So I've got a single meyer lemon in about a 4-5 gallon plastic pot, and I'm trying to come up with a minimal maintenance idea to keep it sufficiently warm this winter. I'm in N. Mississippi, so it won't be too cold, but we'll get some cold days.

I thought about moving it in and out of the garage, but it just takes one night to forget about it and I've lost my lemon. I'd rather have some sort of heating device I could set on a timer to keep the roots warm (well, 40 F or so) on cold nights. Any ideas?

Can't bring it inside - my lunatic cat will eat it.