Those climbing roses whose names start with 'Climbing' or 'Cl' are sports (genetic mutations of the bush varieties of the same name). They generally have a heavy spring bloom followed by scattered blooms throughout the season. The individual blooms on climbing roses can be of a finer quality and larger than those of the bush form. Climbing roses whose names are not prefaced with ‘Climbing’ or 'Cl' are bred by crossing two roses. They generally have a heavy spring crop followed by a better repeat bloom and usually a good fall crop of blooms with a few exceptions. A few seedling Climbing roses bloom only once and are so noted. Climbing roses are a diverse group with many different heritages, which makes this a wonderfully useful collection of roses. Large flowered climbing roses differ from Ramblers in that they have fewer, yet larger blooms (4-6 inches in size) and are not quite as vigorous. Being so diverse, they vary in winter hardiness, generally climbing roses are hardy zones 5 or 6 through 10 except as unless noted.