| Common Name | Calibrachoa, million bells, trailing petunia, mini petunia |
| Botanical Name | Calibrachoa group |
| Family | Solanaceae |
| Plant Type | Herbaceous perennial flower often grown as an annual |
| Mature Size | 6–12 in. tall, 12–24 in. wide |
| Sun Exposure | Full sun to part shade |
| Soil Type | Moist, rich, well-drained |
| Soil pH | Acidic |
| Bloom Time | Spring to fall |
| Flower Color | Coral, yellow, orange, red, pink, blue, purple, burgundy, lavender, cream |
| Hardiness Zones | 9–11 (USDA); grown as an annual in all zones |
| Native Area | South America |
Calibrachoa Care
Here are the main care requirements for growing calibrachoa.
- Plant calibrachoa seedlings in the spring after the last frost in rich, moist soil, and place them 6 inches to 1 foot apart.
- Give calibrachoa at least four to six hours of full sun.
- Water calibrachoa well, sometimes twice daily in the heat, but do not waterlog the soil.
- Feed this plant a slow-release fertilizer.
Light
Calibrachoa blooms best with at least six hours of full sun but tolerates partial shade—especially in warmer areas. Insufficient sun exposure typically results in reduced blooming.
Soil
Calibrachoa likes fast-draining potting soil, so make sure your pot has good drainage. When planting in garden beds, amend with organic material to ensure richness and make sure the soil drains well. Mulch is recommended to keep the soil moist and the root system cool.
Water
Calibrachoa needs to be kept well hydrated but not water-logged. Heat, wind, and lack of humidity can cause soil to dry out quickly so you may need to water calibrachoa twice daily.
Add water only after the top inch or so of the soil dries out. Check if your plant needs water by sticking your finger into the soil to the second knuckle. If the soil feels dry at your fingertip, water deeply until it drains out of the bottom of your pot.
Temperature and Humidity
Calibrachoa is drought- and heat-tolerant, and even cold-tolerant. It prefers temperatures between 55 and 65 degrees Fahrenheit. A hardened-off plant can be brought outdoors in the spring as it can tolerate a mild frost. However, hot weather and dryness can stress the plant. Revive wilted foliage with a daily misting but misting can burn leaves facing the direct sun.
Fertilizer
Feed calibrachoa a slow-release fertilizer when planting and regularly use a diluted liquid fertilizer. Start with an organic, slow-release fertilizer mixed into your potting medium, and then give the plant a diluted liquid every couple of weeks throughout the season. Feed near the end of the season to promote late blooms. This plant is a heavy feeder but be careful not to over-fertilize—follow the directions on the label. Leaves turning light green or yellowish means the plant needs fertilizer or more sun.
Types of Calibrachoa
There are 28 different species in the Calibrachoa genus, but those used for garden cultivation are generally complicated hybrids derived from crossing various species. There are dozens of varieties of calibrachoa available in a vast array of colors, including:
- Calibrachoa ‘Cabaret Hot Pink’: This cultivar produces loads of bright pink flowers on trailing stems up to 8 inches long.
- C. ‘Cabaret Purple Glow’: This plant grows 12 inches wide and trails to 8 inches.
- C. ‘Million Bells Terra Cotta’: This million bells plant has orange flowers streaked with red and gold on stems trailing to 8 inches.
- C. ‘MiniFamous Double Blue’: The double flowers of deep blue-purple bloom on a trailing plant with 10-inch-long stems.
- C. ‘Superbells Pomegranate Punch’: Velvety-red flowers grow darker toward the center and mature at 8 inches tall.
- C. ‘Kabloom’: This is a series of hybrid plants that can be grown from seed and are available in pink, white, red, yellow, and deep blue.
Pruning
Calibrachoa is considered a “self-cleaning” plant, meaning it doesn’t need to be deadheaded to continue blooming. However, it will benefit from a serious cutting back toward the end of summer, along with a boost of fertilizer to reenergize the plant.
Propagating Calibrachoa
Calibrachoa plants grown in gardens are hybrids that produce few seeds. And because many of the varieties are trademarked hybrids, vegetative propagation through cuttings is technically illegal. If you do attempt to propagate through cuttings, the process is as follows:
- Cut a stem with small buds but no flowers at least 6 inches from the tip and remove lower leaves.
- Place cuttings in a 50-50 mix of potting soil and peat moss.
- Water the stem cuttings well.
- Set the pot under bright light.
- Keep the cuttings moist and warm (about 70 degrees Fahrenheit) until roots develop in about two weeks.
How to Grow Calibrachoa From Seed
Sow seeds indoors eight weeks before the last frost using a seed-starting kit.
- Sow seeds thinly, barely pressing them into the dirt so they have light to germinate.
- Mist the pelleted types of calibrachoa seed to dissolve the coating after they are pressed in the soil.
- Keep the soil moist at 70 to 75 degrees Fahrenheit and watch for seedlings in 10 to 14 days.
- Keep seedlings in plenty of light on a sunny windowsill or grow 3 to 4 inches beneath fluorescent plant lights for 16 hours in the daytime and off for eight hours at night (do not leave on 24 hours).
- Thin seedlings to one per cell when two sets of leaves emerge.
- Feed seedlings when they are a month old using a starter solution (half the strength of a complete indoor houseplant food).
- Harden seedlings before transplanting in the garden by moving them outdoors to a sheltered place for a week.
- Transplant hardened-off seedlings to the garden after the danger of frost has passed.
Potting and Repotting Calibrachoa
Most calibrachoa plants are badly root-bound when you buy them and there may not be much soil in the pot. Repot the plant into fresh general-purpose potting mix in a container of any material that has plenty of drainage holes. Loosen the root ball and add a slow-release fertilizer into the potting mix. These short-lived plants won’t require any more repotting.
Common Pests
Calibrachoa plants are extremely susceptible to aphids. Spray aphids off the plant with water, a water and dish detergent mix, or use neem oil.
On the bright side, deer don’t seem very interested in the stronger-scented calibrachoa, although this plant is not classified as deer-resistant.
How to Get Calibrachoa to Bloom
Bloom Months
Calibrachoa blooms from late spring into early fall.
What Do Calibrachoa Flowers Look and Smell Like?
Calibrachoa flowers are small trumpet-shaped blooms that resemble smaller petunias. They come in many colors from pastels to deeper orange and purple. Some calibrachoa types are more fragrant than others but they all usually have a lovely sweet scent.
How to Encourage More Blooms
To get the best blooms, don’t let calibrachoa dry out repeatedly. This plant is a heavy feeder so fertilize for more blooms. To get calibrachoa to grow bushier, pinch back tips of new growth to encourage branching and more blooms.
Common Problems With Calibrachoa
Besides battling aphids, yellowing leaves are the most common problem you’ll encounter with the otherwise easy-going calibrachoa plant. There are a few reasons for yellowing leaves:
- Iron deficiency (new growth will be yellow)
- Nitrogen deficiency (old growth will be yellow)
- Root rot
Root rot or mold infection can set in if these plants are overwatered. (Plants that wilt after watering may be suffering from root rot.) The best defense is to prevent these issues through good air circulation, proper water management, and good soil porosity.