Storing and rejuvenating Begonias

A bit late for this year, but can anyone provide me with the definitive answer on how to store Begonia tubers over the winter and how/when to bring them back to life.  I have kept tubers for a couple of years now, with some success but not much!  So, to store in compost (dry? wet?) or in nothing at all?  In the dark/light?  In a greenhouse or shed?  Warm or cold?  And in the spring/early summer, once the first stirrings of new buds can be seen, do I pot them up immediately?  Water them and leave them for a while?  Take them into the light and do nothing for a bit?  At what stage do I put them into compost/pots/planting positions and with no help from a heated greenhouse or any other encouragement, should I be looking to plant them out/pot them up before June in any case? 

So many questions but this is a topic I feel very unsure about (as you can tell).  It has reared its ugly head because I took delivery of some Begonias in full flower from a nursery about four weeks ago and this seemed very early, particularly as my pathetic, overwintered specimens are still struggling to show any signs of life at all .....

Thanks GG - I didn't realise they should be kept indoors during the winter so I have been keeping them in the (unheated) greenhouse or in the garage (cos I didn't know whether they needed light or dark). Your info is really helpful so I will do exactly as you advise come the autumn 

I have some corms that are five years old now and massive beasts they are too 

As soon as our first frosts arrive, I dig them up and leave them on the (frost free in winter) greenhouse staging in large empty pot saucers until the leaves begin to wilt. I then cut off all the stems and leaves, turn the corms upside down and leave them in these trays under the staging until Christmas, when I turn them back over.

About the middle of February there are tiny reddish green buds form on the top, so I surround the corms with MP compost, that is just damp, until these start to grow, when I give the compost a little more water, but never to make it wet --- no holes in the saucers, remember!

They carry on growing, with the occasional foliar feed spray, until I harden then off and plant outside after the risk of frosts ie about now.   They go in containers, and the top of the corm is only just below the surface of the compost.

I hope this helps 

Just give thema very gentle squeeze - if they feel soft, then throw them; if not, give them another chance, though I would have thought by now they should have shown some signs of life.