How to Grow Campanula

Campanula is an attractive ornamental garden flower. Often coming in blue and purple shades, as well as occasional white varieties, the plant’s pleasing bell shaped flowers have inspired its informal name of bellflower.

Campanula has an abundant flowering habit. The plants can happily flower all summer long. This longevity has helped to make the plant a mainstay of flower beds and borders. Smaller varieties work equally well in living walls, rockeries and container gardens.

Whatever your growing situation there is a variety of campanula for you. They are also pleasingly easy to grow. Here is your complete guide to growing campanula.

Commonly known as bellflower, after the flowers’ distinctive shape, these are pleasingly easy to grow ornamental plants. 

Varieties of Bellflower

A member of the campanulaceae family, there are over 300 different types of campanula. Some are perennial while others are annual or biennial. They can also differ in shape, color and size.

One of the most common varieties is the Wall Bellflower. Originating in the Dalmatian region of Croatia it is also known as the Dalmatian bellflower. A perennial plant, the wall bellflower has a robust, low-growth habit. This makes it ideal for smaller gardens and containers. A relatively late flowering plant, its dark blue flowers tend to emerge towards the end of summer.

An increasingly common cultivar is  Miss Melanie (C. portenschlagiana). A relative newcomer to the market, its extended flowering time and compact growth habit is helping to make it one of the more popular varieties.

Americana is another popular campanula variety. Originating in the United States, Americana is usually grown as an annual. In warmer regions, gardeners will be able to grow it as a biennial. Also known as Tall Bellflower this variety can reach up to 6 inches in height. An attractive plant, its light blue or violet flowers open into a flat shape which is less bell-like than other varieties.

Rubriflora (C. Punctata) is a popular clumping variety, producing flecked purple and pink hanging bell shaped flowers. Reaching about 1 ft in height it is a great choice for raised beds and borders.

Clustered Bellflower (C. Glomerata) is so called because the flowers of this variety tend to cluster together. Each cluster can have as many as 15 different flowers in shades of white and violet-blue on its long stems. This cultivar is pleasingly long lasting, clustered bellflowers can flower for up to 3 weeks from late spring until early summer. It is also a great cut flower.

Trailing Bellflower (C. Poscharskyana) is an attractive trailing plant. Originating in Yugoslavia this is a robust variety which thrives in both warm and cold climates. In the colder USDA zones, you will need to cut down and lift the plants in the fall. Store the plants inside over the winter months before replanting in the spring after your last local frost date has passed. Interestingly the foliage of the plant is edible, making a great salad dressing.

Canterbury Bell (C. Medium), is a biennial variety. As the name suggests it produces large bell-shaped flowers in a range of shades including white, pink and blue. In ideal conditions the plant can reach up to 3ft in height.

One of the most popular cultivars, Canterbury Bells produce a pleasing, large flower in a range of colors. 

The lavender and purple-blue flowers of Creeping Bellflower tend to droop down towards the ground. This gives the impression that the plant is creeping through your garden. Like the trailing bellflower the plants foliage is edible. The roots and shoots are also edible.

Harbell (C. Rotundifolia) is a perennial wildflower commonly seen in many parts of the Northern Hemisphere. The heart-shaped, bright green foliage of the plant complement its violet-blue flowers. A wildflower, this is a very robust variety that survives the harshest of conditions.

The cultivar Nettle-Leaved Bellflower (C. Trachelium) is a herbaceous perennial with eye-catching red stems and nettle-like foliage. Thin hairs cover the stems, foliage and lilac-blue flowers of the plant. Folklore has it that this cultivar can also cure sore throats, hence the common name throatwort.

Dwarf varieties such as Fairy Thimbles (C Cochlearifolia), Blue Gown (C. Poscharskyana), and White Harebell (C. Collina) are all ideal for container gardens and rockeries.

A pleasingly compact cultivar, Harebell is ideal for smaller gardens and containers. 

How to Grow Campanula

Campanula is one of the easiest plants to grow. Thriving at temperatures over 30 ℉, the plants grow best in USDA zones 4 and higher. With a little extra care and patience, gardeners in USDA zone 3 can also grow the plants. In cooler climates you will also need to provide some extra protection during the winter months.

