darren rovell explains what all the fuss is about. >> reporter: is there anything hotter than kale?s in every salad, dominating lettuce bins, popping up in places we could never imagine. >> kale is king. >> reporter: the kale economy has turned it into a money plant. there are kale smoothies in juice bars. and kale martinis in trendy new york restaurants. there's even kale nail polish. gwyneth paltrow has devised a use for kale in recipe after recipe on her blog. first lady michelle obama has planted kale in the white house garden. >> this trend came out of nowhere are. it's incredible how fast this item became popular. >> reporter: the demand for this leafy green can be seen here in california's salinas valley. also known as the salad bowl of the world. that's where church brothers has doubled the amount of kale they planted in each of the last three years. >> look, all you can see, as far as you can see. that's how much people like it. >> honestly, i can't see the end of this. >> reporter: whole foods sells more than 22,000 bunches of kale per day in its stores. and mentions of ka