From our perspective, the primary threat of winter is not merely the cold, but the combination of freezing temperatures, drying winds, and fluctuating conditions. Our cells contain water, which expands when it freezes. This expansion can rupture cell walls, causing fatal damage to canes and roots. Furthermore, when the ground is frozen, our root systems cannot draw up water to replace the moisture lost from our canes through winter winds. This leads to desiccation—we essentially die from drought, not from the cold itself. Our survival strategy is to enter a state of deep dormancy, a suspended animation where metabolic activity nearly ceases. Your role is to support this dormancy and protect us from these secondary threats.
We cannot be rushed into dormancy; it is a gradual process triggered by shorter day lengths and cooler temperatures. To help us, you must stop applying high-nitrogen fertilizers by late summer. This encourages us to stop producing tender new growth that is highly susceptible to frost damage. Instead, a fertilizer higher in potassium (the last number in the N-P-K ratio) in early fall helps strengthen our cell walls and improves our overall winter hardiness. Please continue to water us deeply until the ground freezes. A well-hydrated plant enters winter far stronger than a stressed, dry one.
Our most vulnerable point is often the graft union, that knobby bump near the base of our canes. For many of us, this is where the desirable rose variety is joined to a hardier rootstock. If this union dies, the entire plant may be lost. Our root system, which is generally less cold-hardy than our canes, is also critical for survival. The goal is to maintain a consistently frozen soil environment, preventing us from prematurely breaking dormancy during a brief winter thaw. This is achieved by applying a thick, loose layer of mulch—such as shredded leaves, straw, or compost—over our base after the ground has frozen hard. This layer acts as an insulating blanket, keeping the soil cold and protecting our crown and roots from damaging freeze-thaw cycles.
Our above-ground canes are exposed to the elements. Winter sun can warm our south-facing sides enough to trigger cellular activity during the day, only for those same cells to freeze and rupture when temperatures plummet at night—a phenomenon called sun scald. Drying winds strip precious moisture from our canes that we cannot replace. For taller bush types, loosely tying our canes together with twine prevents them from whipping in the wind and suffering physical damage. For extra protection, especially for more tender varieties, surrounding us with a cylinder of hardware cloth or burlap and filling this cage with dry leaves or straw creates a microclimate that buffers us from wind and sun, drastically reducing moisture loss.
As the seasons turn, your assistance is needed once more. The danger of a hard frost often remains even as days warm. Removing protection too early can expose our tender new growth to a fatal freeze. The key is a gradual process. Begin by removing any dense, solid covers to improve air circulation as temperatures consistently rise above freezing. The mound of mulch around our base should be removed slowly, a little at a time, as the threat of hard frost diminishes. This gradual exposure allows us to acclimate to the increasing light and temperature at our own pace, ensuring we emerge from our dormancy strong and ready for a new season of growth.
