Q: Most of my Japanese maples are still full of dead leaves. They never exfoliated in the fall to leave bare branches. Will this affect new growth in the spring? Should I just let them be?
A: We have received several questions about Japanese maples that are still holding on to brown leaves that didn’t drop last fall. Some crapemyrtles also have held their leaves during the winter. This issue has been reported in several areas of Maryland, which suggests it is due to an environmental factor. An unusually warm autumn followed by a quick cold snap likely interfered with the trees’ normal winter preparation processes.
As the days shorten in the fall, trees go through a series of biochemical and physical changes to prepare for winter survival. In deciduous trees, this includes the development of an abscission zone of cells where the branches connect to the base of leaf stems (petioles). A layer of cells essentially seals off the branches to protect them from water loss, and then the leaves are shed from the tree. We suspect the fall cold snap interrupted this process and normal leaf abscission did not occur in some trees.
Some types of trees naturally do tend to retain dead leaves during the winter. American beeches and many oaks exhibit this trait, called leaf marcescence. This occurs most often on juvenile trees. It may be a strategy to protect buds from winter damage or to discourage deer browsing. Trees may also wait until spring to shed their leaves, thus providing a fresh source of nutrient-rich organic matter to the root zone where soils are otherwise poor. The exact reasons for leaf marcesence haven’t been determined completely.
There is nothing you need to do for your Japanese maple at this time. If your tree was otherwise healthy, new growth will emerge in the spring and the old brown leaves will drop off eventually.
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By Christa Carignan, Coordinator, Digital Horticulture Education, Home & Garden Information Center
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Some cultivars of Japanese maples hold their leaves in mild climates just because the weather does not get cool enough. Ick! They can look bad. Although foliage does not get frozen before abscising like it can in cold climates, it can get roasted late in summer or autumn, so is unable to abscise, in sort of the same manner, but because of the opposite extreme.
Tony, that is interesting and good to know. Thanks!
Oh, it is probably not important in your region. It just happens here because of our climate. I used to grow Japanese maples in the nursery, but I do not like them in the landscape in some areas here.
It happens to mine from time to time, mostly on the fine laceleaf cultivars. If you don’t like them, sometimes you can spray the hose on them with a strong stream to get most if not all of them off.
Will the old leaves finally fall off when the new one bud in spring
Yes, the old leaves will come off when the new growth emerges in the spring.
So it would be okay to remove the dead leaves by hand in January (now)? They come off easily….and are making their way into my house, one by one. Any reason I shouldn’t remove? Do the leaves protect them from snow?
Yes, it would be okay to remove the dead leaves. There is no research indicating that trees use this strategy (marcescence) as protection from snow.
I always remove the dead leaves.