I wonder this myself. I had a large plastic tub (probably 30 inches tall and across) and I cracked the bottom of it w my shovel. then I filled it with rocks and then soil and planted a clem vine in it. It is sitting directly on the ground with nothing lifting it up off the soil, my clem has been looking kind of ratty lately and I blamed on the 100F temps. But we have had TONS of rain this past couple months and now am wondering if the pot isn't draining as it should be? I guess in the back of my mind, I am thinking I should have put it up on some 2x4s or something to lift it up and allow it to drain. Afraid having it sit right on the soil kind of sealed it so that it won't drain. Now I don't know what to do because it is heavy and there are plants around it now and the vine has been in it for a year now. It did bloom really beautifully this past spring-before all the rain though. I think if you are starting out-haven't got them filled and planted already, I'd probably raise them up a tad, I think it surely would help them to drain better. Wish I had did mine.
