How to grow calibrachoa (million bells)

Members of the Solanaceae family, calibrachoas are native to south America, where they grow in scrub and grassland and have a sprawling habit. In the 1990s, breeders produced hybrids that were perfect for growing in gardens. Recent breeding has produced plants that are particularly good at coping with the unpredictable British weather. Calibrachoas look similar to petunias, but they are usually classed as a different species.

As calibrachoas are hybrids, they can't be grown from seed. They are usually bought as small plants at the garden centre in late spring – you'll often find them sold as plug plants (very young plants) or in packs or trays, which represent excellent value. Calibrachoas won't survive the cold temperatures of autumn and winter in the UK, and are usually discarded at the end of the season.

How to grow calibrachoa

Calibrachoas are best planted in containers –they look lovely tumbling over the sides of hanging baskets, pots or window boxes in summer. Buy them as plug plants in early spring or as garden-ready plants from late spring to summer. Keep well watered and feed every couple of weeks with a high potash feed. Compost the plants at the end of the season.

More on growing calibrachoa:

• Plants for hanging baskets
• Wildlife-friendly hanging basket
• Begonia, petunia and calibrachoa hanging basket

Calibrachoa: jump links

• Planting calibrachoa
• Caring for calibrachoa
• Propagating calibrachoa
• Growing calibrachoa: problem-solving
• Buying calibrachoa
• Best calibrachoa to grow

Where to grow calibrachoa

Calibrachoas need a sheltered spot, in sun or very light shade. They will grow in the ground, but it's best to grow them in containers or hanging baskets with other summer annuals, letting them trail over the edge.

How to plant calibrachoa

Calibrachoa are available to buy as plug plants or young plants in spring. Plug plants can be more cost effective but you'll need to grow them on in a frost-free place before them planting out. Pot them individually into 9 cm pots and grow on a well-lit windowsill or in a heated greenhouse.

Harden off (gradually acclimatise your plants to outdoor conditions) and plant out after the last frosts have passed – usually in late May.

• How to harden off plants

Plant in multi-purpose compost, around the edges of a large pot or hanging basket that has crocks at the bottom and a drainage hole so that any excess water can drain away – it's a good idea to mount a pot on the ground on 'pot feet' so that any excess water can drain away. You could add slow-release plant food granules or tablets when planting. Water well after planting.

• How to plant a hanging basket

Caring for calibrachoa

Keep your calibrachoa plants well watered – this could be as much as once a day in very hot weather. Make sure you let any excess drain away – calibrachoas suffer when sitting in waterlogged soil.

Feed every couple of weeks with a high-potash feed from midsummer.

You don't need to deadhead calibrachoas plants as they're 'self-cleaning' – they automatically drop their spent flowers. Pinching back each stem (removing the growing tip) will encourage more bushy plants that will produce more flowers. Compost your plants at the end of the season.

How to propagate calibrachoa

Calibrachoa are hybrids and therefore do not produce seeds. Many plants are trademarked, which means that, while propagation through softwood cuttings is possible, it's technically illegal. It's best to buy young plants at the garden centre in early spring – they are excellent value.

Growing calibrachoa: problem solving

Poor blooming could be due to too much shade – calibrachoa plants need around six hours of sunlight a day to flower well. Erratic watering can also cause the plant to stop flowering well. If flowers are petering out at the end of summer, you could try cutting the plant back by half and giving it a feed.

Wilting can be due to lack of water or very high temperatures. If your plant is still wilting after watering, it may be suffering from root rot, in which case the plant is best removed and composted. Grey mould on the leaves is also a sign of overwatering.

Aphids can be a problem, but only in large numbers. You may find that wildlife, such as birds and wasps, will take care of aphids for you. If not, spray with an organic insecticide based on fatty acids.

Green or yellow leaves are a sign that the plant needs feeding.

Sticky leaves are a feature of calibrachoa plants and this is nothing to worry about.

Best varieties of calibrachoa to grow

• Calibrachoa 'Can Can' series – hundreds of bi-colour blooms in a wide range of colours that cope well with poor UK summer weather.
  Height x Spread: 25cm x 30cm
• Calibrachoa 'Million Bells Series' – masses of trumpet-shaped flowers that cope well poor summer UK weather. Available in a wide range of colours.
  H x S: 25cm x 30cm