half bare repot

Apologize if this has been answered elsewhere... I've searched for some time and can't find! What is the technique when watering a tree in 1/2 field (or nursery) soil and 1/2 bonsai soil? Do you -water the field soil half at different intervals than the bonsai soil i.e. on an as needed basis...

I bought this Atlas Cedar a couple of months ago. It looked like this: So I though it might look good like a semicascade, like one I love So I bent it, thinking it should grow some 10 years: So I half bare rooted it (as I don't know if I will be able to get another atlas cedar) and...