Height 15-60cm (6-24in)
Planting distance 38cm (15in)
Flowers early summer to early autumn
Rich, moist well-drained
Sun or partial shade
Tubers available late winter/spring
The tuberous begonia, with its vibrant scarlet, orange, yellow, white or pink blooms borne through the summer, is often regarded as the queen of bedding plants. It is ideal for adding summer colour to pots, window-boxes, hanging baskets and borders, in sun or shade. The half-hardy Begonia x tuberhybrida will grow happily outdoors during the summer, provided it is planted in a rich, moist but well-drained soil. The varieties developed from this hybrid are divided into four groups.
Multiflora non-stop varieties have clusters of small brightcarried well above the foliage. The plants grow 15cm (6in) high and have a compact, neat bushy habit that makes them excellent as bedding for and containers. The varieties come in a wide range of colours -some with unusual foliage colours as well. ‘Switzerland’ has deep orange-scarlet flowers and bronze leaves; ‘Mme Helene Harms’ has semi-double copper-yellow flowers, and ‘Bouton Rose’ is bicoloured pink and white.
Pendula varieties have a slender, trailing habit that makes them suitable for hanging baskets and window-boxes. From early summer till early autumn they bear an abundance of semi-double white, yellow, orange, scarlet, salmon or rose flowers, according to variety. Large camellia-flowered (double) varieties have blooms 7.5-15cm (3-6in) across. The plants reach up to 30-60cm (1-2ft) high and grow well in containers. An enormous number of varieties is on sale, offering almost every shade of orange, yellow, red and pink imaginable.
Fimbriata varieties are vigorous, weather resistant in spite of their fragile appearance. They bear fully double flowers with frilled petals and come in white and shades of pink, orange and yellow.
Start the tubers in late winter or early spring – hollow-side facing up – in 7.5cm (3in) deep boxes of moist peat substitute. Keep them at a temperature of 18°C (64°F). When leafy shoots appear, transfer them to individual pots of potting compost. Plant out in early summer in flower beds or containers, once the risk of frost is over. Fill the containers with a proprietary potting compost. Set plants 38cm (15in) apart and grow them in groups of at least three.
Begonias grow happily in light shade or sun, provided the soil is enriched with humus. Water them regularly during dry weather — erratic watering will cause the flowers to fall off. Give begonias in containers a dilute liquid foliar feed every week until the last flowers fade.
Lift the tubers before the first frosts. Dry the plants off thoroughly, remove the stems and clean any soil off the tubers. Store them in boxes of dry compost in a frost-free place over winter. Water lightly now and then to prevent the tubers shrivelling.
Intake 7.5-10cm (3-4in) basal cuttings, preferably with a heel of the parent attached. Root the cuttings in a proprietary cuttings compost in a propagating case at 18-20°C (64-70°F). When the cuttings have rooted, pot them up in compost for planting out in early summer. Alternatively, divide the tubers in mid spring when the shoots are small.
Pests and diseases
Weevils can be a problem tunnelling into the begonia tubers.