Overwintering Begonias

[stewamax]

I have dug up my tuberous Begonias - the earthy tubers plus a very short piece of stalk - to be stored in a cool place indoors.
Q: Should the tubers be washed of earth or left as is ?

[Breelander]

I have dug up my tuberous Begonias - the earthy tubers plus a very short piece of stalk - to be stored in a cool place indoors.
Q: Should the tubers be washed of earth or left as is ?

Neither, they should be stored in barely moist soil or sand.

Tuberous begonias need to be lifted before the first frosts. The leaves will begin to yellow naturally at which time watering should be reduced. The dry tubers should be stored in barely moist soil or sand in a frost-free shed, ideally at 7°C (45°F), and watered occasionally to prevent shrivelling

https://www.rhs.org.uk/plants/begonias/outdoors

[Nimrod103]

In my experience, it is worth gently scraping the compost away to look for over wintering vine weevil larvae, which burrow into the underside of the corm.