Yes, even though you are growing in soil, you'll end up needing a cal mag supplement. All of my grows have been in soil, and all of my plants have needed cal mag treatment. Now, I do use LEDs, which seems to increase the plant's appetite for calmag, so you may not need it in as high of doses as I used, but you will end up needing it. If you ask 100 different growers about feeding schedules, you'll probably get 100 different answers. During my first grow, I was told constantly to "listen to your plant." Didn't know then, but I do know now what they were talking about. That schedule may sound good now, but your plant might not agree with it. Or, maybe your plant thrives off that schedule at first, but later on, you may find that you need to adjust the schedule. It all depends on your plant.