December 11, 2024 · Regina Meehan

Calibrachoa: Ultimate Growth and Care Guide

Discover the Best Guide for Growing Calibrachoa. Want a splash of vibrant color in your garden or hanging baskets? You can purchase Calibrachoa plants online today!

Introduction to Calibrachoa 

Calibrachoa, often called Million Bells, is a beloved flowering plant known for its vibrant blooms and cascading growth habit. While it’s often mistaken for a miniature Petunia, Calibrachoa is its own distinct species. Its adaptability to containers, hanging baskets, and garden beds makes it a staple in gardens seeking continuous color and charm throughout the growing season. With flowers that attract hummingbirds and butterflies, it’s an essential choice for gardeners aiming to cultivate a lively, pollinator-friendly space.

I first planted Calibrachoa in a hanging basket many years ago, and it instantly became a favorite for its easy care and non-stop blooms. Its ability to attract hummingbirds and butterflies makes it a must-have for my patio garden.

Characteristics of Calibrachoa

Calibrachoa is known for its trumpet-shaped flowers, each about one inch in diameter. Available in nearly every color imaginable—from soft pastels to deep, saturated hues—it also features striking bicolors and patterns like speckles and stripes. This variety of colors allows for endless design possibilities, whether you’re looking to create monochromatic elegance or a dynamic, colorful display.

The plant’s continuous blooming habit sets it apart. Unlike many other flowering plants, Calibrachoa’s spent blooms drop off naturally (a self-cleaning trait), which reduces the need for deadheading. This low-maintenance feature is a significant reason why gardeners return to Calibrachoa year after year.

Size and Growth Habit

Calibrachoa typically grows 6 to 12 inches tall and can spread up to 24 inches wide. Its trailing growth habit makes it ideal for hanging baskets, window boxes, and elevated planters, where it’s free to spill over the edges, creating a lush, full appearance. In garden beds, it can also be used as a ground cover, filling in gaps with its dense foliage and vivid blooms. This makes it a versatile choice for a variety of gardening layouts, from vertical gardens to container designs.

Leaves and Flowers

The foliage of Calibrachoa is just as important as its flowers when it comes to overall plant health and appearance. Its small, oval to lance-shaped leaves are typically 1 to 2 inches long, growing alternately along the stems. The leaves have a soft, slightly fuzzy texture and a natural resistance to pests. This natural resistance, combined with the plant’s sticky foliage, keeps it looking healthy throughout the growing season.

The trumpet-shaped flowers, though small, are produced in abundance, completely covering the plant with vibrant color. They’re available in a wide spectrum of colors, from classic yellow, pink, and purple to more unusual shades like coral, salmon, and black. The self-cleaning nature of the blooms allows for minimal maintenance while ensuring the plant remains visually appealing all season long.

Is Calibrachoa Annual or Perennial?

The answer depends on your growing zone. Calibrachoa is a perennial in USDA Zones 9-11, where it can survive mild winters and continue growing year-round. In Zones 5-8, however, it’s typically grown as an annual due to its sensitivity to frost. For gardeners in cooler climates, it’s extremely important to wait until all danger of frost has passed before planting Calibrachoa outdoors. 

Note also that in Zone 8, Calibrachoa may act as a tender perennial. However, gardeners must be patient and wait for last year’s calibrachoa to begin sending forth new growth. Not all species are as hardy, and containers located near to a home’s foundation, thereby receiving the residual warmth of the home, are more likely to be “perennial” Calibrachoa in Zone 8.

Best Varieties of Calibrachoa

Selecting varieties with strong genetic foundations significantly enhances the likelihood of a thriving, vibrant garden display. We recommend varieties based on Results from Independent Evaluations conducted by esteemed horticultural research institutions.

The following Calibrachoa varieties have earned the highest accolades, achieving top ratings of 4.8 to 5.0, and are widely regarded as the best choices for gardeners seeking reliability, color, and vigor.

Best Variety #1: Calibrachoa Million Bells

Known for its profuse blooms in a variety of colors, this classic variety is a favorite for hanging baskets and container gardens.

Best Variety #2: Calibrachoa Super Bells Lemon Slice

This Proven Winners variety features vibrant yellow flowers with white stripes, creating a cheerful display.

Best Variety #3: Calibrachoa Cabaret

With compact growth and bold flower colors, Cabaret is perfect for mixed containers and small garden spaces.

Best Variety #4: Calibrachoa Super Bells Dreamsicle

This variety produces stunning orange blooms, making it a standout choice for autumn-themed gardens or colorful summer displays.

