Michael J. McGroarty
Perry, Ohio Copyright 2011
Japanese maples are really a lot hardier and easier to grow than most people give them credit for. I often get asked; “Is my Japanese maple dying?’ and usually when somebody asks me that, their tree is more than likely in trouble. They’ve noticed that something is changing with their tree.
Usually leaves turning brown around the edges, brown spots on the leaves, or maybe leaves falling from the tree during the growing season. Brown spots on the leaves during the growing season can be caused from a number of different things, and for the most part none them are of serious concern. Usually brown spots appear because the leaves got wet when the sun was out and that can cause a small burn on a leaf with a droplet of water on the leaf.
Brown edges can be a sign of a tree that de-hydrated. But often times, late in the summer, especially with the dissectum varieties, the edges of the leaves turn brown just from the extreme heat and the wind blowing across the leaves. It’s a lot like holding a blow dryer to the leaves. Does this mean the roots are dry and need more water? That depends on how much rain you’ve had in your area prior to this happening. It is my experience that this drying of the edges of the leaves is just something that happens and seems to happen to most of my dissectum Japanese maples every year starting around late July. It’s certainly not something I get concerned about.
Now if all of the leaves on your Japanese maple are turning brown and falling off, you have a serious problem. If your tree has only been planted for a short time there are four things that I’d look for immediately.
1. Have you been watering the tree as needed. Trees that have only been planted a few weeks or even a few months should be watered once or twice weekly, but it’s important to check to see how moist the roots are before you water. The soil should be moist and cool to the touch, not powdery dry. But the soil should not stay soaking wet all the time.
2. How wet are the roots and or the soil around the roots? Japanese maples do not like wet feet. They don’t like standing water around their roots for very long at all. When you water the water that you apply should drain away within an hour or so and not linger around the root zone of your plant. If you have heavy, wet, clay soil that does not drain well you should plant your tree with the entire root ball buried in the ground. The root ball needs to be covered with soil, but you should raise the bed so at least half of the root ball is above the grade of your bed. This is only true if you have clay soil that does not drain well.
3. Is your tree planted too deep? Even if you have really good soil that drains well, the top of the root ball should be at least one inch above grade. Make sure the root ball is covered with soil so you actually have a slight mound over the root ball so excess amounts of water are shed away from the tree. There should not be more than one inch of soil up on the stem of the tree. If you have the tree planted too deep and there is three or four inches of soil on the stem of the tree it is planted too deeply and should be raised immediately.
4. How much have you fertilized your tree? Japanese maples don’t like and cannot use a great deal of nitrogen fertilizer. It’s much safer to mix rotted cow manure (bagged) into the hole as you plant your tree and not fertilize at all. If you really feel the need to fertilize a Japanese maple, use something organic, something low in nitrogen.
Is it possible that your Japanese maple is suffering from some dreaded disease and dying? Probably not, but just in case visit this page: Japanese Maple Diseases.