ground layer

Hello all, first post here. I have a Blue Atlas Cedar that I got as cheap sickly nursery stock a year and a half ago. I got it to full health last year and now have it in a pond basket coiled into quite a lovely extreme shape with some 5mm wire (cant ground grow atm). The tree is fairly young...

I bought a pre-bonsai hinoki cypress with a thick, almost bulb at the top of the nebari. I'm considering ground layering it above this ugly area and starting over. I'm wondering when is the best time of year to actually cut into the cambian and begin the process? If I do this to the tree, I'm...