Another vote for a golden rod, however in a high humidity enviornment like a coastal ( particularly saltwater coastal ) or lakefront home you may want to reconsider placing it in the garage. get a humidity indicator and check it on a regular basis.

A final suggestion...hide it in the garage, behind an old refrigerator box, or something similar. Thieves won't spend alot of time trying to steal something that they don't readily know is there...