No. 8
FRENCH BEANS
Phaseolus vulgaris
Family: Leguminosae
French bean seed saving guidelines also available as a PDF document (229Kb)
French beans are either dwarf or climbing (bush or pole in the U.S.), but many dwarf varieties put out a few long, climbing shoots. Different varieties have been selected to be eaten at different stages; immature pods of snap or green beans, fresh swollen seeds (often called haricots) removed from their pods, and dried mature beans. Some are stringy, others stringless. The colour of the pods varies from yellow through to green and purple, and some are beautifully marked. The bean seeds themselves come in a bewildering array of shapes, sizes, colours and patterns.
The flowers are perfect, self-compatible and predominantly self-pollinating.
Growing and Roguing
Dwarf French beans
drying
- French beans being grown for seed should be grown as you would for an edible crop. However, you should give them as long a growing season as possible to allow the pods to mature and dry.
- As French beans are inbreeders (that is, they self-pollinate), you can save seed from just a few plants. It is better, though, if you grow as many plants as possible as you may need to rogue and select. We recommend around 20 plants.
- Some plants may produce noticeably different foliage or pods from the majority of the plants; seed should not be saved from these.
- Like peas and runner beans, the characteristics of the seed — its size, shape, colour and markings — should be more or less uniform and the same from generation to generation. There will be no visible signs of crossing until the second generation, so go back to the seeds saved from two harvests previously for seed that should be pure.
Pollination and Isolation
Insects rarely visit French beans and crossing between different varieties is not usually a problem. However, some cross-pollination can occur. It is good practice to isolate by several meters to be on the safe side, if possible.
Harvesting
French beans are easily harvested when dry. The pods should be dried on the vines but if bad weather threatens, uproot the plants and hang them upside down somewhere warm until the pods are completely dry.
Cleaning
Hand-podding beans
Cleaning refers to the removal of chaff and debris, leaving only seed. Cleaned seed keeps better.
It is best (if not dealing with large quantities) to pod French beans by hand. However, larger quantities can be threshed or winnowed. Threshing can be done by putting the pods into a pillowcase or sack or inside a plastic dustbin and shaking vigorously. Seeds threshed this way will need additional cleaning by winnowing.
Winnowing is best done outside in a stiff breeze. Pour the beans steadily from one container to another, allowing the wind to blow the chaff away. Repeat until the chaff is gone and you are left with only seed. Do this over a tarpaulin, in case a sudden gust upsets the container and spills the seed.
If necessary, set the beans out to dry further somewhere warm and dry, but don’t allow them to get too hot.
Bean Seed Beetle damage
You may notice small holes in the beans. These are caused by bean weevil, or bean seed beetle, larvae. These can devastate your crop of beans as they eat the endosperm away when they hatch. The beetles can eat through paper envelopes. If they start feeding on the seed embryo the bean will not germinate. Adults often emerge in storage and can complete several generations before planting time. Be sure to remove all trace of any beetles you may find. All life stages can be destroyed by a 7-day minimum stay in a fridge. Freezing a batch of dried, infested seed for 5 days in the freezer should kill the beetles but not the seeds.
Ensure beans dry out fully afterwards and before storing. Hand-podding allows any bad seeds, or seeds infested with bean seed beetle, to be identified and discarded. Shaking packets and covering seeds in a light oil can help guard against future damage. The beetle damage does not affect germination, so long as the embryo is not attacked, so you can keep the seed for home use (as long as they don’t still have the beetles in them) — but they do look unsightly.
Storage
French bean seed should last in cool, dry storage for at least three years.
Returning Seed to HSL
It is important that seed returned to HSL is not cross-pollinated. Do not send us seed that you suspect might have crossed.
Remove any beans with obvious bean weevil damage. Do not return them to HSL. Retain any that have not sustained damage to the embryo for your own use. If you have frozen the seed please note this on the packet.
Seed must be completely dry and fully cleaned. Seed that retains moisture can go mouldy in transit and will have to be discarded. It can take a few days to get to us in the post. Pack it in breathable material (e.g. a paper envelope or cotton bag) and place it in a padded envelope or stout box to protect the delicate seed from impact damage, before sending it in the post.
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