Beans

 

difficulty rating: easy
suitable growing site: open ground or large pot - balcony, garden or allotment

days from sowing to harvesting: 50-90 days 
risk of cross-pollination: low
when to sow: sow bean seeds in april in pots containing seedling or multi-purpose compost. for later crops, sow seeds directly outside in late spring. plant out after last risk of frost.
requirements: good quality soil and regular watering. 
harvesting for eating: varies by variety.
harvesting for seed collection: towards the end of summer, when the beans become full and pod skins become thin and dry.

Here is a video of Vicky explaining how to look after broad beans and how to make sure they are properly prepared for seed saving. The same advice applies for other beans!