Hi,

Pot up to a 10 gal. or so for now. 20 gal. is too big. It's not ideal to put a small root system into a pot that's too big.

Some red Japanese maples hold their color into summer better than others. Some bronzing (red with green undertones) is quite normal. Morning sun afternoon shade would be ideal, though it's not written in stone. The tree will be okay on the north side...it just won't get as much sun and may no hold it's color well so expect some greening up. Also, don't feed your maple too much nitrogen as this will cause it to green up as well. Stop fertilzing by the end of the growing season and before fall in your area and give it some 0-10-10 fert. Keep the soil moist but not wet.

Hope this helps,

Layne