Hello, depending on if you are growing or using fresh roses,If you plan to "GROW" black roses ,mix two teaspoons black dye to 5 cups water,once a week water with black water,add Miracle grow to produce as many blooms as possible also will be larger blooms! If using cut flowers the other suggestion was correct,cut at angle in a bowl of cool water (the first thing the flower will "inhale" will be water not AIR ,resulting in a tipping head)Then add the dye, strong mixture.This also works with other white flowers.Try mixing your own colors,pink flowers with green dye,yellow with red and so on .Good luck !! Sue of TWIN-CITIES GREEN TEAM 651-226-0103