I use to mix my own but going with foxfarms ocean forest i heard good things with this shit. just add 1/3 perlite -2 cups worm poo
1/3 coco fibers or peat moss
I've been doing some research and ocean forest mixture is good, but don't start seedlings in it, you need more pure soil then that, as ocean forest will burn seedlings.
I used Aurora Innovations Roots Organics Formula 707 last year and will use it again. I dug a whole and used 1 bag for each plant with great BIG PLANTS results. Here is a link. I will be using this year as well