Campanula plants do best in well draining soil and full sun positions. Some varieties, such as wall bellflowers, can cope with some shade.

Pleasingly robust, the plants can tolerate periods of drought. The soil pH profile doesn’t matter, these flowers tolerate both acidic and alkaline soils. However, you should avoid planting in soils that are extremely acidic or alkaline. Amending the soil is an easy option if your soil is too extreme for ornamental flowers. If you want to know the profile of your soil, a number of reliable testing kits are available.

Starting from Seed

You can purchase campanula bedding plants from most garden centers. These are ready to be planted straight into a flower bed or container. However, learning how to grow campanula from seed is pleasingly easy. It also allows you to choose from a wider variety of plants. Be warned, campanula may not flower in its first year after sowing from seed.

Sow seeds in the spring, directly into the ground as soon as the last frost has passed. Before sowing dig the soil over to loosen it. Work in a little organic matter such as homemade compost.

Water the soil and sow the seeds. Dampening the soil before sowing encourages the seeds to stick in place. Cover with a thin layer of soil.

Protect your seedlings from slugs and snails. Covering the seedlings with a mini cloche, such as the GrowAway Reusable Small Mini Greenhouse, is a great way to protect young plants and seedlings. These also help to maintain temperature levels sheltering delicate young plants from unexpected temperature changes.

Seeds should germinate within 3 weeks. In cooler conditions it may take a little longer.

How to Grow Campanula Undercover

Seeds can also be sown indoors, in trays or containers 8 to 10 weeks before your last predicted frost. Fill the trays with fresh, moist potting mix and sprinkle seeds along the surface. Cover with a light compost layer. Place the trays in a warm, sunny position.

Don’t allow the soil to dry out, regularly moisten the soil with a gentle spray. A bottle such as the Bar5F Clear Spray Bottle provides a fine, gentle spray that won’t harm delicate seedlings.

When the germinated seedlings have produced at least two true leaves they can be potted on into their own containers. These can then be hardened off and planted outside once the weather is warm enough.

Growing from seed often allows you access to a wider variety of plants. Make sure you keep seedlings damp, warm and protected from slugs and snails.

Transplanting into Beds

Whether you are purchasing plants ready for transplanting or growing your own from seed, the plants should always be hardened off before planting. While the plants are acclimatizing dig over the flower bed, removing any weeds and stones. Work in some organic matter, such as homemade compost. This helps to enrich the soil as well as improving drainage.

Plant in holes about one inch deep. Space plants 15 to 18 inches apart, depending on the requirements of each variety. Water and mulch lightly. This helps the soil to retain moisture as well as suppressing weed growth. Taller varieties may also need a stake or other form of support.

Planting in Containers

Campanula can also be grown as part of a container garden. The container should be clean and have drainage holes in the bottom. Fill with a loam-based compost. Work in some grit or sand to further improve drainage. Water retaining crystals can also be added to help the plants stay hydrated during dry periods. Alternatively use a self-watering pot. Plant as you would in the ground.

Repot once the plant has outgrown its container. This is best done in early spring, before new growth begins to emerge. Roots protruding from the drainage holes in the bottom of the container is a clear sign that the plant needs to be repotted. Growth slowing or the soil drying out more quickly than usual are other signs that the plant needs to be repotted.

If you do not need to repot the plant add a fresh top layer of compost each year. This gives the plants a nutrient boost.

Caring for Campanula

Once established, campanula is an easy to care for addition to your garden.

Water

Campanula, once established, is surprisingly drought resistant. Water regularly when the plants are growing. Allowing the soil to dry out during this period may cause the flower to drop its flowers.

While the plants require moisture, they also dislike sitting in wet soil. Instead of watering frequently, water deeply. A soil moisture meter helps you to accurately monitor the condition of the soil.

Reduce watering when the plant is not actively growing, during the fall and winter.

Harvesting rainwater is an easy way to keep your plants hydrated without using lots of water.

Remember plants in containers require more frequent watering than those growing in the soil. 

