You don't say what sort of begonias you have Guest. Fibrous rooted ones are usually no trouble. Like all plants they need adequate feed and water and soil around their roots to thrive. The begonias with the large corms are very greedy as they develope so rapidly. They take up water so rapidly if in a container that they need more than one lot of watering a day. The containers get solid with their roots, so may need topping up with more soil. In shallow baskets they get very needy for water/feed. Sometimes I can't believe that so much plant can spring from one small brown corm. They like full sunshine too.