It’s July, and that means the spring and early summer blooms have long faded, giving way to the workhorses of midsummer, and hydrangeas are one of them. Beloved by many, they’re a garden staple across Cape Cod and much of Southern New England.
Now’s a great time to delve into these beautiful shrubs. Most are familiar with the popular Nikko Blue mophead variety. These big blue flowers are so prized by so many gardeners, but they actually have plenty of downsides. This isn’t a call to dig them all up. It’s just worth noting a few things about this summer mainstay. I’ll get to some alternatives shortly.
Nikko Blue blooms on what’s called old wood. In other words, the blooms for next summer are being set right now, over the next couple of months. That means those flower buds will sit exposed for more than half a year, through fall, winter, and early spring, entirely at the mercy of the weather. A hard freeze, a late frost, even a rough polar vortex swing in February, can kill those buds outright. That’s why so many Cape Cod and South Shore gardeners get a beautiful, leafy bush some years with no flowers at all. It’s not that the plant died. It’s that winter got to the buds before summer ever had a chance to.
This past winter’s consistent cold was just right for the plants, actually.
Now compare the Nikko Blue to the paniculata hydrangeas, like Limelight or Tardiva, which bloom on new wood. They set their flower buds fresh each spring, so a rough winter can’t touch what hasn’t grown yet. That’s a real reliability argument, not just an aesthetic one.
A brief history of the mophead
The horticultural world has always had its crazes, its obsessions with whatever flower happens to be catching everyone’s eye at the moment. Tulip mania in 17th-century Holland is the classic example, where a single rare bulb could trade for the price of a house. Humans have their own version of this going on right now, too, a trend called “looksmaxxing,” the online push to optimize every physical feature for maximum visual impact. It’s new enough that it may well fall flat on its face in a few years, the way most crazes eventually do.
But it’s tempting to think of the underlying impulse, the drive to optimize appearance above all else, as something distinctly modern and distinctly human. Hydrangeas suggest otherwise. In a way, the Nikko Blue mophead might be one of the original, and most successful, results of floriferous looksmaxxing: a centuries-long breeding project that optimized a flower cluster for pure visual payoff, at the expense of everything the flower was actually for.
The Japanese have cultivated Hydrangea macrophylla for ornamental use for centuries. Somewhere along the way, gardeners noticed that some wild plants naturally produced more of the large, showy sterile flowers than others, the ones that exist purely to catch a pollinator’s eye, rather than the small fertile flowers that actually produce pollen and nectar. They began propagating those showier plants, generation after generation, gradually breeding toward more and more sterile flowers and fewer fertile ones, bigger sepals, denser clusters, that perfect blue dome that photographs so well against a Cape Cod gray shingle-style house.
And that perfect blue isn’t even guaranteed. It goes pink if your soil isn’t acidic enough for the plant to absorb the aluminum it needs, another finicky characteristic of the mophead. All this breeding is how we ended up with the round, puffy mophead look we associate with Nikko Blue today. And like any looksmaxxing regimen, something got sacrificed along the way. It’s the plant equivalent of a heavily filtered Instagram photo: the “face” is flawless, but there’s nothing underneath doing any real work.
Hidden deep inside a Nikko Blue mophead, a few tiny fertile flowers still exist. But they’re buried in the center, crowded out, and largely useless to pollinators. The plant hasn’t lost its reproductive parts; we’ve just aesthetically buried them.
What’s blooming in my own garden right now
Which brings me to what’s flowering out back this week. The smooth hydrangea (Hydrangea arborescens), is just coming into bloom, right on schedule for early July. It’s easy to walk past this one and assume it’s some scraggly understudy to the famous “Annabelle” cultivar, but look closer and you’ll see something the mophead breeders spent decades engineering away: a flat cluster of tiny, greenish-white fertile flowers packed in the center, with just a handful of larger, four-petaled sterile florets scattered around the rim. It’s a lacecap, essentially, in its native, unimproved form.
That center mass of small flowers is where the actual work happens, pollen and nectar for whatever’s flying through the garden that day. Compare that to Annabelle, which is arborescens bred to go all in on the sterile florets until the whole head is one solid, ballooning puff of white and nothing else. Beautiful, sure. But it’s the same trade-off as the Nikko Blue mophead, just without the winter bud-kill risk, since arborescens blooms on new wood and sets its flowers fresh each spring.
The plant I have is a small thing growing on the street side of my front yard, but it’s a pretty tidy illustration of the whole argument: the wilder, less “perfected” version of a plant is often doing more for the garden than the one we bred to look perfect.
Another option? The oakleaf hydrangea
There’s another hydrangea worth knowing that provides plenty of nectar for native bees and other insects, and doubles as a host plant for moth caterpillars: the oakleaf hydrangea, Hydrangea quercifolia.
Unlike the mophead, oakleaf keeps its full cone-shaped cluster of mostly fertile flowers, with just a light scattering of sterile ones around the edges, so it’s doing real ecological work while still being ornamental. Come fall, its oak-shaped leaves turn a fantastic deep red before they drop, adding a season of interest most hydrangeas don’t offer at all.
To be clear, this isn’t an argument against mopheads. I confess I have two of them in my own garden. It’s an argument for a mix. Lacecap hydrangeas split the difference nicely: a ring of showy sterile flowers surrounding a fertile, functional center, advertising to pollinators rather than burying the thing that draws them in. I have one that blooms a soft purple this time of year. When I first saw the variety, I didn’t much care for it. I’ve come to appreciate it a lot more since I understood the drawbacks of the others.
Oakleaf hydrangeas, paniculata varieties, and climbing hydrangeas all keep more of their fertile structure intact while still being genuinely ornamental. They may not have the brilliant color the mopheads start with, but their flowers fade to soft pinks and mauves as the season goes on, and in winter, the dried, papery brown blooms of paniculata and oakleaf look wonderful standing in the landscape. That’s long after your Nikko Blue mophead has dropped its leaves and is left standing as nothing but a bunch of bare sticks.
Climbing hydrangea earns its own kind of winter interest. It does lose its leaves and flowers, but its bark peels away in cinnamon-colored strips along winding, twisting stems, a sculptural presence in the cold months and a wonderful landing spot for snow.
It’s a bit like a lawn. You don’t have to rip out every blade of grass to make room for a meadow. You can still have some lawn. You just don’t need all of it to be grass. The same goes for hydrangeas: Keep the mophead if you love it, but leave room in the garden for something that’s actually working while it’s busy looking good.
Have a gardening question for Dave? Email weather@globe.com or leave it in the comments below, and Dave will answer it in an upcoming gardening column.