Good points, but see, these laurels are suckers but they do drop a lot of leaves, which turn in nice black dirt. I dug about 2 feet down and screened my soil from all the roots and saw down the fattest ones I saw in that 2 feet are. but I am sure they go deeper than that. I dug last year, but the weather and work caught up with me and I could not finish up the project. I put some plywood as a barrier, well, that will rot and will feed the monster. I like the garbage can idea, but I think they will still send up roots up the garbage can. the top one foot of soil near them is very beautiful, 20 plus years of undisturbed rotten fallen leaves, but now it is time to make them produce food.
I wish they were palm trees.