Hydrageas illuminate summer shade gardens

Garden fads come and go. Fashion has penetrated even the sanctity of the garden bed. Heucheras are in; hollyhocks are out. Tropicalismo is trendy; privet is passé. But no matter what botanical marvel is in vogue, when it comes to summer color, the hydrangea is always in style.

Hydrangea macrophylla is an old-fashioned garden favorite that does well in most climates, but absolutely thrives in the Pacific Northwest. Often called mophead or big leaf hydrangea, its botanical name translates from Greek to “water vessel,” and it lives up to its name. It enjoys our wet winters and abundance of overcast skies. It relies on regular watering in summertime, and lives happily ever after in shady places, protected from hot midday and afternoon sun. A well-behaved and undemanding deciduous shrub, it is rarely bothered by insects or disease.

Plant it in humus-y soil and treat it to an occasional feeding of rhododendron-type fertilizer, and it will reward you with masses of bulbous blossoms in sunset colors. The flowers can be dried in early fall for beautiful, everlasting arrangements and wreaths.

Hydrangea macrophylla is easy to propagate from cuttings or ground layering. A Web site that has uncomplicated directions for both methods is Click on “Propagation.”

The mophead can grow to a mound of six or more feet. If you want to keep it smaller, prune it soon after flowering, as it blooms on the previous year’s wood. It’s best to prune it by just one-third per year. If you prune it down to the ground all at once, you won’t have any flowers the following year. In the spring, cut out any dead wood and remove a few of the thicker branches to encourage new growth.

The mophead hydrangea is the botanical equivalent of litmus paper. Most will produce heavenly blue blooms in our acidic northwest soil. To increase the intensity of the blue, work a handful or two of Epsom salts into the soil in late winter or early spring. If you add a few cupfuls of garden lime, the blossoms will take on a pink cast. You can also purchase naturally pink cultivars in shades ranging from baby-girl pastel to glowing-ember hot.

I’ve long admired the hydrangeas that grace the front of Oak Harbor’s City Hall. For more than 25 years, they’ve produced huge, healthy blooms in eye-popping shades of purple and pink. The man responsible for their care is Oak Harbor Parks Manager Hank Nydam. I asked him how he does it, and was surprised to learn his “secret.”

“We trim the shrubs back in late fall, and in January, feed them with stump remover,” he says. Stump remover is potassium nitrate, and in small amounts, can be used as fertilizer. Follow directions on the box, and your hydrangeas may rival those on the hallowed grounds of city hall!

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