I went away for 3 weeks, and most of my trees are alive. Ecept some of my bonsai and a couple of others. Well, I can't blame my sons... Here's one that I can save : a seedling, slightly weeping, in a corner that they didn't water enough apparently. A couple of days after I came home, I noticed that some buds were green. three days later, after watering, I saw some new leaves. 1/ not so good, but some green on the buds : OK, let's trim the brown branches. I could have done more actually, and choose another container. I always put some lava rock at the bottom, not much, half an inch or so. Substrate : 25% pozzolane (3-5 mm) and 75% "potting soIl" from a garden center, usually with a little fertilizer added. The pozzolan has sharp edges, helps yhe roots to divide. Since I put 1,2 cm pozzolane at the bottom, I can trim the longer roots. 7.5 cm, 3 inches at the bottom, 2 cm (less than 1 inch) on the sides. Here it is. More pics in a couple of weeks.
Great info. I will examine my tree more closely this coming weekend and look for new buds and dead branches. I am a little nervous about disturbing the root ball after such a stressful event.
Nine days later : A couple of hours of sun in the morning. I will probably trim it a bit more after leaf fall. Here's another one that I thought was dead, but it looks like it will survive. I think it's Acer elegantulum or a similar species.