With its stunning cascades of blossoms, calibrachoa became a popular fixture in gardens across America after it was introduced in the 1990s. Native to South America, this beautiful flowering plant is often called Million Bells or Superbells — both are actually trademarked cultivar names — because of its plentiful and tiny bell-shaped blooms that look a lot like miniature petunias. Thanks to its trailing growth pattern, calibrachoa is ideal for hanging baskets or container gardens and thrives when grown under the right conditions.
Calibrachoa grows in small groups or mounds of flowers that only reach 3 to 9 inches in height. Instead of growing up, it grows out, reaching up to 2 feet in width, with trailing stems up to 30 inches long. Its foliage consists of small, narrow leaves bright green in color. The flowers come in a dazzling array of colors including red, yellow, magenta, bronze, white, purple, and blue. Some are bicolored, spotted, or streaked, adding even more visual interest to window boxes and hanging baskets.
Calibrachoa likes moist, well-draining soil and prefers full to part sun. It is happy in summer and fall gardens in almost any USDA growing zone but is only winter hardy in zones 9-11. In these milder climates, calibrachoa may be grown as a perennial, but it is otherwise mostly planted as an annual. They are day-neutral, meaning that they cheerfully display their blossoms all season long no matter how many hours of sunlight occur each day.
Most gardeners purchase small calibrachoa plants to get their flower gardens started. However, they may also be propagated from stem cuttings. For best results, find a stem with small buds that haven't flowered yet. Measure at least six inches from the tip before you make your cut and remove any leaves. Place the cuttings gently into well-draining potting soil. Adding peat moss may be helpful. Position them where they will receive bright light and keep them warm (but not hot) and well-watered. In a few weeks, new roots should begin to develop.
Though you could grow Million Bells in a garden bed, it's most spectacular in containers as a "spiller" or as the star of a hanging basket or window box. Choose a rich potting mix with a pH of 5.0 to 6.5. Place the potting mix in your container before gently removing your calibrachoa plant from its pot. These plants are often sold root-bound, so be careful not to damage it as you remove it. Plant them 6 to 12 inches apart and press the soil down around the base of each plant, then water well.
Calibrachoa prefer full sun for the most prolific blooms, but they are also tolerant of partial shade. In warmer climates, your calibrachoa might even bloom longer if you select a location that receives shade for part of the dayThat's to prevent the plant from drying out and keep it thriving. For best results, try to select a location that will receive at least six hours of sun each day.
For the most part, calibrachoa is easy to grow with few major pitfalls. However, there are a few things gardeners should keep in mind. First, overwatering your plants can cause root rot. Wilting after watering may be a sign of this. If you grow calibrachoa in a container, it is harder to overwater since containers with good drainage dry out more easily. Calibrachoa may also become stressed during intense summer heat. Stressed plants are more susceptible to frequent pests like spider mites and aphids. Moving the plant to a shadier location may help it avoid heat stress.
Because calibrachoa is such a prolific bloomer, you do need to fertilize the plant regularly to help it achieve peak performance. Starting your plants in rich soil should mean you only need to feed them every few weeks. The easiest way is to use a diluted liquid fertilizer during the regular watering time. Make sure to choose one that provides sufficient nitrogen to keep foliage looking fresh.
Calibrachoa comes in so many beautiful colors that it can be hard to pick a favorite. However, these varieties each have something special:
Calibrachoa has also been bred to express many interesting flower patterns including veils, stripes, and stars. Here are a few of the most popular patterned varieties:
Calibrachoa really shines as the "spiller" element in a decorative container. Combine it with a tall, showy "thriller" plant and a variety of fillers with beautiful foliage to create a stunning display. With so many varieties, it's easy to find a calibrachoa type no matter what large plant you choose for your container. Suggested "thrillers" include fountain grass, calla lilies, and elephant ear.
The pretty plants also provide a lot of flower power, so you might choose a filler with interesting foliage instead. Suggested fillers include coleus, caladium, and heuchera.
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