okay im retarded, i musta forgot i was on a computer... so google supplied me with this info (via the miracle grow site faq):
"How long will Miracle-Gro Organic Choice products feed my plants?
The natural plant food used in our Miracle-Gro Organic Choice products contains nutrients that are quickly available for fast greening and growth. The remaining nutrients release slowly and consistently for up to three months to sustain and keep the plant growing."
so basically, you will not want to add stuff in general, but esp. not w/out testing the soils npk throughout its life. once you find an opportunity in a grow stage to introduce more of one of the three, use a very simple organic tea or chem to supplement that one aspect (as slightly as possible). thats the problem with that time release shit, what a bummer.
aka plants need diff. npk balances @ diff. times. MG wont supply that diversity well.
hope that helps somewhat