Heavenly Hydrangeas for Your Home

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Drop me on any back road in the foothills or mountains of North Carolina and I could identify the region by the wonderfully varied shades of blue that characterize the Hydrangea macrophylla. These timeless shrubs are found in almost every landscape here in western NC and one amazing aspect of their presence is the variation of blues that can change from deep purple to Carolina blue and occasionally pink, many times in the same planting. Sometimes called mopheads, these hydrangeas thrive in morning sun and afternoon shade. The color variation from blue to pink is determined by the pH of the soil with blues needing a pH of 5.2 to 5.5 and pink flowers requiring 6.0 to 6.2.

Folks are perpetually confused about when to prune their blue beauties and incorrect pruning can mean no flowers the next year. Different types of hydrangeas are pruned at different times but the blue and pink hydrangeas (Hydrangea macrophylla) along with the oakleaf hydrangea (Hydrangea quercifolia) are pruned in the summer after they finish flowering but before August. The flowers on these varieties bloom on one-year-old wood and the flower buds are produced in August, September and October for the next year’s blooms.

The remaining types of hydrangeas, which include snowball (Hydrangea arborescens) and PeeGee (Hydrangea paniculata) hydrangeas produce flowers on new wood. The only time they cannot be pruned is when they are getting ready to bloom. Since the snowball flowers in the spring, it can be pruned in the fall, winter or summer. The PeeGee hydrangea blooms in the summer so it should be pruned in the fall, winter or spring.

How can the gardener tell which of these hydrangeas is growing in his landscape? The color of the flowers is a great way to identify the type of hydrangea you have. Hydrangea arborescens has huge white flowers that open up green and gradually turn white, fading again to green as the blooms age. Hydrangea paniculatas open up white and fade to pink. The shape of the flower can be round or cone shaped. Remember that these types bloom on the new wood.

Hydrangea macrophyllas always bloom pink, purple or blue and are that color when they open. The Hydrangea quercifolia opens white and fades to pink. The flowers are cone shaped and quite large. Another way to identify this hydrangea is to note that the leaves look similar to oak leaves. These hydrangeas both bloom on one-year-old wood.

If you have problems identifying or pruning your hydrangeas, contact your local Extension agent for some advice. They will be sure to get you on the path to gorgeous blooms every year.