To keep squirrels from eating your plants sprinkle your plants with cayenne pepper. The cayenne pepper doesn't hurt the plant and the squirrels won't come near it.
Julie Notes: I heard this was a good way to keep cats out of the garden, so that's what I tried this for . . . I'm not sure it worked or not, but it's really hard to put enough cayenne on you garden unless you can buy it in bulk. Also you have to re-apply it every time it rains. Maybe it works better on squirrels, but we don't have squirrels where I live. I guess with them you only need it directly over/around you plants, but for the cats you need to cover pretty much every inch of dirt because they just want to use it as a litter box.