Anybody from CO with J maples?

JR_Roosa

Hi TT. I know I've posted several times on your maple and soil threads, and I hope you're not sick of me yet. Did the other one come back?

I only have basic advice to offer, but maybe it will be a good start.

Anyway, to amplify what dpqmonkey wrote, the japanese maples for lanscape are a little marginal because we're dry year round, because the winters have cold snaps, and because we don't get much snow cover to protect roots. One spot (sheltered from heat and sun) is the best spot for the summer, and another (sun for a little warmth and shelter from drying wind) is good to overwinter. Fortunately you can work around a lot of that in a pot since you can move the tree to fit the conditions.

For the summer, water and sun are the issue, and morning sun, afternoon shade worked well for me last year. Regular water is a must since the leaves lose a lot more moisture than the needles on my other trees. Because our water is really hard (at least where we are in Centennial it is), I made sure to use miracid on the tree to protect it from the clacium in the water. Without the acid fertilizer, I would get little dead wedges on the leaves, supposedly from calcium precipitate in the vascular system of the leaf. You might want to verify elsewhere that miracid is a good idea. When it's cool, I gave the tree more sun to keep it from getting leggy (and that keeps the red leaves more red). When it got really hot, I'd move it to an even more sheltered place in the yard. I had one bad week of too hot and not enough water, and I lost most of the leaves on the tree. It came back a little, but the early winter snow/freeze finished it off when I foolishly let the root ball freeze.

Overwintering went well in previous years, though last year I waited a bit too long. I bury my pots in a 2ft x 4 ft x 1 ft high wooden box filled with shredded bark next to a south-facing wall of the house with almost all-day sun and a brick wall to hold some heat through the night. I made sure there were a few inches of bark over the pot but kept some air around the trunk. I kept the bark just a little moist through the winter, which only needed watering every two or three weeks, but I kept an eye on it none the less. I think the idea is that the water in the mulch freezes first, slowing the temperature drop inside the box, and when it warms up, the water in the mulch thaws first, slowing the climb in temperature. I suppose the stability is the important part to keep the trees happy, but the relatively high humidity probably helps too. When I pulled them all out this spring, the pots were still frosty despite several weeks of moderately warm weather. Once they are out and warmed up, they come indoors any time the temperature goes below freezing at night in the spring, since I understand that they quickly lose their cold tolerance when they start growing.

All of my trees go in the box for the winter (except one that I winter inside) and they all did very well. I assume my maple was dead before this winter hit, since it never really lost its leaves properly, they just dried up on the tree. Very sad.

I've also heard that a good deep window well with the mulch cover on the pot/roots works well, but I've never tried it. It's too easy to forget the tree is there and to let it dry out, especially since it seems I can't be trusted to keep it watered in the summer. Other places suggested that the garage would work, but I'm hesitant since ours gets pretty warm from sun on the doors. That might not be the best for keeping the trees in dormancy, and leafing out in the dark in January can only be bad news.

I would get a little die-back on the tips of the newest growth (especially the long, leggy growth from late in the season that I didn't bother to prune) on my old maple after winter, but never too serious. The major branches and trunk were always fine, and it would replace the dead growth quickly with new in the spring.

That should be a good start, but I don't have years of experience. You should go to one of the Rocky Mountain Bonsai Club meetings at the botanic gardens. They'd probably have some more subtle advice. I keep meaning to go, but something always seems to come up.

Good luck.

-J.