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.
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. 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.