RichToyBox wrote:

The lilies, depending on variety, will do fine at that depth. The main
reason that 18 inches is listed, is that is pretty much a minimum depth,
and getting in to fertilize, prune, maintain, etc, is much easier in 18
inches of water than 4 foot.

I grew lilies in 5', no problem with getting them to grow. The problem was
keeping them on the bottom. At that depth, the sheer mass of foliage
between root and leaf creates a bouyancy that either requires the roots to
be in soil, or a massive weight to hold them down. Since I like to keep
the lilies bareroot, that means fastening them to a pretty massive weight.

I did find that most lilies really need to be started in about 18" of water
and lowered about 6" at a time as the leaves reach the surface. Otherwise,
they'll grow fine but you might not get flowers until August.
--
derek