I would say that if you keep that wet, you'll end up with a very happy ball of moss and a very dead maple tree. I won't say what else I think right now.

Aw, go on. Let me have it.

Get rid of the moss ball, get it into the ground or a large pot and by all means - get that tree outside!

Right. I took apart the moss ball. Moss on top, peat on the outside, stones and very light brown mud inside (mud, of course, because the ball has been kept constantly moist). Moved it into a (small) pot of rich, yet well draining soil, have it in a shady location outside (quite shaded, doesn't get any direct sun during the day -- shouldn't be shocked tooooo badly by the sudden outsideyness). Will buy a larger pot for it Wednesday (the first day I have the time to, unfortunately -- had time today, but didn't ask about it until the shops had closed -_-).

That soil should not be "rich", but sandy gritty stuff full of gravelly bits that drains right away. And let it get a little more light, won't kill it unless you're in Phoenix.

I'd leave it in the shade for at least a week.
Gradually introduce it to brighter light. The roots aren't back "online" yet, so it
won't be taking up moisture or photosynthesizing at full capacity...

Larke's right about the soil mix. A gritty, free-draining mix will not hold its shape when wet.
If you take a wet handful, it should simply fall apart. In the long run, a gritty mix will
make subsequent re-pottings a breeze.

Josh

It's only in that because it's the only thing I had handy. It's a stop-gap. I'll whip up a proper, grittier mix on Wednesday.

Right, it's Wednesday, and I popped out to get components of a grittier mix. During my lunch hour, I did a Google search for 'maple soil container' and found a post (this one) by Al (he of the Gritty Mix) suggesting a mix for Japanese maples. I went with that, or close to it, any way.

1 part granite grit
1 part Turface (not exactly turface, but the same sort of deal)
1 part pine bark (fresh)
0.3 parts "red loam", medium grain (roughly the same size as the crushed granite and the turface), as suggested by the master gardener at the center (I figured I'd take his word for it, since I'm in Japan, and the guy probably knows his native trees).

I suppose we shall see how it does in the next little while. I've still got it in shade, since being stressed by the moss plus having its roots disturbed, at this time of year, twice in a week doesn't make for a happy tree, I reckon. I'll move it to a place where it gets more sun in a week or so, depending how things go.

I know y'all probably get well annoyed with questions like this, but I appreciate the help.

Why should we get annoyed? Definitely not, that's what the forum's for, and at least you're not asking absurd questions like some people :-). And that mix sounds perfect!

I just noticed this thread. The technique of planting in moss covered balls instead of pots is called 'kokedama'. The soil is a muck soil, commonly used for rock plantings and building dams for slab plantings.

Al