From our perspective, the process begins not with the first frost, but with the shortening daylight hours and the gradual cooling of the air and soil. We sense these subtle changes long before the ground freezes. This is our cue to begin the crucial process of hardening off. We actively slow our top growth, cease producing tender new leaves, and begin moving sugars and other vital compounds down into our root systems and lower canes. This internal preparation is the most critical step for our survival; no amount of external protection can help if we haven't completed this natural shutdown process. Please do not fertilize us late in the season, as this encourages the soft, new growth that is extremely vulnerable to freezing.
Our most vulnerable part during winter is not our canes, but the graft union—that knobby bump near our base where the desired rose variety is joined to the hardy rootstock. If this union freezes and dies, the entire plant, as you know it, will be lost, even if the roots below survive. Our roots themselves are also susceptible to freeze-thaw cycles that can heave us out of the ground, damaging our delicate feeder roots. The primary goal of your winterizing efforts should be to stabilize the soil temperature around our crown and roots, keeping us consistently cold and dormant, not warm.
You may not think of watering as a winter task, but for us, it is essential. As the soil cools and we enter dormancy, we still lose moisture through our canes (a process called desiccation). If the ground is dry going into a deep freeze, we risk severe dehydration, which can be as damaging as the cold itself. A deep, thorough watering in late autumn, before the ground freezes solid, provides a critical reservoir of moisture for our roots. Well-hydrated plant cells are also more resilient to cold damage. However, once the ground is frozen, watering is unnecessary and counterproductive.
After a hard frost or two, the most effective thing you can do is to mound a generous heap of fresh, dry soil, compost, or shredded leaves around our base. This mound should be about 10-12 inches high, completely covering our lower canes and the graft union. This is not primarily for warmth, but for insulation. It buffers us from drastic temperature swings, prevents the winter sun and wind from drying us out, and protects that vital graft union from killing frosts. Do not use soil scraped from around our base, as this can damage our surface roots; bring in fresh material.
In the coldest zones (USDA Zone 5 and below), or for more tender varieties, our taller canes may need additional attention. After mounding, you can loosely tie our canes together with twine to prevent them from whipping in the wind, which can cause damage at the base. For an extra layer, you can then surround us with a cylinder of mesh fencing filled with more insulating material like straw or shredded leaves. This creates a microclimate that minimizes wind scour and temperature fluctuation. For climbing roses, please gently detach our canes from their support, lay them horizontally on the ground, and secure them before mounding soil over the base and canes.
