With holes leading to tubs. The sealed wood could last quite a while, but with dirt and water sitting on it 24/7, not indefinitley. I am going to attempt a planter box for my FR this summer, with no drainage. Its all going to depend on the RH were you live, how much you water, and the volume of substrate used. Its possible to have the planter box in the bottom, without it becoming hypersaturated. This was my concern as well. I think that in my situation, it wont be a problem. Running 3+ nozzles on a small amount of soil, could be though. You will just have to decide for yourself.