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.
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.
Equipment / Tools
- Gardening gloves
- Protective clothing, shoes, and goggles
- Mini sledge (to pound posts)
- Chicken wire
- 4 Sturdy poles
- Twist-ties and twine
There are two basic steps you can take to prepare hydrangeas for winter: water them, and mulch them.
Two or three times in late fall, give your hydrangeas a deep watering. This will help them survive the desert-like conditions of a Northern winter, when water is locked up in the form of ice and therefore inaccessible to plants.
Apply mulch around them after the soil freezes (usually late fall in the North). Mulch not only acts as an insulator but helps retain needed moisture. Remove the mulch in spring when temperatures consistently stay above freezing again.
How to Build a Burlap Shelter
To go beyond this basic level of protection, provide your hydrangea with a shelter. Various types exist, but in our project we will build a burlap shelter.
Build the Frame
To create the frame around your shrub that will hold the burlap, drive four sturdy posts into the ground at each corner with a mini sledge, and stretch chicken wire between them on the outside of the posts. The chicken wire should extend at least 6 inches above the top of the bush.
Secure the Chicken Wire
Use twist-ties to secure the chicken wire to the posts.
Secure the Burlap
Tie burlap to the outside of the chicken wire using twine.
(Optional) Add Further Protection
Some gardeners go further and pack dried, shredded leaves loosely around the plant, after which they cover the top of the frame with another piece of burlap. Outside the frame, they insulate with bubble wrap.
Winter maintenance is minimal, but there are four things you can do for your hydrangea to go the extra mile:
- Regularly inspect the shelter to see if it has maintained its integrity and make adjustments as necessary.
- Take advantage of extended thaws. If the ground isn't frozen and the soil dry, irrigate the shrub.
- Check for pest damage and adjust your pest-control measures accordingly.
- If your shelter doesn't have a roof (or if the roof has caved in), check for any branches that have been damaged by snow or ice and prune them off.