Recent advancements in plant genetics have led to a significant increase in the development of new Calibrachoa species over the past three years. Breeders have focused on creating cultivars that are not only more compact but also deliver an abundance of blooms that persist over an extended growing season. These top-rated cultivars stand out for their superior performance, boasting improved resistance to heat and disease—a marked improvement over older varieties. It is important to note that these elite cultivars are patent-protected, and unauthorized propagation is strictly prohibited.

How to Grow & Care for Calibrachoa

Calibrachoa is a versatile, low-maintenance flowering plant known for its continuous blooms throughout the growing season. This adaptable beauty can be grown in hanging baskets, containers, or as ground cover. To ensure optimal growth and health, follow these essential care guidelines:

Planting Calibrachoa

Plant Calibrachoa after the final frost of spring to provide it with the best chance to thrive. Use well-draining soil enriched with organic matter to supply essential nutrients. Space plants 12 to 18 inches apart to allow for airflow, which minimizes disease risk and encourages robust growth. For hanging baskets, place three plants in a 10-inch basket, adding one additional plant for every 2-inch increase in basket size. For containers or troughs, maintain a spacing of about 6 inches between plants to allow them to spread naturally.

Sunlight Requirements

Calibrachoa requires 6 to 8 hours of direct sunlight daily for peak blooming. While it can tolerate partial shade, excessive shade will reduce flower production. In areas with extreme heat, afternoon shade can prevent plant stress and wilting. Adequate sun exposure ensures vibrant colors and steady blooms throughout the season.

Soil Requirements

Calibrachoa prefers light, well-draining soil rich in organic material. The ideal pH range is slightly acidic, from 5.5 to 6.5. Soil that is too alkaline can hinder nutrient uptake, resulting in poor plant health. For heavy clay soils, incorporate compost or soil conditioner to improve drainage. For container growth, a high-quality, lightweight potting mix with good drainage is essential to prevent waterlogged roots and promote healthy growth.

Watering Needs

Consistent moisture is key for healthy Calibrachoa growth, but overwatering must be avoided. Water deeply and allow the top layer of soil to dry slightly before the next watering. Hanging baskets and containers dry out faster than garden beds, so they may require daily watering, especially in hot weather. During extreme heat (90°F or higher), check soil moisture twice daily to avoid dehydration.

Fertilizer Needs

Calibrachoa is a heavy feeder that benefits from a consistent supply of nutrients. Apply a 6-month slow-release fertilizer at the time of planting for long-term feeding. To support steady blooming, supplement with a water-soluble fertilizer every 1 to 2 weeks throughout the growing season. Choose a fertilizer with a balanced or phosphorus-rich formula to encourage continuous flowering. Be cautious with nitrogen-heavy fertilizers, as they promote leaf growth at the expense of blooms.

Pruning & Maintenance

Calibrachoa’s self-cleaning nature means spent blooms drop off naturally, eliminating the need for deadheading. However, to maintain a tidy appearance and promote fresh growth, trim back leggy stems or pinch back one stem per week. This method encourages bushier growth and increased flower production. For plants that begin to look sparse in midsummer, a more significant trim will revitalize the plant’s shape and vigor.

Common Pests

Calibrachoa is generally hardy, but it can attract certain pests, including aphids, spider mites, thrips, and budworms. Each of these pests can affect foliage and flowers, but timely intervention can prevent severe damage. Here’s how to manage them:

  • Aphids: These sap-sucking insects leave behind sticky honeydew, which attracts ants and fosters sooty mold. Use insecticidal soap for immediate control and neem oil for long-term prevention. Aphid populations can increase rapidly, so reapply treatments within 7 days to disrupt their lifecycle.
  • Spider Mites: Often present in hot, dry conditions, spider mites cause tiny yellow or white speckles on foliage. Apply neem oil to affected areas, ensuring thorough coverage under the leaves. Repeat treatment weekly if infestations persist.
  • Thrip: These pests cause leaf discoloration and can be managed with Spinosad, a natural bacterial insecticide. For prevention and control, use insecticidal soap in combination with neem oil.
  • Budworms: Budworms feed on tender flowers, often causing plants to stop blooming. Use Bacillus thuringiensis (BT), a biological control that targets caterpillar larvae. Ensure flowers are completely covered and within a week, your plant will begin budding and blooming again.

