mulch is just anything you lay over the soil to keep weeds from growing (the bad kind lol)and to keep sun out haha we have the same purple plant problem my la woman started doing it to I thought it was magniesium deficiency but I am feeding it plenty of Epsom salt but yeah calcium from calmag (calcium and magneiesium sub nute) is probly are problem I cant afford calmag at the moment but I am about to giving it 1/2 milk and 1/2 water yes its a plant fertilizer but I don't know if the plant will get the calcium it needs. also as for lighting 5000k is plenty Attachment 290831