These plants are usually from tropical or subtropical regions so are highly vulnerable to frost. Seeds need warm soils to germinate. Most annuals are categorised as tender (e.g. marigolds).
Annual, Tender
Posted in: Gardening Glossary
Fantastic! Planted only three (I have a small container garden), but all three produced quite a lot of beans, more than I was expecting. I did find that they liked something to help prop them up, though (I used a wire tomato cage flipped upside down). Otherwise, when the beans started getting big, they'd lean too far over.