A: Put simply, magnolias just do this. It’s a perfectly natural event that happens every year. It’s harmless, but since we’ve had several questions on this single topic recently, we thought we’d explain.
Older, less useful foliage that no longer gets much sunshine, as well as stressed foliage and damaged leaves, all drop off of a magnolia this time of year. The plant is evergreen, but the foliage isn’t eternal! If you hadn’t seen it happening, two to three weeks from now, you likely wouldn’t have noticed it if the plant was thick and healthy and the yellowed leaves had dropped in normal fashion. Nothing to worry over, simply feed your plant normally, and make sure it gets enough iron and sulfur along with its normal tree and shrub fertilizer.
If your plant is thinner than normal right now, you may have missed some water last summer to early fall, and that’s the source of your plant’s current distress. Magnolias won’t warn you the way many other plants will by showing drooping leaves when they’re a bit too dry. They go pretty much straight from “I’m fine!” to “Whoops, there went some leaves falling”. Make sure your magnolia gets enough water this spring and through the summer to keep it as strong as possible. That will help your magnolia flush with enough new growth to make it look better.
Burton specializes in diagnosing and solving plant problems. If you have a question for Burton, please email him at firstname.lastname@example.org and include photos showing the problem.