How to Plant, Grow, and Care For Calibrachoa

Calibrachoa, also known as million bells, is an easy-going flowering annual related to petunias. The small bell-shaped flowers appear on long stems of bright green foliage.

Calibrachoa tends to grow to about 10 inches tall and has a trailing habit, which means it will continue to grow in width after it has quickly reached its maximum height of 10 inches.

About Calibrachoa

Often confused with petunias due to their very similarly shaped flowers and growing habits, the two are entirely different species. However, like petunias, calibrachoas are very easy-going and require little to no maintenance throughout the growing season.

These plants are super tough. Calibrachoas’ flowers are smaller than petunias, and the plant tends to have a tidier growing habit.

Calibrachoa has become one of the most popular annual plants amongst home gardeners over the past few years and is available in just about every color. Also known as million bells or trailing petunia, calibrachoa grows lush trailing stems that make it a great addition to patio planters or hanging baskets.

History and Cultivation

When calibrachoa was first discovered, it was classified as a petunia. Over the years, as more varieties have surfaced and the plant world has evolved, million bells has begun to set itself apart from its close relative the petunia. In 1985, it got its own classification, deeming it as an entirely different plant genus called Calibrachoa.

Native Area

Calibrachoa plants are native to South America, Mexico, and five southwestern US states, where they grow in grasslands and shrubby woodland areas.

They stay low to the ground and grow into a carpet-like appearance. They are known to reseed themselves in these natural habitats, allowing them to spread to other locations. 

Propagation

In cultivation, calibrachoa plants do not produce many seeds. Therefore, they are primarily reproduced by vegetative cuttings. Cuttings are generally grown and established into plastic nursery pots and sold at garden centers. This is most likely how you will purchase your calibrachoa. 

Planting

The best time to plant calibrachoa is in late spring, once the weather officially warms up and there is no chance of chilly (below 50 degrees) nights. As mentioned previously, calibrachoa is generally reproduced from cuttings that are rooted and grown in nursery containers. 

Once you have chosen your varieties and purchased transplants from your local garden center, it is time to plant those bad boys! Once you transplant million bells, these low-maintenance plants don’t require much work. There are a few things to note when deciding where and when to plant calibrachoa. Let’s dig into the details!

Transplanting

The best time to plant million bells is in the early spring or in the fall in mild climates. If growing indoors in a container, you can plant calibrachoa at any time. Some plants can be heavily rooted into their plastic containers, so I like to roll the pot in between my hands to loosen it up. 

1. Dig a hole about twice the pot’s width.
2. Be sure the hole is deep enough to fit the entire root ball plus a few inches.
3. Set the plant in the hole.
4. Fill in the extra space with the soil you removed earlier.
5. Lightly tamper down and water thoroughly.

If you are planting multiple plants into one pot, leave about 3 to 6 inches between each plant. If you are planting directly into the ground, depending on how lush you want the plantings to be, leave about 6-12 inches in between plants.

How to Grow and Care for Calibrachoa

Native to warmer regions such as South America, calibrachoa is a relatively low-maintenance plant. With modern growing methods, cultivated calibrachoa is almost guaranteed to succeed in your garden.

Sunlight

Like petunias and others in its family, calibrachoa loves full sun. If you plant this annual in an area that receives even a few hours of shade, it will hinder its ability to flower. You might see the leaves begin to turn yellow over time. 

Plant calibrachoa in an area that receives sunlight for the majority of the day (6 to 8 hours of direct sun). 

Water

Calibrachoa should be watered frequently, but it does not like its soil to stay moist for long periods. Let your soil dry out in between waterings, but do not let the soil get so dry that it becomes light brown and chalky.

The best way to check if your plants need water is to feel the soil. If you stick your finger a few inches down and the soil sticks to your skin, it is not time to water yet! 

When it comes time to water containers, water million bells plants thoroughly. Add water to the container until it drains out of the bottom of the pot. This will ensure you water the entire root ball and help flush out any built-up salt or nutrients.

Soil

If you have heavy clay soil or notice that it does not drain well while watering, it’s best to amend it before planting. Amend tough, compacted soil with compost or a light planting mix to break it up and ensure proper drainage upon watering. 

Climate and Temperature

Calibrachoa can be planted in the spring once the weather warms up. They do not like temperatures under 55 degrees, so it is best to plant them when average daily temperatures exceed 60 degrees Fahrenheit. 

Native to warmer regions of the world, these plants can withstand hot and dry climates and are super easygoing, making them a great option for gardeners in many regions. 

The plant can be grown as a warm-weather annual in zones 3-8. Million bells remains perennial in zones 9-11. As long as it has enough light, it can be grown as an indoor houseplant just about anywhere.

Fertilizing

Calibrachoa appreciates frequent fertilizing every couple of weeks using a water-soluble fertilizer. You can also add a slow-release fertilizer to patio pots or hanging baskets, providing a small amount of nutrients each time you water. 

Calibrachoa is prone to iron deficiency which causes the new leaves of the plants to turn yellow. Fertilizing regularly will prevent this from occurring. If you suspect an iron deficiency in your plants, fertilizing will reverse the issue in a short couple of weeks.

Maintenance

This easygoing plant is very low-maintenance and does not require deadheading or pruning. Sometimes, plants can become leggy or overgrow their area later in the growing season. Light pruning is a simple solution for this. Simply trim the unwanted growth with clean pruners to tidy the plant. 

Pests and Diseases

Calibrachoa is relatively issue-free but can still fall victim to certain pests and diseases over time. Most pests or diseases that appear in calibrachoa are environmental and can easily be prevented or eliminated once identified.

