Posting this Q&A that began over in our email, in hope some of you have some additional substitute-tree suggestions!
Our Japanese maple has gotten pretty funky. Last winter killed part of it so I cut out all the dead stuff.
That on top of pruning over the years has left it with a lot of tiny branches on the ends, not much in the middle.
Plus the shape is weird now. I’m trying to decide what to do with it. Maybe it will look better when the leaves arrive?
- L. D. -
We're going to yank out some Japanese maples this year. Sorry to do it because they are, like yours, survivors of the worst winters ever. But we've watched them a year now and think they only survived, they didn't come through with enough good wood to be vigorous again any time soon.
They didn't flush out well last spring. Then they lost more wood in midsummer, probably as a result of accumulated cambium damage to the main trunk. Grew okay in the cool weather but once the crunch came in summer and the foliage really needed lots of water to replace what was evaporating in the heat, the root system wasn't up to it. The loss of roots was part of the winter damage, just not see-able.
With fewer leaves (result of winter branch loss), the tree had less energy. The leaves have to make all the sugar the whole tree needs. They make it and turn it to starch to send it to the wood and the roots. Fewer leaves = less starch = a starving tree. Given the damage to trunk and main limbs (didn't die but had their cambium killed on the most exposed surfaces*) the pathways for starch to move down to the roots were greatly reduced. The cambium, the ONLY route the starch can take, is like a nylon stocking stretched over the wood, under the bark. Damaged, it becomes a stocking full of runs and holes that are dead ends for starch.
(Often the space right above some cambium damage --
blue arrow - is where a lot of tiny new branches start -
green arrow; it's the tree using that starch that's stuck there.)
*(Sorry for being lengthy. Better explanation of cambium damage and protecting against it, in What's Coming Up 68.)
So there's less starch overall, plus some of what the leaves did make can't reach the roots. Now some roots starve, and die. The next summer the tree may lose even MORE leaf and twig to summer heat!
These trees are not going to be able to gain ground, or not very quickly because they're in this loss-feedback loop. Perhaps they'll end up increasing leaf surface by 10% by the end of this year, and that will mean more roots and a better summer survival the next year,. That next year they may gain another 20% in foliage. Maybe in 3 or 4 years they might regain normal growth -- which would be to increase their leaf surface by at least 50% each year. That's enough to be able to support existing and new wood and roots, plus recoup quickly from normal losses.
Since most of these trees are in prime places -- spotlight plants, focal point plants -- we really can't wait that long. Shoot, a tree may just start gaining and then get walloped in another bad winter. Another winter hit is especially likely if the tree's in one of those spots exposed to west and south sun in late fall/early winter.
So we're working on non-Japanese maple replacement strategies. Probably post an article about it. Trost dwarf birch for the ferny look. Tiger Eye sumac for the ferny look and fall color. Tina crabapple for the cute-little umbrella role. Pygmy beech for the purple leaves. Nothing will quite fill the Japanese maple role but we'll do what we can.
Any additional replacement ideas out there?
Or we'll put in a a new maple and cover it every winter from now on. Ugh.