Roses generally do not grow during the winter months; instead, they enter a state of rest called dormancy. This biological shutdown is a natural, protective response to the colder temperatures and reduced daylight hours of the season. The overall growth depends on the specific rose variety and the severity of the local climate, particularly consistent freezing.
The Biological State of Roses in Winter
Dormancy is a necessary survival mechanism for many perennial plants, including roses. It is triggered by shorter days and consistently cool temperatures, typically below 50°F. This state is a metabolic slowdown where the plant conserves energy for the coming spring. The rose’s internal processes are significantly reduced, and the movement of sap within the canes slows down considerably.
As the rose prepares for this rest period, it undergoes physiological changes to harden its structure against the cold. The most noticeable change is the shedding of leaves, which reduces water loss through transpiration during a time when the roots may struggle to absorb water from frozen soil. This leaf drop is a healthy sign of preparation. The canes become much firmer, and the cell sap thickens, a process that helps prevent the plant’s cells from rupturing if the internal water freezes.
While the rose is alive throughout the winter, it is not actively growing or flowering, meaning no new foliage or blooms are produced. Energy is stored within the roots and the base of the canes, ready to fuel vigorous growth when the conditions become favorable again. This period of rest is beneficial for the rose, as a lack of dormancy can lead to an exhausted plant that produces fewer blooms in the following season.
When Roses Might Still Grow or Bloom
The concept of a rose’s winter behavior changes in regions with mild winters, such as USDA hardiness zones 8 and above. In these areas, temperatures rarely drop below freezing, or do so only for short periods. Roses may remain semi-active or even continue to bloom sporadically because the environmental triggers for deep dormancy—consistent cold and short days—are not strong enough to force a complete shutdown.
Certain modern rose varieties, particularly those bred for continuous blooming, tend to resist true dormancy more than traditional Old Garden Roses. Instead of a complete rest, they may simply slow down their growth rate. If a mild winter features brief lulls in cold weather, these roses can exhibit opportunistic blooming, producing a few flowers during a warm spell. This is not the same as the vigorous growth seen in spring.
In some specific climates, like coastal California or parts of India, winter is the peak blooming season for roses due to the ideal combination of cooler temperatures and available moisture. Even in colder climates, a rose may be tricked into premature growth if a prolonged, unseasonably warm period occurs mid-winter. Such new, tender shoots are highly susceptible to damage when the hard freeze returns, which can compromise the plant’s health.
Essential Winter Protection
For roses in colder climates, generally USDA Zones 7 and below, proactive protection is required to ensure survival through freeze-and-thaw cycles. The main goal of winter preparation is to stabilize the temperature around the most vulnerable part of the plant, the crown, which is the area where the roots and canes meet. Fluctuations in temperature are often more damaging than consistent deep cold.
One of the most effective techniques is called “hilling,” which involves piling loose, additional soil around the base of the plant to a height of 10 to 12 inches. It is important to bring in extra material rather than scraping up the existing soil, as excavating around the crown can damage the roots. This soil mound insulates the graft union, which is particularly sensitive to cold damage on many hybrid rose types.
Applying a thick layer of organic mulch, such as straw or shredded leaves, over the hilled soil provides further insulation by trapping air and maintaining a more consistent soil temperature. This layer should be 2 to 4 inches deep and should be applied after the first hard frost, allowing the plant to enter dormancy naturally. For less hardy varieties, protective coverings like rose cones or burlap wraps can be used to shield the canes from drying winter winds.
Proper hydration is also a necessary preventative step, as roses can suffer from desiccation, or drying out, during the winter. Watering the rose deeply before the ground freezes solid ensures the canes and roots are fully hydrated. This moisture is held in the plant tissue, reducing the risk of damage from cold, dry air drawing the water out of the dormant canes.