Fertilizer

Try not to over fertilize the plants. This can cause them to become leggy as well as encouraging slugs and snails to attack the plants. Fertilize once in the spring, as new growth emerges, and again in the summer.

When you do feed, apply a fertilizer high in phosphorus. This encourages flowers to form. Avoid nitrogen rich fertilizers. Nitrogen encourages foliage production, often at the expense of flowering. A bone meal feed is a natural source of phosphorus.

Liquid fertilizers are easily incorporated into a watering routing.

Pruning

As you learn how to grow campanula you will realise just how maintenance free these pleasing plants are. For example, there is no need to prune the plants.

Dead or damaged foliage should be removed with a sharp garden scissors. This keeps the plant looking neat and healthy.

Deadheading spent blooms encourages new flowers to form. It also helps to prevent self-seeding varieties from freely spreading throughout the garden.

Pinching out flower tips encourages new blooms.

Companion Planting

An easy going plant, campanula goes well with other cottage garden plants. Campanula flowers look particularly attractive growing alongside hibiscus plants. The plants also look good in containers, rockeries and trailing over raised beds or walls.

How to Propagate

Propagation is best done by seed. Allow spent flowers to go to seed, once the seed pods ripen harvest carefully. Store the seeds in a paper envelope in a cool, dry location and sow the following spring.

You can also divide large clumps of campanula. This is best done in the spring or the fall. To divide, carefully dig up the root system of the plant. Brush away any dirt and inspect the root system for signs of disease or damage.

If the root system appears healthy, carefully divide it with a sharp, clean knife. Once cleanly separated, re-plant the roots in the soil or containers.

Another method of propagation is to take basal cuttings. As well as campanula, other flowers such as delphiniums can also be propagated by taking basal cuttings.

Basal cuttings can be taken when the first green shoots appear. With a sharp knife cut down at the point where shoots emerge from the root system. Cut as close to the base of the plant as you can. There should be some solid, woody type tissue at the base of the cutting. Trim down or cut away some of the leaves.

Place the cuttings in a container filled with moist, fresh, multi-purpose compost. Cover the container with a large plastic bag or place in a mini-greenhouse. Place in a bright, sheltered spot. Don’t worry if initially the cuttings wilt or appear to struggle. This often happens. They will soon pick up again. Roots will form, if cuttings are successful, within a few weeks.

Common Pests and Problems

Campanula is a largely problem free plant. Many pests tend to leave these attractive plants alone. The exception is snails and slugs. These common garden pests tend to target ornamental flowers such as campanula. Protect your plants, particularly in early spring as they are establishing themselves.

Should other pests such as aphids attack your plants, infestations can be removed with an application of neem oil to the plants foliage. The pests can also be washed away with a blast from a hosepipe.

Campanula plants can fall victim to rust. This displays itself by causing orange, rust-like patches to emerge on the underside of foliage. Cut affected plants down to ground level and cover with fresh compost. When new growth emerges it will be rust-free.

Powdery mildew can coat the foliage of plants, often causing the leaves to turn yellow. Powdery mildew is usually caused by dry soil and humid conditions. Spacing the plants properly so that air can circulate alleviates or prevents the issue. Regularly weeding around the plants as well as cutting back any other plants that are too close also helps.

Another way to prevent powdery mildew is to only water around the base of the plant. If, when watering, you can keep the foliage of the plants dry you reduce humidity levels. This helps to prevent mildew from forming.

Severe infections should be cut away and destroyed. Don’t place diseased cuttings on a compost heap. Fungicides may also need to be applied.

Other issues such as Anthracnose and Botrytis can also target the plants. Properly spacing and watering campanula significantly reduces the chances of these issues occurring.

Attractive and easy to care for, bellflowers are a reliable addition to any garden or outdoor space.

Learning how to grow campanula is a pleasingly easy process. It is also a great place to start if you are new to gardening.

Campanula plants are attractive, easy to care for additions to the garden. The plants work in a range of planting schemes and can also be used to edge paths or fill containers on sunny balconies.

Once established campanula is a pleasingly trouble free plant. It reliably provides you with colorful flowers throughout the spring and summer months.