Roses are red, violets are blue, rose bush leaves are…red? Rose plants (Rosa, USDA plant hardiness zones 3 to 11) can indeed have red roses, but sometimes you also see rose leaves turning red. This is not necessarily a problem, but it can be in some cases. This red color is present because roses and other types of plants have pigments called anthocyanins. These help to determine flower, berry and leaf colors and are present in rose leaves and stems.
Rose Leaves Turning Red
Rose bush leaves can be a red or bronze color when they are young and growing, because of the presence of anthocyanins. They protect the leaves from UV rays, keeping them safe from the sun when they are most vulnerable. As the plants mature, they do not need this help so the anthocyanins and the reddish hue fade.
This red tint is not seen on all rose bush leaves; instead, it is more of a genetic trait. Different species of roses contain certain amounts of anthocyanins, likely dependent upon how much UV protection they need. So if the leaves have a reddish or bronze tint when they are young – as opposed to red spots or something else – it is probably just the anthocyanins doing their job.
Other Reasons for Red Rose Leaves
There could be a more sinister cause for rose bush red leaves. Problems that cause this coloration include rose rosette disease, a virus spread by the microscopic eriophyid mite. This presents with strange-looking, bright red foliage that resembles a witch's broom. The leaves are misshapen and tightly grouped together. The canes can also get thicker and thorny.
Another rose bush issue is rose flower proliferation, a growth disorder that causes a new bud to grow inside a flower that has already opened. This is also seen in other flowers like daisies and is likely a genetic mutation. It looks strange but is nothing to worry about; simply snip off the blossom if it bothers you.
More worrisome is black spot disease, and this is fairly common. The small spots start on upper leaves, have fuzzy edges and can then turn yellow, killing leaves and weakening the rose bush. Spot anthracnose is a little different; these black spots have grey centers and smooth edges.
Treating Rose Rosette and Spots
Rose rosette disease can be hard to cure, but you may be able to save the rose bush if you take immediate action. It usually starts on one cane first, without affecting the others. If you see it on just the one cane, you can cut it off completely, all the way down to the ground.
If the mites have not spread to the other leaves, the bush may survive. Sadly, if the disease has taken over the plant, it should be dug up, along with the roots, and thrown out. Do not plant any new rose bushes in that same spot.
Fortunately, black spot and spot anthracnose can be treated with a homemade spray that combines 1 tablespoon of baking soda, a few drops of liquid soap and a gallon of water. There are also many effective fungicides available to homeowners; look for solutions with neem oil, copper or sulfur. You might also want to try a dusting powder.