I have a lemon tree that I've recently got from a friend. I keep the tree in a window indoors. It was started in December last winter, so it is about 9 months old now. Right now it is about a feet tall, and I need to prune its branches and leaves.
First, when is the best time for pruning an indoor lemon tree bonsai? I read here that timing is critical when pruning the roots and that you should only do so when the plant is dormant and flowering / fruiting is finished (I don't know if this is specific for lemon bonsai or if it is like this for all bonsai). But how do I know when my lemon tree is dormant? Will it even go dormant when standing inside, since the temperature is almost the same all year around? I also think that the tree is very far from bearing any fruit, and I either don't know it it will flower any time soon.
But that's just the roots, those are basically the least of my concerns, at least for now. I need to prune the branches of the tree. Is it okay if I trim it quite hard right now? The top of the trunk has been pruned at some point (I don't know when) and is currently 24 cm tall, but since the time of the pruning, one of the side branches has grown very large, and now reaches 36 cm from the ground! This branch is also somewhat thicker than what the trunk is just above the branching point, and the trunk gets significantly thinner above that point. Even though it is just a branch sticking out at the side of the trunk, I looks like it contains at least 50 % of the tree's total mass above the ground, which looks a bit wired. Since it is that large, will the tree survive if I just cut off the entire branch, and if so, can I do it at this time of the year? I want to encourage the tree as soon as possible to put more new growth into the trunk and into the branches that I want to keep, and not any more growth into this branch.
Also, I want to make the tree get more and smaller leaves, so it looks more like a real bonsai. How should you leaf prune a lemon bonsai? Can you just cut of all the leaves off at once, as you can with some other bonsai, at least with some deciduous trees, or is this different because it is an evergreen tree? I also need to know if I can leaf prune it already or if I have to wait until it has grown stronger.
Thanks in advance to anyone who can answer these questions!