snip---
Just to add a comment to the above (which I completely agree with). If
you
live in an area with severe winters, you may want to put the hardy lillies
in a deep part of the pond over the winter, and then bring them up again
to
shallower water in spring. This is difficult to do if they are not in
tubs.
Some hardy lillies like to grow in shallower water over the summer than
other lillies. Our Attraction thrives in deep water, the others do not.

Thanks, but I'm in zone 10.75 (meaning, not quite 11, but close). Isn't
frost addressed by washing it off with the garden hose? ; )

Still, I think I'll put them in containers, thanks for the advice.