Make sure that you make the most of the frost-free growing season. Sow your seeds in single pots in May in a greenhouse or on a sunny windowsill. When the roots fill the pots, and the second set of leaves have appeared, harden off your plants over several days. Then plant them out in rows and encourage them up their canes (climbing varieties). Always make sure your cane supports are strong enough and are very firmly in the ground. At maturity, both weight and wind resistance can be high. Labelling is important. Label the canes with the bean variety.
If you intend to leave all to go to seed, a tepee set-up is fine. If you intend to pick some beans at the green stage, and leave some for seed, it is better to plant in a row. This way you can see which whole bean plants you want to leave for seed. Most people leave just one (or preferably two) plants at the end of each row. Remember not to pick any pods at all from these plants. Keep picking pods often from the other plants to encourage more and more beans to come. Dwarf beans getting heavy with pods will need to be tied to short stakes.

Harvesting seed

Harvest on a dry day, or if possible, after a few dry days. You will probably start with harvesting a few that are ready, and leave some till the following week, and so on. Harvesting seed is likely to be in September and into October, depending on where you live. It is important that the bean pods are completely dry and brittle and they have usually turned a pale brown. You may be able to shake them and hear that the seeds inside are dry and even detached from the pods. Snip the pod stalks with scissors to detach them from the vine. Bring the pods indoors and shell out the bean seeds. Spread them out on plates and leave on a windowsill, but out of direct sunlight, for a few weeks to dry off still further. Label the bean varieties on the plates. With experience you will be able to tell when they are really dry. They shrink slightly and they ‘tinkle’ if lifted off the plate and dropped back down again ! (Beans that are not dry give a ‘thud’ !)

Storage

Storage is important. Store your seeds in brown paper envelopes. Label the envelopes. The envelopes can then go in a plastic box with a lid. This is to stop moisture (and mice !) getting in. The box should then be stored in a dry and cool (but not frosty) place. A cold dry garage would be a good place. If you intend to eat some of your bean seeds in winter casseroles, these ones can be stored in a jar in a cool cupboard.
All the above notes can be adapted for Runner Beans. Broad (Fava)Beans and Peas will be grown earlier and will therefore be ready for seed-collecting earlier. Sowing and harvesting at the right times, and correct storage, will ensure your seeds will be viable for at least the next two years.

More Notes on Seed-saving

Give a minimum of 10m isolation (separation) distance between different Climbing Bean varieties to ensure that they do not cross-pollinate with each other. Dwarf Beans grown for dry bean seed (winter use) production can be planted a bit closer than this without crossing. Peas tend to self-pollinate so you can expect your pea seed to stay pure. Runner Beans tend to cross with neighbours’ Runner Beans (they may not be growing the same variety as you !). Broad (Fava) Beans likewise are harder to keep pure.