N.W. Pot Size and timing question.

I live in Eastern Washington and have 3 ladies (18'' Height 9'' in Width) in 5.5'' cups ready to transplant and 12 ladies (6-12'' Height 4-9'' Width) in keg cups ready ro transplant as well. Obviously an outdoor grow. My questions are...
1.) The 3 large clones i want to put into large fabric pots (20+ gal.).

2.) The other clones that are 4 weeks behind in 15 gal. fabric pots.

The more soil the bigger the plants. We use nothing under 100g for our outdoor, mostly 200g or 4'x4' 18" tall beds. Smart pots are a great idea, just remember the bigger the pot, the bigger the plant

Great advise. 20 gallons is really minimal for an outdoor grow but it will work. When your plants start getting big and needing more rootspace, you can literally just dump a couple bags of soil around the pot in a mound, maybe pile some rocks around to make a boarder to hold it from running off when watering. Then the roots can grow right through the pots. You can also work the soil under the pots and let the roots grow down into the ground.