As Jim said, hard to tell without a better pic - though this one's not bad. Any possibility of a macro against a white background? Close-up of the face and one of the body? I agree it's always best to know what's eating your crop. Hard to fight some pests if you don't know just what they are. And some caterpillars are awesome enough I would raise them just so I could release the butterfly. My money is on Spodoptera Ornithogalli: http://bugguide.net/node/view/142846 Moth, nothing neat this time. Definitely get rid of it and start looking hard for more - there probably are. Maybe buy some insidious flower bugs or similar to destroy any siblings. If I'm right about the id, I find the kin to this caterpillar in my area make good food for resident orb weavers. Just toss 'em in a web. Spiders are my specialty though, not Lepidoptera, so I could be wrong. Also, these moths pupate in soil and that one seems close to the soil. Seriously consider replanting and getting rid of as much of that soil in the pots now as you can. Why allow more to breed and lay more eggs on your plants. Prevention starts there - and possibly with a sponge of Sc parasitic nematodes for your potted plants. =)

The range of the Imperial Moth appears to be largely east of the Mississippi so if you are it may well be. The larva feed on a large variety of trees and shrubs but apparently not to the point of being a pest. Here is a link that might be useful: Imperial Moths

Quite similar to Noctua pronuba, the Lesser Yellow Underwing moth. These are very widespread and common. I had to lessen a related (N. comes) population a few years ago by gathering them at night off of rhubarb, carrot, and other foliage. These caterpillars vary widely in appearance, but the first two dark triangles near the rear are distinctive for the species, your specimen may or may not be the last instar.

It's some type of Tussock moth. Don't touch the caterpillar, many of them sting :(