If your growing in soil use pots around 30 litres or more autos can get huge root systems if grown right. I top the plant around 6 set o leaves . Folar Spray every week with trace elements spray and I just use seed raising mix no fancy soils . I find keeping it simple gives me bigger yields I also give them 1/4 strength nitrogen feeds as well as flowering feeds during flowering . I never check for ph I just watch the plant and see how it reacts to the feeds I give it. You should give that a try onetime and see how it goes. Here's a couple of more pics 6 foot tall strawberry pie auto and another gorilla cookies auto