Yeah, he's probably serious. That's a pretty basic question that shows you haven't extended any effort whatsoever in finding the answer on your own. People don't want to answer completely remedial questions that should take you less than 2 minutes to search for the answers on your own.
Now, I shouldn't even answer you, but I will because at least you weren't rude with your questions. In the future use the search function, read the faqs, and google that shit before you ask questions...no one wants to spoon feed you, little baby bird.
Cannabis flowering is triggered by the reduced daylight time of late summer/autumn. A photoperiod of 12 hours on and 12 hours off is generally used to force a plant in vegetative growth to flower. So yes, your 12 hour light cycle is causing the plant to flower. 18 hours on and 6 hours off is generally accepted as a good cycle for vegetative growth. Don't worry about the electric bill too much. That's an extra 6 hours, at 300watts. If your electricity costs $0.08 per killowatt hour, then it will cost you $0.14 more per day. No big deal.
Now, as far as suggestions. You can grow cannabis with miracle grow and liquid fertilizers, but it is not the easiest way. You will not be successful if you don't know what the plant requirements are, so search and read about cannabis' requirements and choose fertilizers that will cover the plants needs in all stages of growth, because the plant needs nutrients at different levels at different stages. This means you will need more than one type of fertilizer. I've know several people who have grown great plants with miracle grow soil, so it CAN be done. I suggest that you read up on organic growing, because, in my opinion, it is actually easier in many ways. Do some research. Funny word, 'research', the main part of it is SEARCH. I suggest you do that.
