Just a guess before the troubleshooting form is filled out, but if you are feeding it with Miracle Grow you are likely frying out your organic soil mix. I would not bank on it being a deficiency since you are using steroid like fertilizer. My guess would be that there is some toxicity in the soil that is causing a nutrient lockout. In other words, you may have plenty of MN, but for some reason it is locked in the soil and unavailable to your plant. I think it never hurts to flush, provided your soil drains well, so until someone with a weed PhD comes around to help, I would flush the hell out of it, and quit with the miracle grow for a few rounds, let the soil balance itself back out. Good luck with it.