How to Grow French beans

Phaseolus vulgaris

This plant, which originated in South America, has been grown in Britain since the mid-sixteenth century. This type of bean is most popular in France—hence its common name. It is sometimes known as kidney bean because of the shape of the seeds. There are dwarf forms, climbing forms and purple podded forms—all of which are grown for their edible pods which are usually sliced before cooking. Flageolet and haricot beans are grown for their seeds which are used either semi-dry or completely dry. Recently there has been a big increase in the area of French beans grown for quick-freezing. Plant breeders have produced cultivars which produce all the beans at the top of the plant, can be mechanically harvested and which remain stringless for long periods. A number of these new introductions are slowly becoming available to the amateur. French beans are half-hardy annuals which cannot be sown in the open until all danger of frost has passed.

Protected crops, which are grown in heated greenhouses or under cloches, will produce beans in May and June respectively whereas the first open-ground sowings will be ready in July. Successional sowings produce beans until well into the autumn.

Soil and fertilizer requirements

Light, well drained soils are required while it helps if organic manure/compost has been worked in during the autumn preparations. Acid soils will not be tolerated. Incorporate a good general base fertilizer dressing during the final preparations before sowing. 25 to 50g per m2 (1 to 2oz per sq yd) of something like fish and bone meal will be suitable provided that soft growth is not induced by too much nitrogen.

Seed sowing

If you have a greenhouse with a temperature of 15°C/60°F from February onwards a very early crop of French beans can be obtained. Sow 6 or 7 dwarf French bean seeds 4 to 5cm (1} to 2in) deep in a 22-cm (8-in) pot which contains a well-drained potting compost. If kept in the greenhouse these plants will produce beans by May. Outdoor sowings can begin with dwarf cultivars in mid-March. After sowing cover the rows with cloches or polythene tunnels until mid-May. Plants should be fully ventilated in warm weather.

Open-ground sowings of all types of French beans can be made from late April onwards with successional sowings at monthly intervals giving continuity of picking from July onwards. You can make further sowings of dwarf cultivars in mid to late July to produce beans at the end of the season in October. The onset of cold, wet autumnal conditions will kill off the plants but protection with cloches will allow picking to continue into November.

Seeds are sown in single rows which are spaced 45cm to 60cm (18 to 24m) apart for dwarf types and up to 90cm (3ft) apart for climbing and purple podded types. Sow seeds 8cm (3m) apart and 4 to 5cm (1-¼ to 2in) deep, but thin to 15cm (6in) apart in the rows after the first leaves emerge.

Crop management

Dwarf French beans need little attention during the growing season apart from weeding and pest and disease control. You will need to give supports to climbing and purple podded types, as they will reach 150 to 180cm (up to 6ft). Tall pea sticks, bamboo canes or strings may be used but take care to grow these taller types in sheltered areas as they are easily damaged by wind buffeting. Harvesting Pick the beans when they are young and tender. Any delay will tend to cause stringiness even though ‘stringless’ cultivars are now available. Regular picking will also encourage more pods to develop. Purple podded beans are also stringless and remain tender longer than other types. They lose the purple colour during cooking and compare well with other beans for flavour. The traditional French bean cultivars produce flat pods but cylindrical or ‘pencil’-podded cultivars are now available. The beans are in prime picking condition when the pods can be snapped cleanly. Yellow-podded or ‘wax-pod’ beans can also be grown. Again they are stringless and have a very delicate flavour. Only the seeds of flageolet and haricot beans are eaten—harvested soft and green in the case of flageolets and white or light brown in the case of haricots.

At the end of the crop remove the visible parts of the plants and dig in the roots to provide valuable nitrogen. It is safe to keep your own seed from French beans but you must be careful to choose healthy, true-to-type plants. The seeds must be carefully dried and ripened before they are stored.

Pests and diseases

Apart from the seemingly ever-present ‘Brittlewax’ is one of the best stringless, wax-pod beans aphids and the possibility of red spider mite attack (they produce yellow speckles on the leaves which then become bronzed and brittle), French and other types of bean may be attacked by the larvae of the bean seed fly. These legless larvae eat germinating seeds and are more likely to occur on heavily manured soils.

Grey mould (Botrytis) attacks any damaged tissues and you should be particularly watchful in wet seasons. The same conditions favour a seed-borne fungus which causes anthracnose of French, broad or runner beans. Sunken black spots develop on leaves, stems and, eventually, pods. The seeds ultimately become infected with a brownish/black discoloration. On no account save these seeds for next season’s crop.

Suitable cultivars

Dwarf French beans:

Most are suitable for freezing.

Green pods (flat-podded) ‘The Prince’: early; suitable for cloche work. ‘Masterpiece’: good yields over long periods (round or pencil podded.) ‘Sprite’: stringless, continental type. ‘Tcndergreen’: early but also long seasoned variety.

Yellow pods ‘Kinghorn Waxpod’: golden pods with white seeds.

Climbing French beans ‘Blue Lake’: very popular and high yielding. ‘Earliest of All’: green beans during summer, ripened as haricots in autumn.

Purple podded beans ‘Blue Coco’.

Haricot/Flageolet beans ‘Chevrier Vert’: general purpose. Used for green beans, flageolets or haricots. ‘Comtesse de Chambourd’: traditional haricot.

Use a frame or greenhouse until planting time in mid-May. You may still need to protect the plants so have cloches ready. Seed can be sown outside in mid-April on a site where the soil has been covered by cloches for about a month. Leave the cloches over the plants until they touch the glass when, for early beans, the tops should be pinched out.

Maincrop runner beans are sown outside from early May onwards depending on the district.

25. April 2013 by admin
Categories: Tips and Advice | Tags: , | Comments Off on How to Grow French beans

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