I'm thinking potting together with PH were the principal issues with your last grow. The roots need sufficient soil to hold water and nutrients long enough for the plant to absorb them. 1 gallon pot seems awfully small. Then again, you are keeping them short. I'm guessing that with any significant stavia strain you will need the 3 gallon at least. Do you remember what the roots looked like coming out of the 1 gallon pot?

I'm also looking at G13. I like the stavias so I'm looking at Super Silver Haze and bubblegum Kush. Light of Jah looks like a winner too.

I'll be watching your grow. Good luck!