The hybrid perpetual class is truly a hybrid. This class came about from the crossing of Bourbon roses with roses from just about every other class. Hybrid perpetuals are a varied group and were very popular during the Victorian era. Some varieties tend to be less reliable in their rebloom ability, and there is variation in height. Most hybrid perpetuals are tall-growing, up to 6 feet or more. This makes them excellent candidates for use as pillar roses or along a fence. Most hybrid perpetuals bloom heavily in the early summer followed by an occasional bloom in the summer and a moderate bloom in autumn. Colors range from white to crimson with exceptional fragrance. Blooms often look like full-blown hybrid teas. Hybrid perpetuals are only moderately hardy in zone 5, needing winter protection or special siting for best survival. They also suffer occasionally from blackspot and mildew. Hybrid perpetuals also perform better after they have had a chance to establish themselves in an area.