how far do I cut back lillies

I have been told that I should cut back lillies hard during the winter ready for new growth in the spring. If this is true, how hard should I cut them back?

Doug says that hardy waterlilies should die right back themselves. And that the stems of the lilies are pretty much mush.

So you'd simply remove the lily stems at the crown of the plant. They don't require them any more.

But unless you live in the deep South - your waterlilies are pretty much done for this year anyway and you'll get most of the debris in the spring cleanup. (or should have had it in the fall cleanup)