Save your own seeds - broad, French and runner beans

Broad Beans

Broad beans will cross pollinate with other broad bean varieties nearby, so if you want to keep your variety pure you will need to isolate your plants.  But if you are unconcerned about some cross pollination then save seeds from plants in the middle of your bean patch.  Always save seeds from strong and healthy plants. Let your broad bean seed mature and dry on the bush.  The pods will turn dark brown, dry and wrinkled.  Then pick and shell them.  Check that they are really dry, and if they are not, dry them further in the sun in a good flow of air.  Broad bean seeds should keep for two years but if you want fresh seed grow plants for seed every year.

French and Runner Beans

It is important to grow some bean plants specifically for seed, rather than simply collecting the left-over pods at the end of the season.  The plants should be good strong specimens and any that are less healthy looking or not true to type for the variety should not be used for seed productions.

French beans are self-pollinating but if you are just saving seed for your own use, grow your seed crop of french beans at least 2 meters away from any other variety (4 metres if possible) and you are unlikely to have a significant problem with cross pollination. Runner bean flowers need to be 'tripped' by wind or insects before the beans set, and are much more likely to cross with other varieties grown nearby than French beans.

To collect the seeds, allow the pods to mature fully on the plan until they start to yellow and dry out.  Then spread out somewhere in the sun with a good airflow until the pods are fully dry and brittle. Once they are dry, shell out the beans and dry further out of the pods.  Store in an airtight container.  If they are well dried and stored in a cool dark place, the beans will last around 2 years. 

If you have problems with weevils eating your seeds, put the sealed container in the freezer for a week immediately after drying the beans, this will kill any insect eggs before they hatch.  When you take them out, let the container come up to room temperature before opening it, otherwise the beans will absorb moisture from the air.