I take torn up strips of old tshirts and a bottle of ammonia with me to my grows. Then I soak the strips in the ammonia and scatter them around the perimeter of the grow trying to put them where they won't get wet. This repeals most small varmits like groundhogs and raccoons, along with bigger critters like deer and bear. If you need stronger and/or longer lasting protection, get some of the plastic, not styrofoam, take-out containers with lids. Poke small holes in the lids and fill with ammonia. Don't put them to close to the plants in case you get a heavy rain and the containers somehow overflow. Only thing I know this might attract is cats. Mothballs are effective as well.
Almost forgot, wolf urine is suppose to be very effective as well, but expensive.
