Do you cut lilies to the ground in the fall?

No. If you live in a cold climate, only cut the stems down to eight or ten inches in the fall, so that winter-kill will only effect the top portions of the stems, and so that the remaining stems can trap snow, which will insulate the crown of the plant. In a warm climate, cut the plant down to about one third its summer size, and then in the spring trim off any part of the stem that has died.