Pole beans need something to grow around and up. Which kind of stimuli can encourage this type of growth?

Pole beans can be encouraged to grow around and up by the stimuli of touch or mechanical support. When the plant comes in contact with a support structure, it triggers a response that causes the plant to grow upward and wrap around the support. This type of growth is known as thigmotropism. Therefore, providing a trellis, stake, or other support structure for the pole beans to climb on can encourage their upward growth.