Yellowing off is nitrogen deficiency; you were right in that they needed to move to potting soil.
Now, be patient. Don't overwater. Give them plenty of light. And ... be patient.
Keep in mind that there is about zero possibility of getting Chinense species in to the ground and producing, that were sprouted in
July.
Get ready for a long haul, take care of them for the next 9 months indoors and put them in the dirt next spring. (if they do go out this year, which is fine, just put them out in pots so you can bring them back in; they probably won't hit maturity before temps drop too low.)
You may get some late fall / early winter heat if things work out well.
Also don't let my remarks discourage you in ANY way. I've got some 3 year old plants still going strong (STRONG!) that I've been overwintering each year.
With perennials it doesn't really matter WHEN you start them, if you plan on caring for them year round.