I dont know where you live, but in the northern hemisphere its heading into fall, that means less than optimal hours of light for veg, I am one of those guys that change lights from HID to HPS according to my phase.I do that to replicate the difference in the rays available at different times of the yr, So if you live in the northern hemisphere the sun isnt throwing out the best veg rays, its throwing out flowering rays. I think moving a plant inside and outside would be a huge pain in the ass. plus the fact you might not be exact on your timing each day and you may be susceptible to hermie. when you choose to grow indoors you become that plants god and these plants love a schedule and they will get all fucky fucky if you mess with a schedule. If I were you i would spend the $40 and get a cpl plant florescent at walmart ($
and a fixture ($30) and call it a day,, If you were dealing with a few plants I would suggest a 400 watt for veg, but with one plant you can easily get it to a good size with cheap florescents . Not to mention you are opening yourself up to outside problems, like mites etc..