Great work and much luck to you packn
Actually they went from peats to 1 gal(3qts soil) to 3 gal (apx 2 gal soil) then the 9gals..I transplanted into 9 gal (34L) pots. I didn't use the pots to full capacity. 5 gals (19L) of soil was added. They were in 3 gal(11.4L) pots using about 2.5 gals (9.5L). So now they grow in a total of @7.5 gals (28.5L) of soil.