When cutting back lilies after bloom, cut back by no more than half their height in order for the bulb to continue to be fed. When the stem turns brown and dries up, then it may be cut all the way back.
I leave mine up all year so that I know where they are. That way I can watch for them so that I don't step on them while they are emerging. I have a rabbit problem and those little creatures love oriental lilies.
Maryann!
