Defoliating Japanese maple: Part 2
In an earlier post, we talked about pinching back Japanese maple. And now we get to the part two of that…there are three parts to this seasonal maple work, by the way, and we’ll be getting to that third part sometime in late-summer/early fall. (Actually we are onto a truism of bonsai here: if we begin monkeying around with bonsai, cutting, defoliating, etc, we are setting ourselves up for more work later in the season!)
So. Defoliating is done for a long list of reasons. But the main ones are to keep the twigs thin and delicate; to balance the tree’s energy; to get more ramification; to strengthen inner shoots by increasing light to them and removing powerful growth hormones in the tips; and for those of you who like fall display, getting smaller and better colored second-growth leaves.
In short, only defoliate strong trees. If you’ve repotted the tree, you might skip this year. If the tree is very old, you might skip if it looks tired out. If it’s sick, skip this year’s defoliation. If you’re too busy this summer, skip this year as you’ll make a mess of the tree because you have more work coming…
- In general, do not completely defoliate anything but a very young Japanese maple. They do not predictably respond like a Trident maple does to complete defoliation.
Think of defoliating as a way to rebalance a tree. Japanese maple is highly apically dominate. Your lower branches may be weak. The apex will likely have strong, thick shoots. If the lower branches are too weak, just defoliate the top. If it’s well-balanced, you can defoliate most of the tree. Leave the small leaves in the interior. It’s not a great idea to take every leaf off any tree since we lose that transpirational pull and the tree just stalls for a bit. Also, be sure you protect the tree from intense sun for about two weeks, as the interior leaves have been very well shaded and can burn when exposed.
- Basic Japanese maple defoliation is cutting off one of the pair of leaves in strong areas.
Cut the petiole, don’t pluck a Japanese maple. You can pluck Trident. When to defoliate depends on your location: generally, you wait some weeks after the leaves have hardened, perhaps June for younger trees. The exact timing does not seem critical (this is not a Black pine…) Just don’t defoliate too late, such as late summer/early fall. Late July is still ok for old Japanese maples, and may be best for a very small leaf and thin twig.
Leave two pairs of leaves in the weaker areas. This is partial defoliation.
Ok, we’ll be readdressing our maples in the summer, since strong defoliation will bring out a mass of eager shoots—and if we don’t come back to the tree soon, it will be a real mess. Bulges and scars and the whole deciduous disaster.