im using 5 gallon pots. if it is a photo period, i would not start it in 7 gallons. unless you have your own way of doing things. i think 7 gallons for the final pot would be ok. just to be sure ask another person. because it has been years since i have had a grow. believe me , made plenty of mistakes on this grow. one of them was starting it in to big of a pot. still having issues, getting nute deficiencies in tune. good luck