Um guia de cultivo passo a passo, da sementeira à colheita.
pH ideal 6.0 to 7.0Temperatura ideal 18 to 27 °CCompasso 10 to 15 cm in the row, 40 to 60 cm between rows
Sementeira
Always sow direct where it is to grow, three or four centimetres deep, with the soil already above 15 °C. Germination takes five to ten days. Sowing into cold wet soil rots the seed before it emerges, and that is the mistake that fails this crop most often. Do not soak the seed, despite what is often said: it swells and splits. Sow every three weeks until midsummer for a continuous supply. This is a dwarf variety and needs no support, which makes it practical in a small bed or a container. It concentrates its crop into a short window of two or three weeks, so successional sowings every three weeks are worth making for continuous picking.
Solo
It adapts to average soils as long as they are loose, free draining and not over rich in nitrogen, at a pH between 6.0 and 7.0. It fixes its own nitrogen and leaves the soil enriched for the next crop, which makes it an excellent rotation opener. It dislikes compacted or waterlogged ground.
Clima
It needs warmth, between 18 °C and 27 °C, and tolerates no frost at any stage. Above 32 °C the flowers drop without setting, which causes a gap in production at the height of an inland summer. Shelter it from strong wind, which breaks loaded plants. On the Portuguese coast the crop starts slowly because nights stay cool and morning fog keeps the leaves wet for hours, so pick the sunniest spot you have, shelter it from wind and space the plants generously so air moves through. Inland in Portugal and Spain heat rather than cold is the limiting factor: in weeks above 35 °C the plant stalls and light shade over midday pays for itself. In France outdoor growing is reliable from the centre southwards, while in northern France and in Germany a greenhouse, a polytunnel or a warm south facing wall makes the difference, and planting out should wait until after the mid May cold snap. Where summers are short, always choose the shorter cycle varieties and start them early in a heated tray. In Italy it is an easy crop: in the centre and south plant from April onwards and the only real care is light shade through the July and August heat; in the Po valley and the north wait for the late frosts to pass and pick the sunniest spot you have.
Fertilização
It fixes its own nitrogen through root nodule bacteria, so it should not be given nitrogen fertiliser. Add mature compost only if the soil is poor and, if needed, a little wood ash for potassium. Feeding nitrogen is the classic mistake with this crop: it produces huge plants with few pods.
Rega
Water moderately until flowering and then generously and regularly, because flowering and pod fill decide the crop. Always water at the base and in the morning: wet foliage is the doorway for anthracnose and bacterial blight. A straw mulch holds moisture without wetting the leaves.
Controlo de Infestantes
Hoe often and always shallowly, because the roots are short, near the surface and break easily. The best method is to prepare the bed two or three weeks in advance, let the first flush of weeds germinate, remove it and only then sow: that gives you a decisive head start. A thin layer of sieved compost between the rows greatly reduces later work.
Controlo de Pragas
Aphids gather on the soft shoots and the flowering tips and weaken the plant badly: cut off the affected tips and apply potassium soap at the end of the day. Slugs and snails devour newly emerged seedlings, which is the main cause of gaps in the row: protect with an ash barrier for the first two weeks. Birds pull up seeds and shoots and are dealt with using netting or a light fleece over the row until the plants are ten centimetres tall. Also watch for thrips and for grubs boring into the pods, and remove any damaged pods.
Doenças
Anthracnose and bacterial blight make dark sunken spots on pods and leaves in damp weather, and spread by water and contact: never work among the plants while the foliage is wet. Powdery mildew covers the leaves with a white bloom late in the cycle. Rust forms orange pustules on the underside. Root rot appears in cold waterlogged soil, above all after sowing too early. Sow with generous spacing, water at the base and rotate on a three to four year cycle away from other legumes.
Colheita
For green beans, pick young and every other day, when the pod snaps cleanly and the seeds are still barely visible. Letting pods swell makes the plant stop producing, and that is where most of the crop is lost. Hold the stem with one hand and pull the pod with the other, so you do not break the plant. For dry beans, let the pods dry fully on the plant and thresh in dry weather. The reference colour is green and red, and that is what tells you it is ready.
