From looking at your pics I see you are using green pots. If its hot where you are and those pots are getting direct sunlight, they are heating up the soil and cooking your roots. That's what I had happen to me so I have a little experience with this one.
As far as Miracle grow goes... after a month or two the nutrient levels in the soil are depleted quite a bit (not completely but still they're lower) so I would go with the heat thing.

Just keep an eye on your babies and see how they look. They'll tell you if something is bothering them by the leaf structure and color. If they're green and happy leave it alone, nature knows better than we do Also, I know how tempting it is to wanna feed the crap outta those babies, but you should just be patient and watch your plants carefully... they'll let you know if they need food.

I hope this helps my friend! Good luck and a great harvest to you!!!

Zion