i could be wrong, but it looks like from the image that there are multiple plants in each 2gallon pot. if that's the case, at that size, I would imagine they're killing each other, in that the plants will compete for water, nutrients, etc. Also, I agree with Bigrintxas, in that its better to water a lot but less frequent as opposed to a little and more frequent. The roots won't grow properly. You want roots to grow more vertically, and you need enough water to penetrate deep enough for this to happen.