Runner Beans, Stalled

martinn123

Hi Folks

I put two varieties of Runner Beans in a greenhouse this year
One variety has beans which are purple in colour and are cropping heavily, and delicious

The other variety which should produce Green Beans has grown nicely, and flowered heavily

No action other than that, the flowers which are white, are turning yellow/orange and falling off, with no sign of a bean forming

Both varieties look very healthy, and as I have water buts, are well watered, and I gave a few doses of Tomato Fertiliser.

I also have a climbing variety of Pea, which is producing lots of peas, but the one runner bean variety has stalled

Any ideas, please

One_Of_Shanks

Do you leave window/flaps/door open? Is it possible no insects getting to pollinate the flowers?
Could temps be a tad too hot also if no air getting in?

martinn123

One_Of_Shanks wrote: »

Do you leave window/flaps/door open? Is it possible no insects getting to pollinate the flowers?

Yes, Sliding door open all day, plus open vent in the side wall

Thanks

One_Of_Shanks

You might have already read this page online but some good info here for this exact problem.....


What is the problem?
Even under ideal conditions, sometimes more than half of runner bean flowers may fail to set bean pods. If significantly more than this fail to set pods, yield is noticeably reduced.

What causes the problem?
The main causes of failure to set pods are:
Lack of moisture at the roots
Poor soil or growing conditions, such as acid soils below pH 6.5, pest or disease problems, frost damage, lack of nutrients or organic matter
Lack of pollinating insects, perhaps because of cold, wet or windy weather
Very hot weather, especially at night, which inhibits the germination of pollen grains, interrupting the pollination and fruit-set process. Cropping should resume in September, once the nights start to cool down
The presence of more attractive flowers for pollinating insects nearby. The number of pollinating bees visiting runner bean flowers often increases after the end of July, when more attractive sources of nectar such as white clover and lime trees have finished flowering
Nectar-robbing bees, which rob the sweet nectar from the runner bean flowers by biting a hole at their base, without entering the mouth of the flower and coming into contact with the pollen-producing parts. Nectar-robbing makes flowers unattractive to pollinating bees and insects
Birds, especially house sparrows, which peck at the flowers, making them harder for insects to pollinate
Infrequent harvesting: it is important to pick beans every two or three days, otherwise the pods will start to swell and set seed, which inhibits further pod production


Controlling the problem
The following steps have been shown to help improve pod set in runner beans:

Plant or sow runner beans into soil that has had plenty of organic matter – such as well-rotted manure – added the previous autumn, as this will aid moisture and nutrient retention around the roots
Lime the soil before planting if the pH is below 6.5
If sowing outdoors, wait until mid-May or June to sow when frosts have passed
Apply a mulch of organic matter over the root area, to help conserve moisture
Plant in a sheltered site, as this will encourage bees to visit and pollinate the plants
Rotate the crop each year, never growing it in the same site for two years running. This will help avoid build-up of pest and disease problems
Water in dry weather, giving 5-11 litres per sq m (1.1-2.2 gallons per 10 sq ft) twice a week throughout the cropping period
Don’t mist or syringe the flowers with water (as used to be advocated) as this has not been shown to help pod-set and may deter bees
Take care when applying treatments for aphids or other insect pests of runner beans, because the pesticide could also kill bees and other pollinating insects. Spraying at dusk will reduce danger to bees
Where birds are a problem, try growing a variety with different colour flowers the following year, as this may deter the bird pests. If this does not work, consider growing a dwarf runner bean variety such as ‘Hestia’ or ‘Pickwick’, which can be netted against birds

Hocus Focus

I think that runner beans grow perfectly well outdoors. In my experience the only thing to harm them has been drought. (I'm growing beans from seeds that I got from my mother many years ago, that she in turn got from her father).
Why not use the greenhouse space for something more tender/exotic?