you might have to leave it on throughout next summer so the heat kills it. covering it for the winter might just be doing it a favor.

Ceba

Liriope is very hardy stuff. Are you sure someone might not like to have it? If I lived near you, I would come and get it to plant at my school, which has many bare spots, that would love some cover.

I give away to anyone who wants it, also sell part of it thru the local seed/feed. But I have LOTS.
Say, at the risk of being indelicate, why not strip off the black plastic and just keep dousing the pile all winter with family's uric acid? Would it suffiently burn the liriope? Would it chase off/kill my beneficial critters?
(I must say, this is not something I can ask my friends, even the ones who do garden.)