Thursday, 25 June 2015

Runner Beans - more intelligent than you might think

Many plants have a remarkable ability to adapt to trauma and adverse conditions. Today I want to demonstrate this in respect of the Runner Bean.

Normally a Runner Bean produces one stem which is the clear "leader" - like this:-

In the axil between the main stem and each leaf a small shoot grows, but it normally remains insignificant unless the main shoot is pinched-out or damaged. In fact some growers advocate deliberately pinching-out the growing-point in order to stimulate the production of side-shoots. I generally only pinch-out my Runners when the stem reaches the top of the cane.

Sometimes the leading shoot runs into trouble, like this one. It has just stopped growing for some reason (pest-related, maybe). It has gone brown and is beginning to shrivel.

However, when this happens, the plant responds by switching its energy to the secondary shoots, ones which would normally remain insignificant. It's the same principle as cutting the main head of a Broccoli plant to stimulate the formation of side-shoots. That's what has happened here. The two shoots next to the bottom pair of leaves have put on a burst of growth.

In this next shot you can see the original main shoot wrapped round the cane at the right, whilst a second one is racing to catch up, and thrusting out strongly towards the cane.

This particular plant won't win the race to the top of the canes, but it may very well turn out to be the most productive plant of the batch.


  1. It will be interesting to hear how that plant does next to the other, unpinched out ones. I only pinch mine out when they get to the top of the cane too.

  2. I keep thinking I should pinch my beans this year. As so many of them died and I didn't have replacements. But I figure I'll just do it as normal, just like you do, when they hit the top.

  3. Like Jo, I'm wondering if the pinched plant will be more productive - if you get 2 or 3 runners when you pinch off the leader, will that mean you get a bigger harvest per plant? That would make an for an interesting experiment.

  4. I just ours - at least some as some have disappeared completely- have developed a strategy for overcoming slug attack.

  5. Really interesting point Mark! Thanks for sharing this.. In the past, the deer have (ahem) pinched back my pole beans for me and production was delayed by a week or so, but overall, the plants did thicken up and production increased.. Can't wait to see your updates on this. Niki

  6. I'm new to pole beans altogether so thanks for the useful info as I'm growing some this year.


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