I was planning on supplementing with a cheap blurple light actually. I'm planning on journaling the growGet them in.. get them growin.. see how they go M8.. learn as you go.. and if you can get another light to go with your mars 600 that would be great.. even a cheaper end blurple to supplement.. I don't think 20g per plant is impossible by any means with that light but it will depend on all your other factors as well.. if your temp and humidity in the room is bang on most the time they'll have the best chance possible. Journal it if you can and lots of peeps on here will guide you through.