Why are the blooms falling off my scarlet runner beans?

Murphysboro, IL(Zone 6b)

Hello, all! This is the first time I've grown runner beans, as opposed to bush string beans. The flowers are gorgeous, but when they're done blooming, they fall off as if they've been snipped with tiny scissors, leaving just a blunt stalk behind. With all the beans I'm familiar with, the little green leafy cup that connects the bloom to the stalk stays behind, and the bean grows from there. With the runner beans, this cup (anyone know the botanical term?) is falling off with the spent blooms.

Nutrient deficiency? Flowers not being pollinated? Some kind of pest snipping them off? The beans are growing in a large self-watering container, and they look generally lush and healthy; I put up a 5 ft. trellis, which turned out to be way too short. The plants have reached the top already and they're searching for more. We live out in the woods with tons of flying insects -- I can't believe there's not *something* out there that would pollinate these beans....

Fayetteville, AR(Zone 6b)

I had the same question and was told it was probably too hot here for them. Maybe you have the same problem?

Ayrshire Scotland, United Kingdom

the water fluctuation and dry heat causes this problem as it is like stress to any flowering plant, dont know if you have water restrictions, but if you still have some plants of this type that have not flowered yet, try to break up the surface of the soil along the rows so that air and water can penetrate the soil and give them a good soaking, after that a good mulch of say lawn cuttings will help keep the roots cool and the water wont evaporate so fast, it is a good idea to always try to water them at about the same time each day/night try not to get water onto the foliage if you water in the cooler evening when the heat is off the sun as you could cause mold to grow, the next time you grow any bean family, try to dig out a trench about 8 inches deep and through in as much organic matter into the trench as they like a good rich soil and this helps to retain some moisture for the root system, also just to be on the safe side, do check out your pants to make sure you dont have any insects that are eating the flowers as they form, some forms of bee's are known to cut the flower heads off plants as do ear wigs, good luck. WeeNel.

Murphysboro, IL(Zone 6b)

Thanks for the input! They're in a self-watering container so they're kept nice & evenly moist -- I'll bet it's the heat. We've had quite a few days over 90 degrees already. :: crosses runner beans off list for future ::

Tuscaloosa, AL(Zone 7b)

Seems to me that I read on another thread recently where Farmerdill said that scarlet runner beans don't like the heat and they have to be grown in cool weather. I have some seeds, but I'll hold them until fall.

Karen

Ayrshire Scotland, United Kingdom

No too many things from the bean or pea edible family really like a lot of heat, I have to apologize here as sometimes I forget just how hot you guy's do get the sun, I am just the opposite here where it is the cold or short sun season that causes me the problems, beans dont like a lot of heat and also they like rich humus soil under the roots as the are greedy plants, but good luck anyway, WeeNel.

Fayetteville, AR(Zone 6b)

I do like the idea of the trench full of organic matter. I may try that with all of my types of beans next year.

Ayrshire Scotland, United Kingdom

Hi Chico, Every spring, I dig out my trench for the bean/pea family, then toss all my kitchen waist into the trench for a few weeks/months, then cover it with my own organic home made compost, then fill the trenches back up again with the soil from the trench when I dug it out, I top fill it the day I go to plant the seeds (I make the trenches about 8/12 inches deep) I also soak the trench with the garden hose before I plant the seeds as this seems to help speed up the germination in the open ground, or I start the seeds of under cover and plant the small peas/beans when the weather is right, I then dont have to feed them all season, all I do is tie them up the canes as they grow, hope this gives you some other ideas, good luck, WeeNel.

Nellysford, VA

I have just posted the same question, we are hot as well... I remember when we grew them at home in the old days gardeners discussed manual pollination and also spraying the blooms with a water mister to help them set. Certainly heat was never a problem in England.

Murphysboro, IL(Zone 6b)

Yes, to lend further evidence to the heat theory, our temperatures dipped back down to the low 80's for a couple weeks, with low 60's at night, and I finally have five or six beans developing on the plant. But out of 100-200 blooms, this is not too impressive! The hummingbirds continue to enjoy the flowers, though.

Nellysford, VA

I am finally getting a few beans developing, enough for 5 bean salad!!

Dickson City, PA

I am having the same problem, tons of flowers, all falling off, but I have noticed very few beans that are progressing nicely. I would say 80% of the flowers fall off. The weather here in PA has been hot, lots of rain, and my other beans are doing great, but these. I water at the base when it's too hot early in the morning and late in the evening if we have a over 80 degree day. The bees are pollinating so that's not the problem. So I will do what the other commenters are doing, a trench, I'll put worm castings down and some other goodies. If anyone else does anything different, please let me know. This is my first time using these runner beans. I never thought these beans would be difficult, but they are pretty to grow.

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