No, I put them at whatever depth the existing leaves are, or just a few inches in the case of seedlings or dormant tubers. Then I gradually raise the level of the water over the period of a week or so until it's as high as the target location. The leaves will stretch an inch or two each day, especially the young ones, and new leaves will rise to wherever the surface is, so it doesn't take too long. This is where having them in a stock tank that I can add a bit of water to each day comes in handy.
