The Winter care and protection of roses concern the condition of the plants, the severity of the weather, and the methods and materials supplied by the gardener.
Preparation of the plant for Winter conditions is the first step. As early as August, new fast-growing basal shoots should be topped to check their rapid growth and promote the canes’ maturity.
Value of Mulches For Roses
Fertilizer and extra watering should be withheld after the first of September so that a minimum amount of new top growth is made before cold weather. Root growth, however, is desirable and may be encouraged by keeping the ground open as long as possible using surface mulches.
The same mulch tends to retard early growth activity in the Spring, thus preventing the severe losses which result from late Winter or early Spring freezes.
Related: Learn How To Grow Great-Looking Roses? Two Experts Share!
Causes of Rose Injury
Other than the late Winter freezes, severe cold occurring early in the season is most apt to injure the canes since they have had less time to mature and harden. Another point at which severe injury can result is during a period of low temperature following a prolonged midwinter thaw which has permitted growth to start.
A little insight into the mechanics of Winter injury may help the gardener deal with this annual problem in the rose garden.
As the temperature drops, ice crystals form in the intercellular spaces within the rose canes, exerting a crushing pressure upon the cells. This indicates the reason why tender, succulent growth has a very low resistance to cold.
Externally, excess moisture freezing on the outside of the canes is the cause of the splitting and shredding of the stems, which is so frequently observed at Spring pruning time. Injury at the union is apt to be fatal. The new shoots may weaken and die even when the damage appears slight.
Weather, A Problem
Protective measures might vary if the advanced weather forecast could be known for the season. Steady moderately cold weather would probably be no Winter hazard to most roses.
A loose deep covering of snow might be ideal if no alternate freezing and thawing occurred, resulting in ice freezing on the canes or around the crowns. During a very mild Winter, a rose planting might benefit most from a deep insulating mulch or litter.
The rather universally used 10″ soil mound covered with an insulating mulch layer has become standard practice because, in most cases, it gives the best form of protection, and variations from the average Winter cannot be predicted in advance.
Therefore, the mound should be applied in early Winter before deep-freezing occurs and should be removed carefully in Spring before growth resumes.
A windbreak is a helpful device since it reduces the whipping and breaking of the rose canes. It also has a moderating effect upon the location in case of sudden temperature drops.
Related: Keeping Roses From Winter