Calibrachoa, also known as million bells, is one of the most popular plants for growing outdoors in containers. The plant comes in a rainbow of colors, in solids and two-tones, stripes, patterns, and stunning double blooms. Calibrachoa is a prolific bloomer and produces 1-inch blossoms that resemble tiny petunias. The compact leaves are oval-shaped and a bit sticky. Although it is a short-lived perennial in very warm climates, Calibrachoa is grown almost everywhere as an annual. The plant is not hard to care for, but paying attention to its needs will keep it blooming from spring well into fall. While it can be planted in garden beds, the plant fares much better in containers.