French and runner beans top the pole in our summer gardens, whether in allotments or patios. However tall you make the bean frame, the plants sway around at the top. I haven’t used ladders for harvesting the crop but have sometimes thought I should. So the plants will happily make a tall screen.

I always grow tall, not dwarf, varieties because the same amount of ground space gives you a much larger crop and it’s a good way to use vertical space.

Despite our cold spring this year, frost risk is unlikely now, so it’s perfectly safe to plant out if you haven’t already done so. Use two-metre poles for the climbing frame, arranging, in the open ground, in a traditional A-shape with two lines of plants merging at the top, or, in a planter close to a wall to support the poles. The plants become quite heavy by the end of the season so poles need to be firmly attached to each other or to a wall.

The poles should preferably be 1-2cm diameter, with a slightly rough surface because plants climb “natural” surfaces more readily. Wooden or bamboo poles with their slightly rough texture are easier for the growing shoots to grip. Although the shoots do have a slightly prickly surface, plastic poles are too slippy for easy climbing. Again, strings work but the tiny diameter means the beans quickly climb vertically rather than more gradually as they would with a broader support.

After planting, tender wee stems sway around seeking something to climb. We attach these tender shoots to the frame to prevent wind damage and must remember that French beans climb counter-clockwise, while runners go clockwise. Wrap them wrongly and the shoot will unravel.

So how do these beans circumnutate, sway around, to find their supports? As water from the soil is pumped up the plant, the outer cells on the stem’s epidermis, skin, swell and become turgid. Meanwhile inner cells, those nearest the pole, don’t swell and can very slightly contract. This process forces the stem tip to move clockwise or anti-clockwise round the support.

Beans are super productive and we inevitably miss some of our harvest, or have a larger crop than we need, but don’t worry. Leave any large and stringy pods to swell and produce beans for shelling at the end of the season. This will reduce the total harvest, but it looks as if you’ve more than you can handle anyway. Enjoy.

Plant of the week

Aquilegia alpina has brilliant blue flowers that truly reflect an alpine sky. Prominent, pollen-laden stamens and abundant nectar attract a range of bees.

The lacy blue green foliage is an asset in the border all summer. Plants only grow to a maximum of 60cm so place near the front in moist but not soggy soil in full sun or light shade. This aquilegia is native to Swiss alpine meadows, so very cold tolerant, but requires a fairly open situation.