Grow Begonias from Tubers

A combination of beautiful double-flowers and textured foliage make the tuberous-rooted begonias attractive plants to grow.

There are also some very charming single-flowered varieties. The plants which are half-hardy, make colourful summer bedding and excellent pot plants in the greenhouse or on the patio.

Begonias also make gorgeous cut flowers which can be placed or floated in shallow bowls. Sea shells, for example, make attractive containers for this purpose.

Late winter and spring a wide selection of Begonia varieties and gardening materials can be ordered from here UK in the UK.

To obtain the earliest flowers, start the tubers off by sprouting them in a seed tray or box of damp moist John Innes compost No. 1 or general purpose potting compost, in February or March. Space them 2in (5 cm) apart and bury them in the potting compost so that the top side is just covered with a surface layer of peat.

The top side of the tuber can be identified as it is concave, whereas the bottom is convex. Even so, it is not always immediately obvious, so look for the scar left by the previous year's stem which is on the top side. You may also notice the new minute buds by the side of the scars, which will give this year's plant growth.
 

The ideal temperature to start the begonias off at is 18 °C (64 °F) but they do not seem to mind a higher temperature if placed in a seed propagator at 21 °C (70 °F) or if placed in the airing cupboard. However a temperature lower than 18 °C will mean a slower start.

When the tubers have sprouted and small leaves are showing, pot the tubers up to a 5 in (13 cm) pot filled with John Innes compost No. 2.

It is a good idea at this stage to place a supporting cane in the pot in order to tie the stems to it as the plant grows, because begonia's stem and foliage tend to be very brittle.

Later in the year, if the plant out grows its new pot, transplant it into a 7 in (18 cm) one and finally, if it is a very vigorous plant, into a 9 in (23 cm) pot with John Innes No. 2 or multi purpose compost.

If the plants are being grown for summer bedding start acclimatising them to the outside temperature and atmosphere in stages. This hardening-off process should start towards the end of May. For the first week of this process, put the plants out during the day in a sheltered postion such as the patio, and take them in at night.

After the first week, if the weather is not exceptionally cold and frost is not threatened, leave the plants out all night or put them into a cold frames. After the second week, if all danger of frost is gone, plant the plants outside. In the South of England this is usually the end of May and in the North, the beginning of June.

Begonias do not like a position that is too dry as this will cause the buds to drop. So a moist, partially-shaded position is ideal, especially if it is shaded from the mid-day sun. If exposed to the sun most of the day, water the plants frequently to prevent bud drop and keep the flowers blooming.

As the plants grow and buds form, start giving the plants a regular liquid feed that is high in potash such as a rose, tomato or seaweed fertiliser every ten days. This will promote good growth and an abundance of flowers, if maintained.

The begonia is like a 'peacock' as the male flowers produce the colourful double blooms, whereas the female flowers only form single blooms. The single blooms can be pinched out if you want to encourage the growth of the double one, especially for bedding or for show plants.

Towards the end of the year, when begonia leaves start to yellow, usually about October, reduce and stop all watering and feeding to allow the pots to dry out. When the pots are dry, empty them and save the tubers. Store the tubers in a dry position preferably in dry sand in a frost-free place for the winter season to grow again next year.

Bedding plants can also be saved by bringing them into the greenhouse before frost occurs. and allowing the foilage to die down. The tubers can then be stored in a frost-free place as above.