Most rose bushes are perennials, meaning they live for more than two growing seasons and return each spring. Successful return depends heavily on the specific type of rose, the climate, and the care it receives before and during winter. Proper preparation for the non-growing season is the most important factor in ensuring your rose survives the cold and produces new growth when warmer weather returns.
Understanding the Perennial Life Cycle
Perennial plants, including roses, survive the winter by entering a state of reduced metabolic activity called dormancy. This is a natural adaptation to seasonal changes, triggered by decreasing daylight hours and falling temperatures in the autumn. During this phase, the plant shuts down much of its above-ground growth, conserving energy to ensure the survival of the root system and the lower cane structure.
For a rose, the above-ground canes may appear lifeless, but the root crown, located just below the soil surface, remains viable and protected. Inside the stems, cell sap thickens, increasing the cold hardiness of the plant tissue. This allows the plant to withstand freezing conditions.
When temperatures consistently rise in the spring, the plant breaks dormancy, and new shoots emerge from viable buds, or nodes, on the surviving canes and from the root crown. The ability to regenerate from a protected root system is the defining mechanism that permits a rose bush to return year after year. Modern re-blooming roses may not enter the deep, true dormancy of old garden varieties, but they still slow their systems significantly to survive the cold.
Essential Winterizing Techniques
Ensuring a rose’s return often requires the gardener to assist this natural process, particularly in colder regions. A primary technique is to stop fertilizing and reduce watering in late summer or early fall, which helps the rose slow its growth and harden its canes for winter. Actively growing, soft canes are much more susceptible to frost damage and desiccation than mature, hardened wood.
After the first few hard frosts, and before the ground freezes solid, the most important step is mounding, or “hilling,” soil or compost around the base of the bush. This creates a protective 8 to 12-inch hill that insulates the vulnerable graft union or root crown from extreme cold and freeze-thaw cycles. For grafted roses, protecting the graft union is paramount to prevent the loss of the cultivar.
Taller hybrid tea or floribunda canes are often pruned back to about 18 to 36 inches to minimize wind damage and cane desiccation during winter. In zones below USDA Zone 6, additional protection, such as surrounding the mound with a cylinder of chicken wire and filling it with non-compacting mulch like pine needles or straw, provides an extra layer of insulation against the severe cold.
Differentiating Rose Types and Hardiness Zones
The likelihood of a rose returning strongly depends on its genetic makeup and the local climate, typically defined by the USDA Hardiness Zone system. This system identifies the average annual minimum winter temperature, which determines a rose’s innate cold tolerance. A rose rated for Zone 7, for instance, will require substantially more protection in Zone 4 than a rose bred for Zone 4.
Rose plants are primarily categorized as either “grafted” or “own-root,” a distinction that affects their winter survival. Grafted roses consist of a desired top variety budded onto a more vigorous rootstock, which creates a vulnerable bud union susceptible to freezing. If the top part dies, the surviving rootstock may send up suckers that produce a different, undesirable flower.
Own-root roses, which grow directly from their own cuttings, are significantly more resilient in cold climates, especially in Zone 6 and below. If the above-ground growth is killed back completely by the cold, the plant will still return true to type from its surviving underground root system. Shrub roses and many Old Garden Roses are generally the most cold-hardy types, often requiring little more than a simple layer of mulch in many zones, unlike the more temperature-sensitive Hybrid Teas and Floribundas.