Growing runner beans for improved food security
By Beritah Mutune
Runner beans (Phaseolus Coccineus) commonly called the butter bean is a plant in the legume family, Fabaceae. Although it is traditionally grown in the highlands of Eastern Africa, it has received little research attention in the region including Kenya. If awareness is done on the nutritional and economic benefits of growing this plant, this can greatly help improve the nutritional and food security of most smallholder farmers in Kenya.
Why plant runner beans?
It is important for farmers to be aware of the benefits of planting the runner beans in their fields. Runner beans are highly valued as an export crop due to their good taste, richness in proteins, low carbohydrates, good fat content, magnesium and other micro-nutrients. Their yield potential is over 5 tons/ha, they fix nitrogen into the soil and have higher net benefit than bush beans.
Requirements for growing runner beans
- Attitudes and climate
Runner beans are known to do well in cold attitudes (1500 m above sea level ). Contrary to popular believe, growing of runner beans is easy in the tropics.
- Soil and soil fertility
Runner beans like most of the beans do well in warm (15ºC -25ºC), well drained, well ventilated and fertile soils. Compost or animal manure should be added to the soil before planting. Worth noting is that beans and other legumes don’t require nitrogen rich soils because they release nitrogen to the soil. Ideally organic fertilizers rich in phosphorous should be used to dress the soil before planting and during growth.
- Land preparation
Growing runner beans begins primarily as usual by cultivation where ploughing of the land is done to achieve a fine tilth. The soil should be dry to avoid formation of hardpans resulting from compaction when done on wet soil. The land is then left for a period of 3-4 weeks to solarize. This process exposes soil-borne pathogens to high solar temperatures.
Afterwards, the land is then harrowed to a fine tilt. It can be ‘decorated’ using a bed maker so as to level it hence achieving flat tops. The beds are raised 45 centimeters high running parallel to each other at a spacing of 60 centimeters.
- Planting and spacing
Once the soil is well prepared, the beans are planted directly to the soil at a depth of about two inches and 2 feet apart. Since runner beans are climbers, strong poles of 7 to 9 feet should be erected and joined across to form a Tee before planting to support the climbing plants. Other methods of support, like a fence or some form of a tent-like structure of support, can be used depending on the area where the beans are being grown. The plants do well in full sun and should not be shielded from the sun. Care should be taken to give enough space between plants to allow flowering and high yields. Runner beans are planted 6 inches apart and 1.5 meters between rows. The beans germinate 2 weeks after planting and they grow to a height of more than 3 meters but for the sake of picking the pods, it is coiled to grow downwards. It is advised that no other plants be planted in the same plot as runner beans since their big leaves would shield other plants from the sun.
Watering
Runner beans require enough water for them to grow well. Use of drip lines for supplying water should be laid on the raised beds in double rows spaced at 30-40 centimeters inter rows in times when they are planted off-season. Drip lines; 15cm interval discharge are suitable. Furrows should be made along the drip lines at a depth of 2mm. Mulching can be done to help conserve moisture.
Supporting runner beans
Runner beans as the name suggests are climbing vines and need to be supported. This should be done after the vines/stems appear during the vegetative stage. Knitting thread or manilla thread should be fastened on supporting posts in a crisscross manner. The vines then use the mesh to support themselves. Proper weeding and pest management is important to ensure that the they are not competing for nutrients or getting destroyed.
Harvesting runner beans
Runner bean farming usually takes 10-15 weeks within which the crop is ready for harvest. It is important to note that maturity of plants depends a lot on the climatic conditions e.g. temperature and water and therefore the farmer should be aware of how the crop would look like at maturity. The pods of the runner beans would be approximately 6 to7 inches when ready. Note that if not picked the plant stops flowering.
Pests and diseases which affect runner beans
The most common pests and diseases on runner beans include blight, slugs and aphids. Some diseases such as blight are usually as a result of poor seed selection. Aphids can be controlled and managed by pouring a lot of water on the plants preferably using pipes.