Tuberous Begonias

Tuberous begonias flower from June until the first frost in red, orange, yellow, pink and white, and are among the few summer-flowering plants that bloom generously in partial shade. Start the tubers indoors from March or plant them straight outdoors after the Ice Saints (mid-May).

Buy begonias: tuberous begonias for shade and partial shade

Tuberous begonias (Begonia × tuberhybrida) are grouped by flower form and habit. Large-flowered double varieties bear rose-like flowers and suit pots and borders. Trailing varieties, often sold as Pendula or cascading begonias, grow with a trailing habit and are ideal for hanging baskets and window boxes. There are also varieties with frilled flowers or flowers with contrasting edges. All forms have the typical lopsided leaf that gave the genus its German name, Schiefblatt.

Planting time and position in Switzerland

Tuberous begonias are not hardy and do not tolerate frost. For early flowers, place the tubers in pots of seed compost from mid-March and keep them in a bright spot at around 18 degrees. The plants go outdoors on the Swiss Plateau after the Ice Saints in mid-May, at higher altitudes only at the end of May or early June. Planted straight into the border, they start flowering a little later. A partially shaded spot with morning or evening sun is ideal; strong midday sun scorches the leaves, and in deep shade they flower more sparsely. The soil should be humus-rich, loose and evenly moist.

Planting and care

The tuber has a rounded side and a hollow side. Place it hollow side up, only 2 to 5 centimetres deep, so that it is just covered with soil. A spacing of around 20 to 30 centimetres is enough in the border, a little less in window boxes. Water regularly but avoid waterlogging, and water onto the soil rather than over the leaves where possible to prevent mildew. From June to August, a liquid feed every two weeks encourages flowering. Remove faded flowers regularly.

Overwintering

After the first light frost, or by October at the latest, bring the tubers in. Let the foliage die back, remove soil and stem remains and store the tubers dry, dark and frost-free at about 5 to 10 degrees, for example in peat or newspaper. Next spring you can start them into growth again; healthy tubers flower for many years.

Uses

Tuberous begonias go well with hostas, ferns and fuchsias in shady corners of the garden or on north-facing balconies. Trailing varieties look good in hanging baskets, upright varieties in bowls and as border edging.