Droopy or curled up foliage on this shrub is a sure sign your plant isn't happy. Here's how to diagnose and correct the problem.

By Charlotte Germane
Updated June 15, 2020
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Rhododendrons are sturdy, generally trouble-free, evergreen shrubs beloved for their beautiful spring blooms. So it can be startling when you notice that a usually healthy plant has all its leaves curled inward. There are actually several reasons rhodies might start looking a little unhappy, depending on the season. Try going through this simple checklist to find out what’s wrong and learn how to fix the problem. Then you can go back to admiring your rhododendron's year-round beauty. Plus, here's a pro tip: Don’t forget to deadhead  (pinch off) each cluster of flowers, called a truss, at its base right after the blooms fade. If you do that each year you’ll be rewarded with lots of flowers the next spring.

Pink And Purple Rhododendron
Credit: Randall Schieber

Rhododendrons Curl Their Leaves Against Winter Wind

If a lot of cold wind blows past your rhododendron in the winter, it will curl its leaves inward so less leaf surface is exposed; the plant’s trying to keep water from evaporating out of its leaves. Here’s how to help: Whenever the temperature gets above freezing, give your rhododendron a slow and steady trickle of water until the soil feels damp 8-10 inches down.

Keep that needed moisture in the ground by adding two inches of mulch. The mulch layer should cover an area starting two inches away from the trunk and going out beyond the ends of the branches. Next fall, get your rhododendron ready for winter by makes sure it gets at least an inch of water (from rain or from you) each week.

Rolled Up Leaves in Summer Could Be a Sign of Dry Soil

Much like any other plant, if a rhododendron doesn't get enough water, it will wilt. Rhodies have fairly shallow root systems, so they need a regular supply of water. If the rain isn’t falling, you have to turn on the sprinklers or get busy with a hose. And check that you have at least two inches of mulch around your plant to help keep water in the soil. If you can, use pine bark mulch; it creates the acidic soil rhododendrons prefer.

Too Much Water Can Cause Curled Rhododendron Leaves

Rhododendrons can get root rot if they don’t have well-drained soil; putting one of these shrubs in a wet spot in the garden is always a mistake. A fungus called phytophthera takes hold if the roots are in overly damp conditions. To see if this disease is the problem, you'll need to do a little digging. Because these shrubs have shallow roots, you won’t have to dig too far to get a look at them. If the roots are mushy and black instead of firm and tan-colored, that means root rot has set in.

Treating with a fungicide won't help, but you could try to move the whole plant to higher ground or a raised bed to see if it can recover. Clay soil holds on to water, so if that’s what you have in your garden, be sure to add plenty of compost or pine bark to the new planting area. Don't plant another rhodie or azalea (they're a close relative) in the old location; the fungus will attack the new plant, even if it’s specially bred to be disease-resistant.

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