Hi
@Aiiogrow! With photosynthesis strains and soil, I like to plant them in a 1L pot, then wait for the roots to spread by the bottom of the container (AirPot), this is usually done by week 2-3. Then I transplant into a 7-9L pot, for the whole veg stage. Once I have the switch date in mind, I transplant them in their final container (12-15L) 10 days before switching in flowering mode. It's up to you, you could plant them directly into their final container, but if you want massive roots you should wait until it's almost rootbound in the 1st container. Once transplanted, roots will explode horizontally and vertically. Hope this will help, keep us up-to-date and happy growing 👊