Emily Hurley I've wondered that myself. I love the look of these, but I have really bad luck keeping plants alive. :)

Glenna Partridge Garden Design This kind of hanging terrarium which has an air plant (tillandsia) in it is easy. Air plants like to be watered about once every ten days. Submerge the plant in water for about half an hour. Fill up the kitchen sink and pop them in or in a bowl of water. Take them out of their "bath" and let them dry a bit. Pop them back in the the little terrarium. These plants are often found in rainforests so they get regular moisture when they are growing out in nature. Like most houseplants they suffer when they have to survive in our dry indoor air. If you feeling a bit lazy or don't have time to do a proper soak, mist them well until you get time to give them a soak. I hope this helps!