Since many pests hide on the undersides of leaves, ensure complete coverage when spraying treatments. Direct the spray beneath leaves to effectively target hidden pests and prevent reinfestation.

Common Diseases

Calibrachoa is not generally susceptible to fungal diseases. Maintaining good airflow, avoiding evening watering, and ensuring soil drains properly will deter fungal diseases.

Common Mistakes

When it comes to growing Calibrachoa, even experienced gardeners can encounter challenges. Here are the five most common mistakes to avoid:

  1. Allowing Plants to Get Too Leggy
    Failing to pinch back Calibrachoa regularly leads to leggy, sparse growth that diminishes the plant’s visual appeal. To maintain a lush, full appearance, pinch back one branch or stem from each plant weekly. This encourages denser foliage and promotes continuous blooms.
  2. Allowing Plants to Dry Out
    Calibrachoa grown in containers is especially vulnerable to drying out, particularly in temperatures exceeding 90°F. If the soil dries out completely, the plant’s leaves may yellow, and flowers will fade prematurely. Repeated cycles of drying and "crashing" can permanently damage the plant, making it unsightly and difficult to revive.
  3. Failing to Fertilize Adequately
    Even nutrient-rich soil can only sustain plant growth for a limited time—typically 90 days. Without additional feeding, plants may exhibit poor growth and reduced blooms. Regularly apply a slow-release fertilizer at planting time and supplement with liquid fertilizer every 1-2 weeks to keep plants performing at their best.
  4. Overwatering
    Watering without checking the soil’s moisture content can lead to oversaturation, which causes root rot. Planting in containers without proper drainage or in dense, compacted soil further exacerbates this issue. Before watering, test the soil—if it’s still moist, hold off. Proper drainage is critical to Calibrachoa’s long-term health.
  5. Providing Insufficient Sunlight
    Calibrachoa requires full sun (4-8 hours of direct sunlight daily, depending on climate) to produce abundant flowers. Insufficient sunlight results in weak, leggy growth and a lack of blooms. For best results, plant in a location with full sun exposure and avoid shady spots that will compromise flowering.

Common Misconceptions

Several misconceptions about Calibrachoa persist among gardeners. Clarifying these misunderstandings can lead to better plant performance and overall success.

  1. Calibrachoa is Just a Smaller Petunia
    While Calibrachoa and Petunias are related, they are distinct species. Calibrachoa’s flowers are smaller, self-cleaning, and require less maintenance than traditional Petunias. Unlike Petunias, which often require deadheading, Calibrachoa’s spent blooms naturally fall away, keeping the plant looking fresh.
  2. Calibrachoa Only Thrives in Containers
    Although Calibrachoa is often seen in hanging baskets and window boxes, it’s also an effective ground cover. When planted in well-drained garden beds with full sun, it spreads to form a colorful, low-growing carpet of blooms.
  3. Heat Causes Calibrachoa to Stop Blooming
    When Calibrachoa stops blooming during the peak of summer, many gardeners assume the heat is to blame. However, the true culprit is often the budworm—a pest that feeds on tender flower buds, interrupting the bloom cycle. To resolve this issue, apply Bacillus thuringiensis (Bt) to the affected plants. Blooms typically resume within a week of treatment.

Using Calibrachoa in the Garden

Calibrachoa’s vivid colors and cascading growth habit make it a versatile and dynamic addition to both garden beds and container plantings. With blooms available in nearly every shade, it delivers continuous color throughout the growing season. This adaptable plant is a popular choice for hanging baskets, window boxes, and garden borders, offering a lush, trailing effect that pairs well with other plants.

Hanging Baskets

Calibrachoa’s trailing habit makes it an excellent choice for hanging baskets, containers, and window boxes. The cascading display of colorful blooms adds depth and movement to elevated garden spaces. To ensure healthy growth, use a high-quality, well-draining potting mix that retains moisture while allowing excess water to escape. 

Position containers in areas that receive full sun (4-8 hours daily, depending on climate) to promote vigorous blooming. Regular pruning is essential to control leggy growth; pinching back one stem weekly encourages a fuller, denser display and increases flower production. With proper care, Calibrachoa transforms patios, porches, and balconies into vibrant, colorful spaces.

Garden Borders

For edging garden borders and pathways, Calibrachoa offers continuous color and texture throughout the growing season. Its compact growth habit and prolific blooms create tidy, vibrant edges that enhance any garden landscape. Space plants evenly along borders for a cohesive and well-balanced look. To support healthy growth, plant in well-draining soil, and amend with compost to improve fertility and structure. Full sun exposure (4-8 hours daily) ensures optimal flowering and prevents legginess. Prune as needed to maintain a compact shape and promote additional blooms. Calibrachoa’s neat, colorful presence makes it an ideal choice for defining garden paths and walkways.

