Please tell me if I am making a mistake. I built a planter and sub-divided it into three "cubicles" approximately 3' square by 3' deep each. In one cubicle I transplanted a Japanese Maple and in the other two I planted some bamboo that I had growing in pots. The two bamboo species that I planted are Narihira in one "cubicle" and Black Bamboo in the other. I read somewhere that bamboo can go down up to 30" so I built the planters 36" deep. However, after seeing the root systems that were in the pots I am a little concerned because I built the planter directly over my electrical and water utility lines coming into the house. There is about 4' between the top of the dirt in the planters and the utility lines which I figured would be plenty but I surely don't want the roots from the bamboo plants getting tangled up in the utility lines. The planters are open on the bottom so there is nothing to stop roots from travelling down to the utilty lines. (The sides of the planters are wood with two layers of 6-mil plastic around the sides so I am not concerned with roots getting out the sides) It's not too late to plant the bamboo somewhere else if I am making a mistake in doing this but I don't want to have to try to dig them out a year or two from now. What do you guys think, will my planter contain my bamboo or should I re-think this? Also, I know this is the bamboo forum but does anyone know if the planter will be adequate for the Japanese Maple as well? Thanks for any advice here.

Matt