Flourish Iron™ is a highly concentrated (10,000 mg/L) ferrous iron (Fe+2) gluconate supplement. It should be used in those cases where the iron requirements exceed that which can be delivered by Flourish™ at the recommended dose or signs of iron deficiency appear (such as short and slender stems or yellowing between veins.) Contains no phosphate or nitrate.
Plants are able to much more easily derive a benefit from Flourish Iron™ than from EDTA-iron sources because all EDTA iron is in the ferric (Fe+3) state. Since plants require iron in the ferrous (Fe+2) state, additional physiological energy must be expended in order to extract the ferric iron from EDTA-iron and then convert it to the ferrous form.
Use 1 capful (5 mL) for each 200 L (50 gallons*) or as required to maintain about 0.10 mg/L iron. For smaller doses please note that each cap thread is about 1 mL. Use an iron test kit to monitor iron concentrations. Use as needed to combat signs of iron deficiency (usually seen in new growth) which include: chlorosis (yellowing) of tissue between veins and short and slender stems.