sunporch experiment

This is my situation I began growing this winter at the end of january I have four female plants growing under two lamps one lamp is 100 watts with a 23 watt natural light bulb and the other one is a 60 watt lamp with an 11 watt natural light bulb also there in a window which cant be seen into so there getting natural sunlight i have them on a 18 hours light 6 hours dark routine its middle of febuary right now and I dont intend to harvest until the fall because as soon as spring/summer comes Im putting them in my sunporch and once fall comes I can harvest on the season change my sunporch keeps a higher humidity, temperature, and alot better ventalation because theres windows on 3 of the four sides and very well lit and with the summer comming I can continue growing it in its vegatative state...My questions are how successful do you think this method would be ? from what ive heard its best to grow your plants in there vegatative cycle as long as you can is this true? the total grow time will be about 6 months how big could I expect these plants to get and how large the yield? ballpark answers are fine and the plants are getting there proper nutrients and im using high quality soil and any added suggestions are appreciated