If you're water-conscious (or just don't want to give much time and attention to your rooftop sanctuary), you might want to incorporate succulents. They've got swollen, water-storing leaves, so they're an ideal choice if you want a no-hassle garden. Even if you've got a black thumb, you can find a succulent that works for you -- there are thousands of species that grow all over the Earth, from deserts to jungles. These supremely hardy plants will add interest to your garden with their gorgeous colors: silvery blues, inky purples, shocking greens and soft yellows. Succulents fare well in containers or raised beds, and we like grouping different colors and shapes for a more eye-catching arrangement.