TOOELE — Keeping roses healthy and free from damage during the winter is a challenge. While no one can predict how bad the weather will be this year, most kinds of roses need help to survive unscathed.
The first advice I usually give is to select roses that are cold hardy. The list usually includes shrub roses, many old-fashioned roses and native roses, among others.
At the bottom of the list — in terms of cold hardiness — are the tree roses. Tree roses, more correctly called Rose Standards, were thought to have come from Victorian Europe, where they were common in royal rose gardens.
Tree roses never grow naturally. They are created by grafting the rootstock to the bottom of the central trunk. Then the desired flower variety is grafted to the top of the trunk to create the "tree." Typically, the central cane that the hybrid rose is grafted onto is 36 inches long and supported by a stake.
Although these beautiful grafted plants are appealing, double grafts with long exposed stems make them very susceptible to winter kill. The graft tissue and the long cane are susceptible to dehydration and need special protection during the winter.
Allen Whear, who lives in the home where he was born on Tooele's Main Street, has kept his tree roses healthy for many years. Whear's love of tree roses came from a neighbor in San Francisco, where he lived for about 10 years.
"My neighbor there grew tree roses, and I enjoyed looking at them," Whear said. "I thought that when I moved back to Utah I would like to have some beautiful tree roses. Of course, down there (San Francisco) roses were much easier to grow and care for. I liked them enough that (I) decided to plant them when I got back here."
Whear planted tree roses on either side of his front sidewalk. He selected several varieties, including Peace and Barbara Bush. He made the first plantings some 10 years ago and has been growing them ever since.
He admits he knew the roses would be harder to grow in Utah but did not know that winter kill might destroy them. After learning of their need for protection, he devised a simple process to keep the plants alive.
He places a wire cylinder around each plant this time of year and then fills it with leaves. "If I run out of leaves, I get a bale of straw to finish the job," he said.
"You have to prune the roses back so they fit into the cages. As they grow and bloom they get very large, and if you do not trim them, they do not fit inside the cages."
As you trim the roses to make them fit the cages, watch for signs of fungal diseases. Powdery mildew is the most common in our area. Prune off badly infected twigs and remove and destroy badly infected leaves. Whear doesn't take the leaves off his roses because they are usually free of harmful diseases.
"I leave the cages on until the end of February or the first of March," he said. He tills the leftover leaves and straw in other parts of his garden. "My neighbors say they know when winter is coming because I get the cages out and start filling them with leaves. They know that spring is coming when I start taking the cages off."
The question, of course, is whether the work is worth it.
"In 10 years I have never had any serious damage to my roses," Whear said.
While there are other ways to keep tree roses from winter kill, including digging them up and burying them or bringing them inside, Whear's is the easiest and most effective method I have seen for our area.
But most other types of roses in our area — the most popular being hybrid tea, floribunda and grandiflora — don't need as much protection. However, all these are susceptible to winter kill if the temperature drops to 10 degrees F. or below.
In addition, when temperatures fluctuate wildly throughout the winter, you are likely to lose many of these types of roses as they die above the graft. Even the root system, though normally cold hardy, will dry out and die from dehydration. Lack of snow cover, winter winds, intense sunlight and low humidity pull moisture from the soil. When this moisture is not replaced by rain or snow, roots dry out and die.
Mounding the plants with mulch or soil helps protect them. Pile mulch in a mound about 12 inches deep. Use wood chips, bark mulch or other loose materials. Avoid fine sawdust, loose leaves or other materials that pack down or blow away. Heavy mulches of soggy leaves or other materials can wreak havoc and increase the chance for disease.
If rodents are a problem in your area, use soil as the mulch material. Bring the soil in from another area of the garden so you do not damage the shallow roots of the rose plants.
Rose experts recommend that you place the mulch after the soil freezes. Mulches are not used to keep the plants warm but to keep them cold. It is usually the alternating freezing and thawing that kills the plants. Mulching after the soil freezes helps keep the soil cold, reducing the chance of premature bud break in the spring.
Larry A. Sagers is the Utah State University Extension horticulturist at Thanksgiving Point.