When do you trim a tree - in winter? Should you trim one that got too dry?
This really depends on the type of tree you have, though you can go ahead and take out any dead branches. Most trees are pruned during their dormancy, which is normally in winter. However, depending on the type, it may require pruning in late winter/early spring, or even late summer to fall. As for it being too dry, you may want to rehydrate it by soaking in water for about 15 minutes or so, especially if it's in a pot.