A good idea is to transplant to a larger pot once flowering has commenced and sex has been determined. The plants roots will expand alot during the "stretch" and throughout the flowering cycle. The more room you give them the better off your plant will be. A healthy root structure underneath the soil is directly correlated to bigger yeilds above ground.
Thanks Roo.................I guess I will be transplanting in a week or 2. I just transplanted from 2 to 3 gallon pots and change the lights to 12/12. The roots were jammed packed. This obviously does not leave much room in the 3 gallon pots for the roots to grow. I thought my plants were growing slowly, must be due to the limited room for the roots to grow.
That's the rule of thumb for determining pot size when container growing. Of course it's not written in stone. There are tons of growers who grow bigger plants with less soil.
In hydro it's 5 gallons of nutrient solution per plant minimum. Once again...not written in stone.
I've always liked 5 gallon buckets for the plants I flower. I keep mom plants in 1 gallon square pots.
My progression is usually:
1) germinate in a yogurt cup.
2) transplant in 7 to 12 days into a 1 gallon pot.
3) veg until sexed in the one gallon pot, then take cuttings.
4) Once rooted, the clones go into 5 gallon buckets for a lil veg, then flower.