In gardens French beans are the most commonly grown form of the species Phaseolus I’ltlgciris which is native to Central America. They are, highly susceptible to frost, grown for the production of edible pods borne on either dwarf, bushy, determinate plants or climbing indeterminate plants. This species of bean may also be grown for its , which when harvested immature are known as flageolets, or in the case of certain cultivars, harvested fully ripened, when they are known as haricot beans.
Dwarf French beans are the earliest maturing type and the plants reach a height of between 20-45cm (8-20in). Climbing French beans require support and may reach a height of 3m (I0ft). They are the more heavily yielding of the two types.
Pods may be either round in cross section or flat, according to cultivar. There is variety in straightness and crookedness, and in skin colour, which may be green, purple-flecked, purple or yellow. Yellow-skinned cultivars are referred to as wax pods on account of their waxy texture.
French beans have two considerable advantages over runner beans – they crop earlier and are far less prone to setting problems as they are self-pollinating.
Site and soil preparation Choose a site that wasn’t used for beans the previous year. French beans are vulnerable to wind damage so a sheltered site in a sunnyis best. Most soils are suitable but the ideal is a fertile, light, well-drained soil.
The autumn before, deep dig the plot and add a liberal dressing of well-rotted manure or . Work in a dressing of lime if the soil is acid. A couple of weeks before sowing, apply a general fertilizer at the rare of 85g per sq m (3oz per sq yd) and rake to a fine texture.
Sowing and planting Cold, wet soils often prevent the seeds from germinating. French beans require a soil temperature around 12°C (53°F) to germinate. This can be advanced by covering the site with cloches or film plastic for several weeks prior to sowing. Time can be gained by the use of the supports in first – crossed sticks or wigwams are suitable.
Since French beans are extremely frost tender, don’tseeds outdoors until a week or so after all risk of frost has passed.
Sow in drills 5cm (2in) deep, aiming at final distances similar to pot- or strip-raised plants, either raised at home under glass or bought. Transplant them into the prepared bed at intervals of 23cm (9in) in rows 45cm (I Sin) apart, or in staggered double rows, planted 23cm (9in) apart. If they are climbing beans, put those for transplants.
Sow another batch of seeds three weeks later to provide a succession of beans. If there’s room, you can continue sowing in batches outdoors until the cm] of early summer, for picking in early autumn or before the frosts. .Extend picking by a few weeks by covering the young plants with cloches in the middle of early autumn.
Looking after the crop
When the plants are I Ocm (4in) high, thin as necessary to 23cm (9in) apart, leaving the strongest. In early summer, mulch around the. Water often during the flowering period to help the pods develop fully over a longer period.
French beans start to crop within eight weeks of sowing and many produce pods for up to eight weeks between early summer and mid autumn. The more they are picked the more they produce.
Look over the plants every couple of days for young tender beans. Pick when the pods are I Ocm (4in) long – if they are left too long the pods become stringy and the plants stop producing.
When picking, hold thewith one hand and pull the pods downwards with the other. Alternatively, use scissors.
To dry haricot beans, leave the pods on the plants until they have ripened and turned white – in early to mid autumn. On a dry day, pull up the plants whole and hang them in a dry, airy place.
When the pods are brittle, shell the beans and spread them out on sheets of paper to dry thoroughly. Store in airtight jars.
What can go wrong
The main pests of French beans are beanfly, black bean and slugs and snails. Root rot can be troublesome, so rotate the crop to different sites around the garden each year. Anthracnose and haloblight are seed-borne diseases and are particularly troublesome in wet seasons.