RHS trials horticulturist Ian Tocher outlines his top tips for growing this traditional veg
Easy-to-grow and nutritious, French beans provide a plentiful crop throughout the summer. Supermarket-bought varieties are inevitably the green, pencil-shape French beans, but there are so many more interesting ones to choose from when growing your own. Depending on the variety, you can eat them fresh when young as whole pods, as fresh beans when half-ripe, known as flageolets, or matured and dried as haricot beans. The flowers are ornamental, too.
CHOOSING VARIETIES
There are two types of French bean: dwarf and climbing. Within these types, there are flat-podded, pencilshaped or curly beans with either green, yellow, purple or multi-coloured pods. Climbing varieties, known as pole beans, include ‘Algarve’ with stringless straight flat pods, yellow ‘Golden Gate’, and the gorgeous Italian variety ‘Borlotto Lingua di Fuoco’, with long green pods striped red. Dwarf beans include early cropping ‘Sonesta’ AGM with waxy bright yellow pods and ‘Purple Teepee’, with pretty magenta flowers and decorative purple pods (although these turn green when cooked).
GROWING REQUIREMENTS
Despite the name, French beans are originally from South America, so are not frost-hardy. They like a warm, sunny spot, with well-drained soil.
As legumes, French beans ‘fix’ nitrogen into the soil in their roots. Legumes are one group of vegetables rotated around the vegetable garden on a three- or fouryear cycle, which helps prevent the build-up of soil-borne pests and diseases. Brassicas are traditionally planted in the same ground after legumes, taking advantage of the nutritionally-rich soil.
To prepare the planting area, dig in some well-rotted organic matter or manure. This will add nutrients, aid moisture retention and improve the soil structure and drainage. Alternatively, create a bean trench approximately 90cm wide and 60cm deep, fork over at the base to aid drainage, add well-rotted organic matter and replace the soil.
SOWING AND SUPPORTS
Direct sow French beans outdoors between mid-May and mid-June. For crops through to the autumn, sow successionally at two-week intervals. Do not start bean seeds when it is cold and wet, as they will not get off to a great start. It is a good idea to pre-warm the soil by covering it with cloches for a month in advance.
Climbing beans will need supports. To avoid disturbing the plants once they are growing, it is good to erect the supports before seed sowing and this also means seed spacing is set up in advance. Use a double row
