Roses are a popular and diverse landscape plant. While many of the roses that are classified as old garden roses are extremely tolerant of cold temperatures, others such as hybrid teas may experience considerable damage.
There are several different methods to protect roses from winter damage. The idea behind winter protection is to keep the plant uniformly cold and frozen all winter. This will prevent the plants from being damaged from the alternate freezing and thawing cycles we typically see during winter. Whatever method you choose, don’t begin protecting plants too early. Plants shouldn’t be covered until we have a hard killing frost (temperatures in the mid-20s or lower) and most of the leaves have fallen off of the plant. Temperatures should also have been in the teens for several nights. It’s important to remove any foliage or other debris that is diseased or might harbor disease to help reduce chances of infection next year. Additionally, some tall roses may need minor pruning to reduce their height. Pruning should be kept to a minimum, as most pruning will be done in the spring to remove dead and diseased canes.
The most common way to provide winter protection is the hilling method. This method uses a loose, soil and compost mix that is pilled or “hilled-up” around and over the plant about 10-12 inches deep. A variety of different materials can be used to make the hill, but the key is to be sure that the material is well drained. Wet and cold conditions are far more damaging than dry and cold. Soil that is used to “hill-up” plants should be brought in from outside the rose garden in order to prevent damage to the plants’ roots. After the soil mound has frozen, the mound can be covered with evergreen boughs, hardwood leaves or straw to help insulate and keep the soil frozen.
Another way to protect roses is to create a collar around the plants. Using hardware cloth or chicken wire, create an 18-inch-high ring around the plant. Then fill the collar with soil, again allowing it to freeze, then mulch with straw. The benefit of this method is that the wire holds the soil in place, preventing it from being eroded or washed away during the winter.
Some gardeners will protect their roses during the winter using Styrofoam rose cones. When using rose cones, make sure you don’t cover plants to early (use the same timing as previous methods). The cones also need to be well ventilated. Typically, cones don’t come with any type of ventilation holes in them, so cut four or five one-inch holes around the top and bottom of the cone. This will help prevent plants from getting too hot during sunny days. It’s also a good idea to mound some soil around the crown of the plant before putting the cone over it. Finally, once the cone has been placed over the plant, weight it down with a brick or rock to make sure it doesn’t blow away.
For more information on winter protection of roses, and roses in general, visit University of Illinois Extension’s Our Rose Garden website at https://extension.illinois.edu/roses.