How to Grow & Care for Calibrachoa (Million Bells®)

How to Grow & Care for Calibrachoa (Million Bells®)

This showy flowering plant was introduced in the 1990s and has been an annual hit ever since. Calibrachoa is commonly known as Milion Bells or Trailing Petunias. The plant and blooms closely resemble petunia but the overall plant size is much smaller.

Ideal for hanging baskets, containers, or use as a ground cover, calibrachoa is an easy-care plant that you should try in your garden this summer.

Calibrachoa Care and Info

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Growing Location

The plants grow best in a full sun location but will last longer if provided with a little afternoon shade. Calibrachoa will continue blooming later into the hot summer months if planted in a location that will give them morning sun and afternoon shade. A happy plant will bloom from June until frost.

Soil Requirements

The plants thrive in soil that is rich in organic material. The organic material will allow the soil to drain quickly yet remain consistently moist.

Calibrachoa will not tolerate soil that has a high pH. If your soil has a high alkaline, lower it with an application of sulfur, sulfuric acid, or aluminum sulfate before planting.

When To Plant

Start seeds indoors 6-weeks before the last predicted spring frost. Plant seedling outdoors in the early spring after all danger of frost has passed.

Prepare the soil by working in plenty of compost (amend the soil with pH lowering additives if needed) and loosening it to the depth of 8-inches if planting outdoors.

If using a container or hanging basket, select one that is at least 8-inches deep and equally as wide. Use a potting soil mix that contains compost and has a pH level of 6-7.

How To Start Seeds

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Use a seed tray or bio-degradable grow cups to start seeds indoors. Use potting soil that contains compost to fill the selected seeds containers. Lightly sprinkle the top of the potting mix with calibrachoa seeds and gently press the seeds into the soil.

These seeds will germinate better with a little light exposure so do not cover them completely.

Gently mist the top of the soil until it’s saturated. Place the seed container in a warm location that is away from direct sunlight.    Keep soil moist at all times.

The seeds will germinate in 10-14 days. As soon as you see green sprouts above the soil, move the seed container into direct sunlight or place under a grow light. The new seedlings will need 12-16 hours of bright light each day to develop into healthy plants.

Thin seedlings to 2-inches apart after they develop their second set of leaves. Continue keeping the soil moist and the seedlings in bright light during the day.

When the seedlings are 4-weeks old feed them with a weak solution of water-soluble plant food.

Begin the hardening-off process when the seedlings are 6-weeks old. This process allows the seedlings to adjust to life outdoors before they are transplanted.

Move the container to a sheltered place outside for a week. Be sure to protect them from wind and direct sun on the first day. Lengthen their exposure time to the sun each day.

If frost threatens at night, cover the seedlings or bring containers indoors, then take them out again in the morning. This hardening-off process toughens the plant’s cell structure and reduces transplant shock and sun-scald.

How To Transplant Million Bells®

What Is Calibrachoa Plant

To transplant the seedlings you have started indoors or when transplanting a plant from the nursery container into a different one, prepare the soil first.

Dig a hole for each plant large enough to accommodate the root ball. Space each hole 6-10 inches apart.

Gently remove the plant from the container and set it in the hole level with the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand leaving a slight depression around the plant to hold water.

Water thoroughly, so that a puddle forms in the soil depression you created. This settles the plants in, rids the soil of air pockets, and results in good root-to-soil contact.

Apply Mulch

Calibrachoa needs consistent moisture and cool soil. A 2-inch layer of organic mulch applied around the base of each plant will benefit the plant. The mulch will also help prevent weed growth so the flowering plant does not have to compete with weeds for moisture and nutrition.

The mulch will slowly decompose and improve soil fertility and structure.

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Feed plants that are growing in-ground once a month during the growing season. Use a balanced organic plant food that will promote strong roots with plenty of above-ground growth and bloom.

Calibrachoa plants that are grown in hanging baskets or planters may need to be fed more often to stay productive. Feed plant water-soluble plant food mixed at one-half the recommended rate every 10 days.

Pruning The Plant

Calibrachoa is a self-cleaning plant and will drop its spent blooms quickly. You won’t have to deadhead the old blooms.

You can prune the plant by pinching off any wayward trailers or stems to keep the plant looking neat and compact. Pruning also encourages new growth and more blooms.

Stem Propagation

Near the end of the growing season is the best time to propagate calibrachoa. It can be overwintered indoors so you can have a strong, healthy plant to set outdoors in the early spring.

The plant is easy to propagate through stem cuttings. Locate a stem that has small buds but no blooms on it. Cut that stem 6-inches back from the tip. Remove all the lower leaves from the stem. Insert the cut end into a small container that is 50% potting soil and 50% peat moss. Water well and place in a warm location that is bright but not in direct sunlight.

Keep the soil moist and new roots will develop on the buried stem in 2-3 weeks.

Seed Collection

Seed pods will develop under some of the blooms. Blooms that have been pollinated by bees, birds, or butterflies may develop viable seed pods that can be harvested for planting next season.

As the blooms fade and die back, check for a small swollen bump under the bloom. This is the seed pod and can be snipped off and saved. Collect the pods just before they turn brown or they will burst open and the seeds will be lost.

Place the seed pods on a tray in a single layer and allow them to dry for 1-month. Break open the dried seeds pods over white paper toweling. Pick out the largest bits of pod and debris and save the seeds in a paper envelope. Label the envelop and store it in a cool, dry location until planting time.

Collect more seeds than you need. Calibrachoa is a hybrid, so some seeds may not germinate. Those that do are unlikely to grow true to the parent plant but instead will resemble one of the grand-parent plants.

Mature Plant Size

Calibrachoa Hanging Basket

Calibrachoa plants will reach a mature height and width of 6-12 inches. The plant produces long trailers that are loaded with colorful blooms. The plant can be pinched back and kept at the desired size.

The multitude of blooms are 1-inch in diameter and are in shades of blue, red, pink, white, bronze, yellow, magenta, and purple.

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Does Calibrachoa come back every year?

Calibrachoa like most other trailing perennials can come back year after year. Pinching out the old flowering stems at the end of the season, will promote growth and help make the plant bushier. 

Calibrachoa is an annual in the cool spring and fall zones and a tender perennial in the warmer winter zones.

Do you deadhead Calibrachoa?

Deadheading of Calibrachoa is not necessary except for the spring growth. 

Mature plants can be cut down to about half the height for a more compact plant and a continual flush of blooms. Deadheading is a good way to keep your Calibrachoa looking fresh and to keep new blooms coming. It will also allow it to grow and flower faster and more profusely if you regularly deadhead it. 

How long does Calibrachoa last?

Calibrachoa can last 2 to 3 years, if planted in well-drained soil, kept well-watered, and fertilized regularly.

Does Calibrachoa like sun or shade?

Calibrachoa will grow in full sun or part shade. Being a tropical plant, the more sun it gets, the better. Red and yellow varieties need the most sun to keep their color full, so plant them in an area that gets a lot of sun.

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