, the University of Arizona Tucson’s cooperative extension website offers a handy guide to growing and caring for roses in Arizona.