10/01/2026
Dreaming of Roses
Sun Damaged Roses
by
Barbara Carvallo Master Gardener,
Adams Broomfield County Rose Squad Member
and Consulting Rosarian
In my 60 odd years of gardening, this is one of the most difficult seasons of my experience. A level two drought, water restrictions, and excessive heat have contributed to the oppressive environment.
The summer of 2026 is the hottest Colorado summer in our 132-year climate history. NOAA has confirmed that our meteorological summer has broken records going back to 1895. In August we experienced record nighttime warming temperatures, 3 separate 4-day heat waves and record highs reaching well over a hundred degrees in some parts of the state.
In addition, according to the Colorado Climate Center, well below average precipitation this season put us in the sixth driest first 11 months in 131 years. Dry winter and spring seasons and low snow pack in the high country additionally limited water availability. An inability to fertilize regularly and a limited days a week watering scheme further weakened roses and made them more susceptible to sun damage.
The Rose Squad in Adams Broomfield County has received messages and photos throughout the season from people shocked by the appearance of their roses. In addition to shriveled flower edges, exposed canes displaying sun-bleached patches and crispy brown areas on leaves, our clients have often seen the following symptoms:
• New growth drooping, with defoliation if heat waves continue
• Smaller blooms
• Fades color
• Overall drooping of mature leaves
• Persistent and diffuse yellowing of leaves followed by the aforementioned crispy brown areas
• The most intense heat, particularly afternoon sun exposure, has produced dark discolored or reddish to brown patches on canes
• Cane die-back where stems have overheated has also been common
We have advised our home gardeners to make sure their mulch is spread 2 to 3 inches deep around the base of their roses. We advocate organic compost or wood chips. No rock, ever.
Providing shade where possible can be of great benefit. I have found the use of large tomato cages, placed around the rose and coved with a light shade cloth to be most effective, particularly with miniatures. On larger rose, stakes can be place around the rose to support the cloth.
Very selective pruning is indicated. Removal of burnt flowers and leaves that show 50% or more damage. I recommend leaving partially green leaves for the purpose of promoting photosynthesis.
Deep watering is advocated by the Squad. Three to five litters of water every few days applied at the base is recommended. Early morning or late evening is best to avoid the evaporation that can be so damaging. This can be done by hand where watering restrictions prohibit the use of sprinkler systems more than a couple of days a week or soaker hoses are not available.
Nothing is more disheartening than watching a lovely rose struggle and burn. During the course of this season, we have also seen the yield of fruit trees and grape vines severely reduced. Vegetable garden yield has been diminished, as has the production of other flowering plants.
I had thought that the warm dry winter and spring would seriously reduce the number of Japanese beetles. At least in the gardens I am familiar with – no such luck. It would seem that no matter what, that beetle will survive. There is a moral there, but I am too terrified to find it.
Well, because hope springs eternal, see you next season.
