OK, really dumb question, but are you referring to squirrels or actual rats? We have roof rats (aka tree rats) out here in the tile roofs, and I used to see them in our holly tree until I had the evil thing cut down (when those leaves get dry, the spines are like needles.) I know they weren't squirrels, since we have plenty of them for comparison as well, and I saw their little skinny ratty bald tails. Yeeeccch.
But I digress....I coated my tulip planters in cayenne this spring. Had to do it pretty frequently, but it seemed to work. However, that was to keep them from digging vs. eating what was actually there. I've tried the hot pepper wax sprays before on tomatoes, and they unfortunately didn't seem to do much. One of my friends tried the coyote pee stuff, but I'm not so sure about having that on stuff you're going to eat. And apparently if you have dogs, the coyote pee will make them nuts.
