How to grow and care for begonias

Common types of begonia

1. Tuberous begonias (Begonia x tuberhybrida): Known for their large, colourful flowers in shades of white, yellow, orange, pink, and red. They thrive in filtered sunlight and can be grown in the ground or in pots. These begonias flower throughout summer and autumn.
2. Bedding begonias (Begonia semperflorens): These begonias flower abundantly in summer and autumn, producing masses of pink or white flowers. They prefer full sun and are ideal for mass planting in gardens or pots, providing vibrant, long-lasting displays.
3. Cane begonias (Begonia coccinea): Characterised by their tall, cane-like stems, reaching up to 2 metres. Many have highly patterned leaves and long-lasting flowers. They are usually grown indoors, but can be moved outside in summer into semi-shaded spots, away from harsh afternoon sun.
4. Rex begonias (Begonia rex-cultorum): Celebrated for their striking foliage in colours like green, black, pink, silver, and purple, often with metallic hints. The leaves may feature spots, stripes, or whorls. Usually grown as indoor plants, they prefer bright, indirect light, away from direct sunlight.
5. Elatior begonias (Begonia x hiemalis): These have green, heart-shaped leaves and brightly coloured flowers. They prefer moist, warm climates and are typically grown indoors or in fully shaded outdoor areas.

Top begonia plant care tips

1. Light: Most begonias prefer part shade or bright, indirect light. Bedding begonias can tolerate full sun.
2. Soil: They thrive in neutral to slightly acidic, well-draining soil.
3. Watering: Maintain moist but not waterlogged soil. Overwatering can lead to root rot, especially in tuberous or rhizomatous varieties.
4. Containers: Begonias grow well in pots. Use a peat-free multipurpose compost and ensure pots have good drainage.
5. Fertilising: Feed outdoor begonias fortnightly during the growing season with a liquid high-potash fertiliser, or add a slow-release fertiliser to the compost or soil when planting. Feed indoor begonias with a houseplant fertiliser.
6. Pruning: Begonias don’t usually need pruning. Deadheading isn’t necessary either but will keep the plant tidy and help prolong the flowering period. To deadhead begonias, snip the faded flowers off just below the bloom.

Essential shopping list for growing begonias

• Begonia plants or tubers
• Fertiliser
• Compost or soil improver
• Garden shovel
• If growing in pots: suitable potting mix, controlled-release fertiliser, and appropriate containers
• Mulch
• Pest control products, such as insect spray and snail & slug pellets

Where and when to plant begonias

Most begonias prefer a part or semi-shaded spot, although bedding begonias will also grow well in full sun. They can be grown indoors or outdoors, but need to be protected from frost and low temperatures in winter. Begonias prefer moist, free-draining soil that's neutral to slightly acidic (pH 6.0-7.0). Plant outdoors in late spring after all risk of frost is past.

Growing begonias in the garden

1. Planting: Dig a hole twice as wide as the original pot and the same depth. Gently remove the begonia from its pot, place it in the hole, and backfill with soil. Water well.
2. Mulching: Apply mulch around the base to retain moisture and suppress weeds.

Growing begonias in containers

1. Container choice: Select pots with good drainage, slightly wider and deeper than the nursery pot.
2. Potting mix: Use a peat-free multipurpose or ericaceous compost.
3. Planting: Remove the begonia from its pot, place it in the new pot, and backfill with compost. Water thoroughly. Place the pot in a sheltered, frost-free spot in the sun or light shade.

Planting begonia tubers

Growing begonias from tubers is easy to do. You can start begonia tubers indoors in early spring, so that they are ready to plant out after the frosts. 

1. Plant the tubers hollow side up, 2.5cm deep in individual pots filled with multipurpose compost. Water lightly and place in a warm spot at around 18°C.
2. Once leaves start to grow, pot the plants into larger pots.
3. Plant outdoors once all risk of frost is over.

How to care for begonias

Water your begonias regularly. Feed fortnightly during the growing season with a liquid high-potash feed such as tomato feed.  Regularly check for pests like aphids and treat them promptly. Deadhead spent flowers and damaged leaves to keep the plants looking tidy and encourage further flowering.

Overwintering begonias

Although begonias are perennials, they are not frost-hardy and need protection in winter if they are to come back year after year. To overwinter tuberous begonias, lift the tubers in autumn when the leaves start to yellow, remove the foliage, allow the tubers to dry, and store them in a cool, dry place over winter. Replant in spring after the risk of frost has passed. Bedding begonias are usually grown as annuals in the UK.

With a little care and attention, begonias can provide a stunning garden display, offering colour and interest throughout the growing season.

Common begonia pests and diseases

• Aphids: These small green or white sap-sucking bugs can attack soft new growth. Wipe off with a damp cloth, or spray heavy infestations with insecticide.
• Spider mites: Mottling on leaf surfaces and fine webbing on leaves and stems is a sign of spider mite infestation. This is most common on indoor plants, especially when the air is too dry around the plants. Move the plant away from other indoor plants to stop the pests from spreading and spray with insecticide.
• Powdery mildew: A fungal disease which causes a white powdery coating on leaves. Remove affected leaves. To reduce the risk of powdery mildew, water plants regularly and ensure good air circulation by not overcrowding plants in beds.

FAQs

Can you leave begonias in pots over winter?

You can leave begonias in pots over winter, provided you move the pots into a dark frost-free place before the first frosts. Stop watering over winter. Once new growth starts in spring, move the pots into the light and start watering. Move the pots back outdoors after the frosts have passed.

Are begonias poisonous to dogs and cats?

Begonias are moderately toxic to cats, dogs and horses if ingested. Although the most toxic parts of the plant are underground, it’s best to keep these plants out of reach of your pets.

When do begonias flower?

Outdoors, begonias flower over a long period from late spring well into autumn and often right up to the first frosts. Indoor-grown begonias may flower at any time of year, provided they have the right light and growing conditions.