When and How To Prune Azaleas

I like to think of azaleas as mixed on an artist’s palette. Come mid-spring, they paint the landscape in broad strokes of brilliant color. Most seldom require pruning. That said, older shrubs can outgrow their space or become unruly. Before giving them a haircut, though, it’s key to know when and how to prune.

The Main Types of Azaleas

Azaleas are part of the Rhododendron family, a large genus of evergreen and deciduous trees and shrubs. In April and May, they produce masses of long-lasting flowers ranging from bright white to crimson. Some deciduous varieties produce unusual tones of orange and yellow. 

Evergreen azaleas are mostly native to Japan. They tend to be smallish in size, ranging in height from 4 to 6 feet.  

Deciduous azaleas, on the other hand, tend to be larger. Some can grow as tall as 15 feet. All native North American azaleas are deciduous.

Native azalea ‘Stonewall Jackson’

Although some varieties do well in full sun, most azaleas prefer high shade. Like hydrangeas, they favor slightly acid soil (a pH of 5.5 – 6). Before planting, do a soil test to determine if your soil is acidic enough. If not, add an amendment like HollyTone, making sure to follow the directions carefully.

Azaleas can be planted in early spring or fall. But in my experience, most are happiest with fall planting as they can develop their root structure over the winter. 

How To Prune Azaleas

Most azaleas seldom require pruning. But if you must – always prune them right after their flowers have faded and before next year’s buds start forming. This is typically around the beginning of July. Cutting azaleas back in late summer, fall or winter will remove next spring’s flowers. 

In my view, azaleas look best when pruned in a natural shape. Unlike rhododendrons that flower at the end of a stem, azaleas flower along the sides as well as the end. That means you don’t have to worry about pruning them back to another branch. They’ll grow a new stem right above where you cut. 

If, however, you observe damaged or dead branches, the strategy is slightly different. Cut damaged branches to just beyond the break where it joins a leaf. And cut dead branches back to their point of origin.

How To Prune Encore Azaleas

Encore Azaleas appeared in the 1990’s, the result of a cross between two Asian varieties by a Louisiana plantsman name Buddy Lee.  Unlike the usual varieties that set buds once a year, Encore Azaleas produce buds each time they produce new growth, which can be several times during the season. As a result, you can prune these azaleas two and even three times from spring to mid summer.

Do not, however, prune your Encore Azaleas after they have finished flowering in the fall. This will stimulate new growth which can be damaged by falling temperatures. As a general rule, stop your pruning two months before the frost date in your area.

How To Prune Overgrown Azaleas

Many times old shrubs outgrow their locations, or turn spindly or sparse. You can ‘heavy’ prune them in winter or very early spring before the leaves start to appear. This is called rejuvenation pruning. 

To do this all at once, cut the branches back by a third or one-half, trimming all of the branches to maintain a uniform shape.

Most experts spread heavy pruning out over several years. This prevents the shrubs from becoming eyesores during their rejuvenation. To employ this method, prune a third of the longest, oldest branches down to within 12 inches of the ground each year for three years. This will encourage the shrub to branch out and fill in over the seasons as you continue your pruning.

By the end of three years, all of the old wood will be removed and you’ll be left with a strong, healthy shrub.

 

 

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About carole funger

I'm a landscape designer and Maryland Master Gardener living in the Washington, DC area. I blog about new trends in horticulture, inspiring gardens to visit and the latest tips and ideas for how to nurture your own beautiful garden. Every garden tells a story. What's yours?