Windowsill not so much.
A couple clip-on desk lamps with the BIGGEST BADDEST cool white CFLs you can find will work though!
It just occurred to me... outdoor growing involves lots of hiking and the growing gives you an excuse to make yourself get out and be all healthy and shit, and the hiking and being all healthy and shit is a good excuse for why you just HAVE to go hiking every saturday morning instead of hanging around the house where you can be conned into boring chores