Beans

Most amateur veg-gardeners grow beans of some sort. In the UK, Runner beans (Phaseolus coccineus) are very popular and can be seen in their thousands in gardens and allotment sites all over the country, but I think other types of beans are becoming much more common these days, perhaps because they appeal to people who think Runners are old-fashioned and boring. My wife and I love Runner beans, so I always grow some of those, but I usually augment them with one or two other types, just for variety. Last year, for instance, I grew "Cherokee Trail of Tears", and "Tunny" beans.  This time I have Borlotti "Firetongue" and "Kew Blue" climbing French beans.

Bean plants - especially the French type, Phaseolus vulgaris - are quite frost-tender, and are therefore not usually planted or sown outside until the danger of frost has passed. This is why my "Kew Blue" ones are only just germinating:

So that you can get them in the ground a bit earlier, it is a good idea to sow the seeds in pots, which can be kept inside or in a coldframe or greenhouse until the weather is suitable.

I expect many readers don't need much advice about how to grow beans, so today I'm just going to offer a few nuggets of miscellaneous information about beans, perhaps things that you didn't know or hadn't previously thought about.

For instance, did you know that it is easy to tell the difference between young Runner and French bean plants by observing whether they have visible cotyledons or not. [The cotyledon is the seed-leaf part, from which the bean plant's shoot emerges]. Runner beans leave their cotyledons underground and you therefore seldom see them, whereas French beans emerge with their cotyledons held up high.

These "Kew Blue" beans are French beans, and you can clearly see the cotyledons pushing up through the soil before releasing the shoot with its first pair of true leaves:-

These are Runner beans, so no cotyledons can be seen:-

Sometimes a bean plant comes up "blind" - in other words it's growing-point is absent, and it therefore won't develop properly and should be discarded. Here's an example:-

I can't explain the science behind it, but bean leaves can cleverly adapt their posture in reaction to sunlight and temperature. When the temperature is relatively warm, but not hot, the leaves lie horizontal in order to absorb heat from the sun, like this:-

When the sun gets too hot for comfort the leaves adopt an unright posture which exposes less of the surface to the sun's rays. This photo was taken in the early afternoon, and the bean leaves have folded up:-

When it is cooler, for instance at night-time, bean leaves often fold downwards, to conserve warmth, and they appear to be hunched up. I don't have a good photo of beans in this position; this is the best I can do:-

Another curious fact for you: Runner beans climb clockwise (when viewed from below), whereas almost all other beans climb anti-clockwise. Why? I don't think anyone knows!

My next "nugget" is the idea that pinching-out the growing tip of a climbing bean plant may be a good way of maximising its yield. The theory is that if you pinch out the main growing-point it diverts energy to the sideshoots, and you get two "pretty good" shoots instead of one very strong one, so this...

...becomes this:-

Personally, I'm not convinced by this. It may or may not work. My own observation is that if you have too many stems on a bean plant it may well get overcrowded, with too much foliage and end up producing a smaller yield than if you had just left it to grow naturally.

Does anyone else have any interesting facts about beans that they could tell us?