i really don't know the answer but i'll give you a bump as this post is slipping away. my guess is that it might work that way. we dead head many of our other flowers because it takes away from the plants energy to keep them and produce seeds from them. why not WL's?
i also wanted to say thanks for the fantastic lilies you sent me. put in the pond yesterday and mayla already opened up a a bloom today!! just a little tulip shaped one, but a beauty for me to behold anyway!! pics will be forthcoming but i guess you;ll have to see them when you get back. have a great time 'slothing'!!