How to Prepare Hydrangeas for Winter

Hydrangeas are among our most popular flowering shrubs. Most flower in summer, when the landscape is challenged to match the color display put on by spring. Even after they have finished blooming, their dried flower heads continue to add interest to the summer yard. But summer flowers only begin to tell the story of hydrangeas' contribution to the yard. There are hydrangeas valued for other features, including fall foliage, peeling bark to furnish winter interest, and even the ivy-like power to cover a wall.

Since they have so much to offer, it makes sense to put some time into giving your hydrangeas the care they need, so they have the best chance to be the star performers they're capable of being. One such care task may be to prepare hydrangeas for winter.

Before Getting Started

Why would a hydrangea need to be winterized? There are only two possible reasons:

• You're growing one north of the zone-range it's listed for.
• You must protect flower buds from winter's cold.

So you may not even have to winterize your hydrangea if you're growing it within the recommended zones. It depends on which type you have. Some hydrangeas bloom on old wood. This means that the flowers for any given year were formed on the prior year's branches (which is why you don't prune this type in fall). It also means that if winter's cold kills those flower buds, you'll lose flowers for the following growing season.

Even if a hydrangea does bloom on old wood, you don't necessarily have to do anything special to prepare it for winter. Many gardeners don't bother winterizing oakleaf hydrangea (H. quercifolia) or climbing hydrangea (H. anomala ssp. petiolaris). Not only are their flower buds rather cold-hardy, but these types often are valued more for other features than for their flowers (fall foliage/peeling bark and climbing ability, respectively). You wouldn't want to hide these features behind a shelter (in the case of a mature climbing hydrangea growing high on a wall, it would be difficult to furnish such shelter even if you wanted to).

Happily, some of the hydrangeas most valued for their flowers bloom on new wood (and many new types bloom on both old and new wood, which obviates the issue altogether). There's no need to winterize either smooth hydrangea (Hydrangea arborescens) or panicle hydrangea (Hydrangea paniculata).

That brings us to the one type of hydrangea that's a problem: the bigleaf (H. macrophylla). Bigleaf hydrangeas bloom on old wood, are valued mainly for their flowers, and therefore need winter protection for their buds.