I recently visited a neighbour’s home whose garden included a great hydrangea shrub without the blooms.
Its foliage was remarkably green and robust, and yet there was not a bud in sight. This is a particular complaint with what’s known as “the big leaf” variety of hydrangea: Hydrangea macrophilia. These are the ones whose flowers are either pink or blue depending on the pH of the soil.
Flowers on these hydrangeas are produced on old wood. In our climate (Zone 3 to be safe, but pushing to Zone 4), the wood on this hydrangea dies back to its base and, come spring, produces new cultivars: new wood. Flowers of this variety simply don’t grow on new wood.
Any hydrangea could fail to produce a decent bloom. They key is to overwinter it carefully.
According to the Farmer’s Almanac this year, we’re in for another doozy. What you want to do is to cut away the dead wood. This is characteristically hollow. The old wood still has a green centre and should be protected.
But here’s the trouble: Since the winters are harsh, any exposed wood could be killed by the elements if not carefully covered. Cut them back to about a third of the plant.
Once the ground is frozen, mulch the crown with dry leaves, trying to cover the wood as much as possible. You can wrap them, but I never do. I let the snow act as an insulator.
If your hydrangea is exposed and vulnerable to harsh winds, and snow provides scant cover, think about protecting it with both mulch and wrap. Note, as well, that you can wait to cut them back until spring as the old blooms act as winter interest.
You’ll be able to see the dead wood much more easily and reduce the risk of pruning back the old wood by accident. The key is protection.
You might also consider the soil. An abundance of nitrogen (lawn fertilizers have it in spades), will produce only lush leaves. You’ll need phosphorus (bone meal) to balance it out and get the blooms you desire.
Another point, “my Annabelle is flopping to the ground”, is an article unto itself. Because we so readily cut back the wood, those stems never get a chance to thicken and thus, will never get wider despite the profuse blooms; thus, a “floppy mop head.”
Again, try pruning the old wood only minimally. Instead of a third, try a half. Many gardeners will plant more than one Annabelle; three of them together will eventually “knit” their stems and get stronger that way.
If you are just planting an Annabelle, try planting it in front of a gate or a fence, so that it is supported. You could also plant them behind another, sturdier evergreen, like a yew or a cedar. These will also provide some stem support.
Hydrangeas are worth the trouble. Their exciting blooms add late season interest to your garden and provide food for bees and butterflies alike.
Anne Boulton is an avid gardener who lives in Sudbury. Visit her blog at greenbootsgardens.tumblr.com or contact her at firstname.lastname@example.org.