MICROBE-LIFT/BLOOM & GROW Iron supplement is a highly concentrated (10,000 mg/L) ferrous iron (Fe2) gluconate. It should be used where additional iron is needed to prevent iron deficiency, or where signs of iron deficiency are present. This includes weak thin stems or yellowing between the veins of the leaf (chlorosis). Use together with other BLOOM & GROW™ plant supplements for healthy, lush plant growth.