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Help! My Azaleas have yellow leaves

Several weeks ago, a friend emailed me a question about his azaleas. They’ve been planted in the same location for many years and have always looked perfect, but this year they have lots of leaves that are turning yellow and dropping. What to do.

You know how we Virginians love our azaleas. We plant them everywhere for spring color and winter greenery. They’re the perfect companion for tulips, daffodils and boxwood. Besides, they’re a tradition! After talking to neighbors and checking my own plants, however, I found that there seems to be an epidemic of yellowing leaves this year.

A bit of research shows that we can all relax. It’s normal for azaleas to drop some of their leaves, especially those further down the stems in late fall/early winter. It’s just part of the natural process of older leaves dying and being replaced by new ones. All evergreens and semi evergreen plants do this, but the molting can seem more pronounced in some years than others.

There are several problems, however, that can cause yellowing and leaf drop. If your azaleas have leaves that are pale yellow with green venation, then the plants are probably suffering from chlorosis. The pH of the soil is too high and the plants cannot take in iron. Poor drainage can also contribute to the problem. Check the pH of the soil and treat the affected plants with ferrous sulfate or iron chelate. Azaleas prefer a soil pH of 4.5 to 6.0.

If the leaves of affected plants are silvery on top and brown on the back, then the problem is probably lace bugs. Treat the plants with an appropriate insecticide in the spring.

Azaleas are low maintenance and easy to grow. Just remember that they prefer acidic soil and are shallow rooted. It’s important to mulch them, preferably with a layer of pine needles or shredded oak leaves. Provide protection from harsh wind during the winter and don’t prune them until just after they bloom. You don’t want to destroy the next year’s blooms. Their shape is naturally open and irregular, so please resist the urge to prune them into square or rectangular shapes.

Relax, your azaleas are probably fine. Think about all the lovely blooms you’ll have in a few weeks.

Cynthia Wood is a master gardener who writes two columns for The Herald. Her email address is Cynthia.crewe23930@gmail.com.