Borlotti Beans are such a great crop, and if harvested and stored in a certain way you will be able to keep them for several months, ready to bung in stews and casseroles throughout the autumn and winter months!
As long as it remains reasonably warm and dry (this last blast of great weather is perfect) then let the beans keep on growing until the pods dry out on the stalk. The beans inside the pods will swell (you’ll see the pods getting plumper) and eventually the pods will start to shrivel up, turn deep purple and then brown as the foliage begins to die back. Once they’ve dried out you’ll be able to hear them rattling around when you shake a pod. This is the best time to pick them.
If the weather forecast changes and a prolonged wet spell comes in, it’s sensible to pick any mature pods (those that are swollen) and dry them under cover instead. This will prevent them from rotting and going mouldy. We find laying them all out in a fruit crate in a sunny porch or greenhouse is great for drying them out.
Once the beans are fully dry put them into an airtight container. It’s really important that they are completely dry before you store them, otherwise they’ll just go mouldy. You’ll know the beans are dry enough when you are unable to make an indentation in the beans with your thumbnail – they will be totally hard. They should keep in the airtight container for up to a year, perhaps longer.
You can also let French beans dry out in this way to collect and store the beans over winter.