Best Way to Grow Runner Beans
This may seem an unusual choice for container growing- even indoors the plants grow very tall — but runner beans are rightly a gardeners’ favourite. The taste and texture of freshly-gathered young beans is unmatched by that of commercially-grown produce.
R unner bean plants in flower in the open garden are one of the most attractive sights of summer. In the indoor garden, they can certainly be counted among the most decorative of the vegetable plants, but you must be able to provide at least 6ft (1.8m) growing height to obtain a useful crop, and you will need to train the plants on long canes. The plants also need large containers, and for your own benefit the pots should not be grouped too closely – runner bean plants climb and cling to anything within range, and you could end up with an unmanageable tangle if they are allowed to intertwine with each other. If you see this happening, cut the crossing tendrils before they become inextricably engaged.
Despite this, runner beans are a highly worthwhile crop if you can provide the right conditions. They produce a generous crop for the space they occupy, and the beans are beautifully tender and well flavoured if picked while still developing: they become coarser with age. In commercial growing, economics dictate mass harvests, which preclude selecting young beans at the perfect stage, so the quality of market vegetables can vary widely.
Selecting runner beans for indoor growing
Few runner bean plants will crop as well indoors as they do in the open garden, so you should choose the most prolific varieties to obtain the maximum potential. Streamline is a cultivar producing slender pods up to 20in (50cm) long which I have found satisfactory for container growing. In the garden, Goliath is the perfect variety, highly productive with large, succulent pods, but allow for the fact that it will not do quite so well indoors. One with shorter pods – average 12in (30cm) in length – but an equally good cropper, is Scarlet Emperor. All three bear attractive scarlet flowers.
Dwarf cultivars are available which can be grown in limited space, but the crop is naturally smaller in the size of the beans and the overall harvest. It is preferable to plant those of the larger varieties which can accustom themselves to containers.
Sowing and germination
There are no specialrequirements for growing runner beans. A good soil-based potting medium is suitable, though you can add some peat or humus if preferred, and a little sand to improve drainage. Runner beans can be started in early spring indoors. Sow two seeds to a 3in (8cm) pot. Make hole in the soil 2in (5cm) deep and implant the seed upright, then fill the hole. The growing medium should be moist but not wet, and a moderate temperature is adequate – being basically garden varieties, these beans do not need excessive heat.
When thecome up, remove the weaker of the two and allow the stronger one to grow on until it is time to transplant. If there seems little difference in quality, transfer one to a separate pot and grow on both plants. As they outgrow the small pots, pot them on into a one-size larger container. It is advisable to avoid root disturbance as much as possible, so the plants should only be transferred one more time after this, to the large pots or tubs in which they can mature and produce the crop.
Training and support
Once the plants are in their final containers, support them with canes and as the plants increase in size, provide the 6ft (1.8m) canes on which they can climb freely. These can be inserted in the growing medium immediately at the same time that the plants are finally potted on, if the containers can be placed in their permanent site at this point. Water generously and make sure the water drains through the containers so there is no waterlogging of the soil. It is necessary to stand the pots or tubs in large trays to collect the excess water. Leaves wilt rapidly if the soil is insufficiently moist and in summer daily watering is required -twice daily in extremely hot weather.
When the plants have reached the top of the canes, pinch out the growing points. This has the effect of causing the plants to produce side shoots, and it is these which bear the flowers and subsequently the beanpods. Without pinching out, the plant will continue to produce leafy growth.
As soon as the flower buds form, start to water in diluted liquid fertilizer once a week. As the flowers open, spray with tepid water over several days to disperse pollen. A prolific plant produces flower buds over an extended period, so it is important to keep up the spraying to ensure that all the flowers are pollinated.
Continue watering regularly as the beans develop – runner beans are thirsty plants and lack of moisture inhibits the crop. Start to pick beans as soon as they are of a good size for cooking. Check the plants every day and harvest in batches while the beans are still tender and smooth. If you leave them too long, the pods become coarse and stringy.