Tiffany - Below is a link to the wicks that I use. I like them because they are easy to cut to any desired length. I have never had a problems with them and I have some in place for 10+ years. I can't say they are superior to other wicks. You may want to experiment a bit.
http://www.silksareforever.com...
I apologize for that unwieldy link. If it doesn't work, just google "plant water wicks" and that will take you to the site.
The wicks should work equally well with either terra cotta or plastic as it is the potting soil that determines the capillary action. I'm not sure that very sandy potting mixes wick very well. Of course, terra cotta pots will always breathe more and generally require more more water, all other factors being equal.
