First year of planting begonias

We bought a big batch of begonia tubers about six years ago and they have provided us with spectacular shows over the years - my husband takes them up in the autumn, dries them off and then they live in the garage overwinter in a cardboard box. However, with the last two very cold winters we have lost quite a few. We start them off in the conservatory around about Easter and then when they have a few leaves transfer them to the greenhouse before putting them out in tubs at the end of May/beginning of June (we live in Northumberland so have to wait until the chance of frosts has passed). The first few flowers are appearing now.

One of my neighbours always has a glorious multi-coloured display of begonias in front of his house, and there they are, right on cue, but he has a greenhouse. I have a small plastic one where I tried to encourage them before potting up, but they are just beginning to show foliage. Usually I can manage a nice trough of them but this year, though everything else is extremely fecund, the begonias are reluctant to flower.

Having any luck? I have planted one tuber in a pot but since i put it outside it is just sulking. Ditto dahlias. Ditto black eyed susans. I think all of these things come originally from warm countries don't they and need it to be nearer twenty degrees before they will do their stuff.

I have just got my first greenhouse, its only taken me 33 years, I would like to try growing begonias next year, it has been hot and dry here, the roses on my arch are already in full flower !