When to Take Off Japanese Maple Leaves in the Fall?
This is a tangly question…there’s what’s best for the tree, and there’s what we might want to do because fall leaves are rather nice looking.
For Japanese Maple, the fall color is often the most eye-catching thing in the yard. We want to see it for a while. But, if we wait until the leaves dry and fall off, we won’t be able to do any fall canopy pruning. The reason is that the tree will bleed for a long time if we cut after the leaves have fallen off naturally. For most Japanese Maples the window of time after leaf fall that you can safely prune is less than a week, much less than the 10 days often reported.
There’s two solutions to this…take the leaves off when at the height of color or just after, and do a careful fall shoot shortening immediately, or wait until spring to do this pruning. The first option shortens the time you get to see your tree in full color, the second will offer a possibly rougher looking tree during the winter silhouette time. Maybe the solution is ask yourself if you’re a color person or a shape person…either way, it’s a decision partly based on the tree’s needs, partly based on bonsai technique, and partly on personal preference. (And if you like to keep a tidy yard, pulling leaves off a tad early will greatly reduce picking up leaves off the ground).
One final point. If leaves are taken off while they are still green the tree loses resources. In the fall the chlorophyll is broken down to salvage amino acids and nitrogen, which is then brought back into the tree before leaf abscission. This helps strengthen the tree though the winter. (Anyone still convinced of the 0-10-10 fertilizer regimen in the fall for temperate trees should give this a long think…)