Advice from Gransnetters about Begonia

If it is a foliage Begonia grown as a house plant, then there is no need to throw it away if it flowers. With care, it should live for years, but it's not suitable for planting in the garden! Most foliage begonias come from tropical climates, and usually grow from rhizomes (creeping ground stems). Garden Begonias are usually grown as annual bedding plants, or the tuberous Begonias grown in hanging baskets.

I have had two tree flowering for years. It will die away to nothing in the winter so make sure it has a label. Keep it dry over winter (indoors) and start to water and feed it in the spring.

Shouldn’t they go into the greenhouse over Winter though?
You could try that?
Most houseplants are exactly that though I have put out in pots, various plants ( from the house) to spend Summer outside ( a little holiday for them) but I return them to the house in September.