Acer palmatum sapling

I have an Acer palmatum that takes a lot of work to keep under control. Foolishly, about three years ago, I decided to see what would happen if I grew one from seed.
It grew. It's a nice shaped plant and it needs repotting. I'll do that but then what? They grow huge if you plant them out and if not, eventually they need watering about 3 times a day.
Be careful what you nurture. The white elephant might bite you on the bum.