Red haw is a close relation of the more commonly grown Quebec hawthorn (C. submollis), which is found in garden hedges mixed in with the hedge hawthorn (C.grayana). Red haw and Quebec hawthorn can be distinguished by the more tree-like habit of the former, its greater thorniness, and also the larger number of stamens (20). Compared with C. grayana, red haw has larger, sweeter, pear-shaped red berries.
Winter hardiness is sufficient for the south of Finland, at least. The young trees at Mustila have been grown from seed collected in 1993. The parent trees were growing in the prairie zone, which has an extreme winter climate.