Web Master:
Hey Jake you probably bought good plants but your treatment of them has not been perfect.
Always plant them in separate pots - that's probably the #1 reason the parsley is suffering.
All these three plants are nitrogen hungry and the plant with the strongest roots probably took precedence over the others - it seems your parsely has been the victim.
Secondly ensure your herbs are well drained - this is more important than watering, believe it or not. They will take short periods of dry but they will never do well with wet feet, it makes their fine roots rot and these are the main uptake for water. .You really shouldn't need to add more water everyday, especially with a self-watering pot - once every 5-6 days should be fine
Self watering pots are designed for lazy gardeners and in most cases are dangerous in the wrong hands.
I hope this has helped.