The window light won't work out very well because it is coming up to fall and how often do you see seeds (outside) popping up in the fall? Not likely fall is time to harvest if you are using the sun as your only source of light!!!

If you want to have a good yield from your plants they need some sort of supplemental light as well as the sunshine!!!

Also I don't recommend using miracle grow... find an organic soil... I prefer fox farm ocean forest but also use roots organic (I used to mix my own soil but had 100 gallon hole to fill this year so I just bought the premixed soil.)
Once they get there true leaves they will need some sort of nutrients a basic grow will work (read you soil bag to see how 'hot' it is)