Stackswell bigger leafs, fatter stems, faster growth Stackswell is a special blend of humic acids, calcium sugars and magnesium – these are the foundation for your plants diet – encouraging faster growth bigger growth and fatter stems. Bigger leafs, Fatter Stems, Faster Growth. What is Stackswell? It’s a super concentrated growth powder. It can be used by the gram for reservoirs or mixed into a concentrate for dosers and fertigation systems. Stackswell is a Cation Exchange enhancer and Root and shoot growth stimulator.