Begonia seed is very small and great care has to be taken when sowing seed.
The first stage is to prepare the compost. Fill a seed tray three quarters full with a good quality seed compost. For the final third the seed compost should be passed through a fine riddle. The top of the compost should now be gently firmed and watered by immersion until the compost is visibly wet.
The seed needs both light and heat for successful germination and an electric propagator with the thermostat set at 75 degrees Farenheight is ideal for the purpose. a sheet of glass can be put over the seed tray to prevent it drying out but it must be wiped at regular intervals. After about 14 days the seed will germinate and can be grown on under lights until it is ready to prick out. If seedlings receive less than 14 hours daylight they will stop growing and start to produce tiny tubers.
Seedlings Ready To Prick Out
Seedling At Correct Stage For Transplanting
Seedlings should be pricked out into a good quality seed compost and kept in a warm humid environment to grow on.
Once plants are large enough gradually reduce temperature and grow on, they can either be boxed up for bedding out or potted on and treated the same as the named varietes. It is important that plants are well hardened off both to cold and light before planting out and up to three weeks in the cold frame can be required.
In scotland the ideal time to plant out is end of third week in June, to avoid the cold East winds that badly damage foliage.
Begonias Bedded In Garden
Seedlings grown in the greenhouse are grown on and treated like any other plant before dormancy.
Plants bedded out are left in the garden until they have been frosted. Most of the foliage is removed when lifting and the stem and rootball are dried off in the greenhouse. Tubers can then be treated and stored in the normal manner.