Canes are hardy to the tip. Indicates dieback of all canes to the snowline. Cane material below the snowline remained alive. Cane injury within a single plant can vary from none to complete kill to the ground. Closeup of dieback in the lower panel shows this variable injury pattern.
Every cane is killed to the ground.
In spring, new canes grow from plant s crown. The minimum air temperatures at the Arboretum and average snowcover 9 on a weekly basis for the winters during which injury was recorded can be seen in the figures below. Snowcover was minimal or absent during 1989-90. Many of the cultivars which typically exhibit the snowline pattern of hardiness died back to the ground in the absence of snowcover during that winter. This pattern of dieback to the ground was very common among the Old Garden Roses in the winter of 1989-90.