Lift, shake off surplus soil and allow to dry a while. Cut off the stems. When everything is dry place the corms on a tray of dry sand, peat , compost etc and half cover. Keep dry and frost free ( and out of reach of mice) until ready to bring into growth. Start regrowth in good time as they can be very slow to get going.

Thanks for asking this question Douggie!

Steragram, by half cover do you mean with the sand/compost or by putting something over the tray? :)

I just sit the corms on top of sandy-compost then cover the top of the pot with a tray. It is to keep mice off from eating them in sheds and garages etc.

I meant half bury the corms. My nice new shed has so far been mouseproof, so no need for a lid on mine! things were not this way in the old shed...The only problem with putting a cover on might be that if the corm was still a bit moist you might get some condensation and mould.

This only works if they are the right type of Begonias. It doesn't work on the fibrous rooted type.