Sprint 330 and Sprint 138 are strong chelated forms of iron that maintain and protect iron availability. Sprint 138 is more effective when soil pH is higher than 6.5. Apply as soil drench at 3-5 oz./100 gal. (rinse excess off leaves & flowers immediately following drench.) For specific usage information including pictures please ask for a copy of the bulletin titled, "Iron Deficiency in Greenhouse Crops" by Paul Fisher, UNH and Rick Yates, Griffin Greenhouse Supplies.