Just to clarify on the Miracle Gro they actually do quite a few different products and the one I have used is the soluble all purpose fert.

It just a fert so its not going to kill your babies unless you over do it. Personally on these type of soluble ferts I always go a little under the recomended amount per litre so maybe 3/4 of what they recommend.

I normally don't fetilise at all in the first couple weeks either as if you are growing in a decent soil it will have enough nutes for this period.

As the other guys have said you do need to sort your light out as you just don't have enough watt's to get much return on all this grow time. I did a couple of grows under Floro tubes when I was first growing and the yield is so low its barely worth it.

Get yourself an HPS or MH light from a grow shop and the yields increase massivily. Ok you might spend £200 on a good light but once you are self sufficent for weed it seems like a very small out lay.