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Runner beans do not grow very well in the far north of scotland so this
year I decided to try growing them in the polytunnel. The plants are
growing very well, in fact I'm not sure whether I should pinch out the
tops to stop them over-growing. My main problem is that the flowers are
not setting any beans. How do I ensure pollination?

I find the earliest flowers rarely set. Possibly because they are
lower down on the poles and insects don't find them; or because they
flower before it's quite as warm as they'd like. My runner beans (in the
open) are very behind this cold year, only half way up the canes :-(.

Perhaps there aren't many insects in the tunnel? Keep a door open
during the day if wind permits, and pots or jamjars of marigolds might
help attract insects inside. If none of that works, the traditional
method of hand pollination is a rabbits tail tied on a cane dusted from
flower to flower. Remember you'll have to press the beanflowers' bottom
"lip" to reach the pollen and stamens.

Janet (Isle of Arran).