Answer: Some Rhododendrons are more prone to bark splitting than others. Usually winter sunscald causes this, but sometimes mulch that is too close to the trunk will hold too much moisture against it and cause softening which can then turn to splitting. Rake the mulch away from the trunk of your plant and if it is exposed to winter sunshine, set a decorative pot or large rock in front of the plant to block winter sun. A healthy rhodie will compartmentalize the split bark and the interior of the stem will be just fine - the splitting will not look nice, but it shouldn't kill your plants. Good luck with your garden!
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