Winter Hardiness

Hydrangea macrophylla plants are winter hardy even in colder climates like Minnesota. However, in colder areas like Zone 4 they are not always reliably bud hardy. In this case the plant will come back but they may not flower. Therefore, some type of over-wintering protection is needed. The older the plant, the better your chances are for summer blooming. Abscised leaves from large plants falling in between the branches, affords some bud protection. Additional protection can be given by placing the plant near foundations, and using natural materials such as straw, leaves or mulch for insulation. Plants may die down to soil level in extreme cases but they come back again as the weather warms like all perennials. There are considerable differences between varieties as far as cold tolerance and consistent blooming. Recently there has been some attention given to varieties which supposedly bloom on new wood. Such blooming is not uncommon, all varieties can bloom on new wood if the winter has not been too severe. Until now, claims for varieties blooming consistently on new wood, have not been sustained. However, new breeding shows that there will be introductions of varieties which reliably bloom on new wood. Until then, winter protection is the best answer for summer blooming pleasure.