Some are lucky enough to be born with green thumbs, but for the rest of us, those skills could often use some serious, ahem, cultivation. Enter, The Sill. Founded by Eliza Blank with the simple ambition of inspiring people to bring the outdoors in, this thoroughly modern online plant shop (and compendium of all things plant related) is just the thing for greenery-deprived urban dwellers. More than apartment eye candy, plants have been proven to boost creativity and productivity and curb stress and fatigue. But before you take the plant plunge, Blank shares a few rules of (green) thumb.