Pests

Most pest infestations occur in nurseries or garden centers, so it is pertinent to inspect plants before bringing them home. When shopping, keep an eye out for damaged foliage, spots on leaves, and other red flags to ensure you purchase the healthiest plants possible!

Aphids

Aphids generally appear on the backsides of leaves or on leaf nodes close to stems. Aphids can range in appearance depending on their life stage, usually appearing white, green, or brown in color. They are attracted to calibrachoa due to the plant’s slightly sticky texture. 

Aphids suck nutrients out of the plant’s leaves, and if the infestation is severe, they will cause the plant to turn yellow and eventually die. Remedies for aphids can come in many forms:

• Remove the highly infested parts and dispose of them in the trash.
• Apply a drench or spray of soapy water to kill the pests.
• Many chemical or insecticidal soaps and sprays are also available to treat aphids. 

Although a chemical spray sounds daunting, this might be the best option for severe infestations.

Fungus Gnats

Fungus gnats can be a pain to identify and even more difficult to eradicate. They are tiny black bugs that live and reproduce in the soil, so keeping an eye out for them can be challenging. 

You might see little black bugs flying around the base of your plants. This is a good indicator of fungus gnats. Another way to check is to shake the pot and see if any bugs fly out of the soil.

Fungus gnats thrive in wet soil, so allowing your soil to dry out between waterings is crucial to avoid fungus gnat infestations. If you notice you have fungus gnats, you have a couple of options to get rid of them:

• If feasible, repot your plant in fresh, healthy soil.
• Cut back on watering.
• Apply a chemical drench (specifically formulated for fungus gnats) directly to the soil.
• Dangle yellow sticky traps above the plant.

Diseases

Both diseases mentioned in this article are prevalent in wet, humid conditions. Calibrachoa does not like being overwatered, and allowing the root ball to dry out in between waterings is essential.

Root Rot

Root rot occurs when the soil does not have a chance to dry out in between waterings. When left too wet, a bacteria or fungus can form underneath the soil, infecting the plant’s roots.

The roots will begin to decay underneath the soil. If left untreated, the rot will climb upwards and cause the leaves and stems of the plant to turn yellowish brown and die. 

Treat root rot with a fungicide drench, or repot your plant into fresh soil.

Botrytis Blight

Botrytis blight generally forms in cool and wet conditions and appears as a fuzzy gray mold on leaves and stems. This mold will spread rapidly and cause the plant to rot and turn grayish-brown. 

Some ways to prevent botrytis from attacking your plants include:

• Ensure your plant gets enough sun (6-8 hours daily).
• Allowing the soil and plant to dry out for brief periods.
• Removing any ugly or damaged foliage immediately.

Calibrachoa Varieties

There are millions (pun intended) of million bells varieties available nowadays. I won’t list all of them in this article, but I would like to mention a few of my personal favorites. 

‘SuperbellsⓇ Tropical Sunrise’

‘Tropical Sunrise’ is a beautiful variety that hosts pink and yellow striped flowers. It adds such an interesting color scheme to any planter and never disappoints! You can only purchase this patented cultivar from an accredited nursery, and it should not be propagated by cutting.

‘Chameleon Blueberry Scone’

This variety is exactly what you’d expect: a faded blue color that transitions into a pastel yellow in the center, making it appear bicolor. This contrast is accentuated when next to dark foliage or yellow flowering plants.

‘MiniFamousⓇ Double Orange’ 

‘Double Orange’ provides bright orange color and a velvety appearance but doubled. The trumpet-shaped flowers are the same size but appear as a double, ruffled bloom. 

Plant Uses

Calibrachoa can be planted almost anywhere if the area receives full sun and has good drainage. Due to its size and shape, landscape borders or hanging baskets are the most popular plantings with calibrachoas.

Containers

Due to their habit of trailing and spreading, calibrachoas make dazzling additions to combination planters and hanging baskets. Make sure to plant calibrachoas with other plants that require full sun – such as petunias or verbena. Add grasses or sweet potato vines to planters to create contrasting foliage.

Landscape

Due to their compact growth habit, calibrachoas make great landscape borders or mass plantings to add a pop of color. When planting million bells in the landscape, ensure that other plants won’t shade them out and that the soil has great drainage.

Companion Plants 

Million bells can be planted in a container with almost any other sun-loving, flowering annual. If planted in the landscape, plant it in front of taller plants so that it does not get shaded out. If planting in hanging baskets or pots, plant this annual at the edge to allow the vines to trail out of the container.

Juncus Grass

Grass is a great companion for million bells in the landscape and in containers. It grows about 12 inches tall, making it a great middle layer in the landscape or a centerpiece to a patio container. There are many varieties of juncus grass available, with different colors, sizes, and textures.

Salvia

The tall, trumpet-shaped flowers make a great contrast when planted in containers and landscape borders. Salvia attracts pollinators and thrives in heat and full sun. They bloom all season long, from late summer up until the first frost.

Petunias

Petunias are a great partner for million bells for many reasons. Not only do they have the exact same growing requirements, but they come in so many different varieties and colors. You can’t go wrong! I love the ‘Petite Charmer‘ and ‘Garden Party‘ seed blends from Botanical Interests.

Lantana

Lantana grows a few inches shorter than calibrachoa, so it should be in between or in front of other plants in the landscape. These heat-loving annuals have warm-colored flowers and prefer hot, dry climates.

Frequently Asked Questions