For anyone that is thinking about having a garden tower, John from Growing Your Greens made this great video to show us how to make the potting soil that you need to fill the tower with. He adds so many things that will make what ever is grown in the tower super nutritious. He adds multiple rock dusts so that the plants can get loads of vitamins and minerals as well as compost and other things. Its a long video but it shows how light and airy the soil should be and he shows how to plant it as he fills it.