The greens we get (particularly some of the winter spinach) can be pretty dirty. Give it an initial rinse and then remove the stems and soak the leaves in plenty of clean water. I use my salad spinner, placing the leaves in the basket and filling the bowl with water. This allows me to soak it for a bit to allow the dirt to soften and dissolve, agitate the greens, and then let the dirt settle to the bottom. Then I lift out the basket and repeat until the rinse water is dirt free.