Mixed Plantings

Calibrachoa’s versatility allows it to pair beautifully with annuals, perennials, and ornamental grasses in mixed garden beds. Its trailing habit and vibrant blooms provide a striking contrast to upright plants, enhancing the overall aesthetic of the planting design. Use it as ground cover beneath larger shrubs or as a filler between taller plants to achieve a layered, textural look. Proper spacing is essential to avoid overcrowding and ensure each plant has adequate access to nutrients and water. By promoting healthy airflow and minimizing competition for resources, gardeners can achieve balanced, thriving plant combinations. With thoughtful placement, Calibrachoa’s bold color and lush growth add visual interest and lasting beauty to any garden.

Experience A Calibrachoa Color Explosion

Looking to grow Calibrachoa in your garden? Here at Garden Delivery, we have the finest Calibrachoa plants, cultivated with superior genetics and sourced from the most trusted origins in the industry. We’re committed to providing you with detailed plant information, including performance rankings, so you can make an informed choice. Add this vibrant, show-stopping plant to your garden today and experience the beauty it brings to your outdoor spaces!

Frequently Asked Questions

Do Deer Eat Calibrachoa?

Deer tend to avoid Calibrachoa. It is considered deer resistant primarily due to the characteristics of its foliage and flowers. The leaves of Calibrachoa are small, with a slightly tough texture and a glossy surface, which deer find less appealing compared to softer, more tender foliage. Additionally, Calibrachoa flowers are trumpet-shaped and relatively small, which are not as enticing to deer as larger, more fragrant blooms.

Is Calibrachoa Poisonous To Dogs?

Calibrachoa plants are generally considered non-toxic to dogs. The American Society for the Prevention of Cruelty to Animals (ASPCA) lists Calibrachoa as non-toxic to dogs, cats, and horses. This means that if dogs ingest parts of the plant, such as flowers or leaves, it is unlikely to cause significant harm. However, as with any plant, ingestion of large quantities may still cause gastrointestinal upset, such as vomiting or diarrhea.

Do Hummingbirds Like Calibrachoa?

Yes, hummingbirds are attracted to Calibrachoa due to its bright, colorful blooms and abundance of nectar. The small, trumpet-shaped flowers resemble the natural shape of many wildflowers that hummingbirds feed on, making them an appealing food source. Placing hanging baskets, containers, or garden beds filled with Calibrachoa near areas where hummingbirds frequent can increase your chances of attracting them. For maximum appeal, choose bold colors like red, orange, or pink, as hummingbirds are naturally drawn to these hues.

How Long Do Calibrachoa Last?

Calibrachoa plants can last for several months, typically thriving from spring through fall in most climates. As warm-weather perennials in USDA zones 9-11, they can grow year-round, but in colder zones, they are treated as annuals since they cannot survive frost. With proper care, including regular watering, fertilization, and pruning, Calibrachoa will bloom continuously throughout the growing season. 

Do Rabbits Eat Calibrachoa?

Rabbits typically avoid eating Calibrachoa due to its slightly tough, sticky foliage and unappealing taste. While not entirely rabbit-proof, Calibrachoa is considered a "rabbit-resistant" plant, as most rabbits prefer softer, more palatable plants. However, in times of food scarcity or during the early stages of growth, rabbits may still nibble on the leaves or flowers. To protect your Calibrachoa, consider using natural deterrents like garlic spray, planting rabbit-resistant companion plants, or placing a barrier or fence around your garden beds.

Are Superbells and Calibrachoa The Same Plant?

Superbells is a trademarked brand name under Proven Winners, referring to a specific line of Calibrachoa known for its enhanced performance, larger blooms, and stronger resistance to disease. While Superbells are Calibrachoa, not all Calibrachoa are Superbells. The term "Calibrachoa" refers to the species as a whole, encompassing a wide range of varieties and cultivars, of which Superbells is just one premium option.

Are Calibrachoa Easy to Propagate?

While it is technically possible to propagate Calibrachoa, most varieties sold in the U.S. are patented or pending patents. Propagation of these protected varieties is illegal until the patent expires, typically 20 years from the date of issue. The legal protections on propagation ensure that breeders can continue to innovate and provide gardeners with the highest quality plants available.