Green Planet Pro Cal 2-0-0 [1L 5L 20L] Green Planet Pro Cal is a valuable source of supplemental calcium and magnesium. Why is Pro-Cal so great for your plants? It is an excellent supplemental source of Calcium, Magnesium and Iron, which plants need to grow strong and healthy. Plants engaged in rapid growth can often come up short on these essential elements, so supplementation is a great idea. Green Planet Pro Cal 2-0-0 Benefits Thickens cell walls Helps form calcium pectate Fully chelated iron Important source of magnesium Noticeable size increase Improved enzyme function Coco coir approved Powerful formulation How to Use It? 5 ml/gal throughout the vegetative stage. 7 ml/gal for the flowering stage Stop using prior to the flush week.