Hydrangeas are like dogs, many and varied
By Ted Manzer
Saturday, August 31, 2019
Asking if you like hydrangeas is like asking if you like dogs. There are so many types. There are bigleaf hydrangeas, mountain hydrangeas, smooth hydrangeas, oakleaf hydrangeas, panicle hydrangeas, and climbing hydrangeas, just to name a few.
Hardiness and adaptation vary somewhat among types. Smooth, panicle, and climbing hydrangeas are most adapted to cooler places. These types bloom on the current season’s growth. They grow here but really thrive further north. I remember growing up and picking white flowerheads as big as volleyballs from the smooth hydrangeas in my grandparents’ yard in Augusta, Maine.
Panicle (often called Pee Gee) and climbing hydrangeas must be planted where they aren’t in the mid-day sun more than a short time in our climate. Further north it doesn’t matter as much.
Panicle types have elongated clusters of blooms. Oakleaf can vary in shape and often have a pink blush. Climbing hydrangea flower clusters tend to be flat. They also are more shade-loving than most hydrangeas.
The most common types are the bigleaf hydrangeas, often called French hydrangeas. They flower on both this and last year’s growth. These are the blue and pink types. They flower blue in acid soils and pink in neutral ones. Sometimes they bloom purple or even red.
If flower clusters are uniform, we call them mophead types. Lacecap types have broad sterile flowers around the outside of the cluster and tighter fertile ones toward the center.
Mountain hydrangeas are often grouped with the bigleaf types and also flower largely on the previous season’s growth. That’s one reason they are somewhat less adaptable further north. They are also a pink or blue type but are normally much shorter than bigleaf varieties. Pretty much all other hydrangea types have white flowers.
All hydrangeas benefit from deadheading. They also thrive in soils with high organic matter. On sandy sites it’s often necessary to incorporate organic matter or mulch heavily. These plants are not especially drought tolerant and will usually wilt on hot afternoons.
Also, while some folks like pink hydrangeas, adjusting the pH too high can be detrimental to their health. Even slightly acid soils will yield pink hydrangeas. Soil pH should be 5.5 or slightly less for blue blooms. Purple flowers often result from soil pH levels around six.
As well as being a great colorful landscape shrub, hydrangeas are great in cut-flower arrangements, both fresh and dried. Sometimes there is no substitute for a huge flower cluster and hydrangeas fit that bill.
Another tribute to their versatility is their use as medicinal plants. Smooth hydrangea is the major species used, and the most common maladies addressed are urinary tract and prostate problems. Teas and other preparations act as a diuretic and cause a loss of water.
Those taking lithium should refrain from using hydrangea for these problems. Roots and rhizomes are the part of the plants most commonly used medicinally.
One thing I like most about hydrangeas in the landscape is that they don’t usually require much pruning, and they can’t really be hurt by pruning. I like forgiving plants with multiple uses.
Ted Manzer teaches agriculture at Northeastern High School.