miracle grow tends to run a little "hot", or powerful on the ferts. it's often good to cut the soil with something, whether it be perlite or soil or whatever that doesn't have nutes in it.
you can try to leach the nutes out, or pour large amounts of pH'd water through your pots to get the built up nutes out.
you could also transplant into a better quality soil. that's what i would do. then get yourself some nutes to use so YOU can control the feeding of your lady.
-shake