Ask John Negus
John has been answering reader queries for 50 years
What is the key to begonia success?
Q How can I successfully start and grow begonias? I never seem to have any luck.
Chris Williams, Devizes, Wilshire
A The best time to start begonia tubers is in spring – March or April. Start the tubers off by potting them into the smallest containers possible using peat-free multipurpose compost and begin watering.
The tubers should be placed hollow side up, and not fully buried in compost, though some people say burying them in a thin layer of compost encourages more roots to develop all over the tubers. The choice is yours!
Keep the pots at 16-21ºC (60-70ºF) – a bright warm room is ideal.
When the new shoots are a couple of inches high, pot up the tubers into suitably-sized containers and continue to grow them. Reduce the temperature slightly to encourage the plants to start the process of hardening off.
If you start your tubers well into April you won’t need to have them indoors for so long before starting the hardening off process in earnest, and this potting could be into their final containers.
If you plan to plant them directly into the soil you may need to pot
