I thought some of you might find this interesting. I'm growing Kentucky Wonder pole beans in a spot just outside one of my kitchen windows. It's been fun watching them grow, and noting that they put on about 4-6" of new growth every night.

Two of the vines have grown about 8" beyond the top of the support I provided for them. Over the past two days I watched the vines move in various directionsÂfacing each other, facing away from each other, etc. I wanted to find out why and how they did this. So I wrote to a Ph.D. bean research scientist, and this was his reply:

Susan, The twining habit in climbing beans is controlled by the

Tor gene (Latin torquere) first described in 1915. It confers the light

controlled phytochrome climbing habit in climbing beans and is absent in

bush beans (recessive tor gene). Ancestral primitive beans were largely

climbers and used this trait to climb over vegetation to seek light. So the

two plants in your case are not reaching for each other but they are twining

around (have a rotational motion that has been demonstrated with time lapse

photography). If they did touch they would vine together and might climb

upwards more as they support each other. Since the vines do not have support

(8" above the stakes) gravity will take over and cause them to fall

earthward and this action is a kind of free fall - without direction. If

they detect support again they will continue to climb upwards toward the

light. I have see vigorous climbers in wild climb over all types of

vegetation. In your case the vines are not seeking each other but as they

continue to grow they will rotate in search of support driven by light. When

we work with climbing beans in the greenhouse (rarely in the field) we turn

the vine down on the plant itself otherwise they would seek the greenhouse

supports, flower and set pods were we would not be able to harvest them. I

hope my few comments are of interest - have a good harvest!