is that miracle grow ur talkin about? cause ive got that, blue 1? most people say dont use MG its not good enough... i say its better than F-all... but id get new stuff.. 1/2 strength wud mean if they say put 1 little mg measuring spoonfull to 1 litre for example.. then u put half a spoon..... etc etc... not that ur using mg.... but same difference.. read the labels n jus half it n half it agen for 1/4 strength etc.. how many liters to a gallon is it 5? so if its 1 spoon a liter u make it halfspoon per liter if ur halfdosing.. .... 2 1/2 spoons a gal?? hope thats of some use... no doubt some pro will jump on me.. feel free!