Self Pollinating Runner Bean 'Firestorm' dropping flowers

[GardenNinja]

I am growing runner bean 'Firestorm' this year on my balcony because they supposed to be self pollinating, but all the flowers are slowly dropping off. I am growing four to a 35cm plant pot and the plants seem to be thriving with healthy leaves. One of the plants have already reached the top of the 8 feet bamboo cane structure which I have tied together for support.

There are several large flower clusters and each flower appears to be healthy so I am wondering why they are not forming pods. Any advice is greatly appreciated!

[rustylady]

I would say your pot isn't big enough and is probably drying out. I'm also guessing that as they are on a balcony it's quite windy.

Increase the watering and try misting the flowers with plain water in the evening.

[GardenNinja]

Thank you, rustylady. I have tried to give the beans as much shelter as possible, but yes the balcony gets incredibly windy. I don't think the watering is the issue as the pot has a water reservoir and I always make sure the compost is consistently moist.

I have one spray bottle which I use to give my pepper plants a boost with epsom salt. Would it be ok to mist the flowers with the epsom salt when I spray my peppers or should I only use plain water?

[rustylady]

I think plain water would be better, but I don't suppose the Epsom Salts would do them any harm.

[darcyvuqua]

To be honest I had the same problem last year they were also in pots

[Potstubsdustbins]

Growing Firestorm for the first time this year, so far no problems with bean set.

I agree with RL the container is to small I have grow runners 3 to a 50cm pot but that's as far as I would like to go. This year they are all individual buckets.

What are you feeding them on and how often they are big hungry plants.

Potty.

[Two_Sheds]

"the old idea that misting runner beans with water helps them to set pods is a myth. It is more likely to hinder, as pollinating bees don't like visiting the flowers when they are wet."
Sue Stickland: Runner beans | Life and style | The Guardian

"Don’t mist or syringe the flowers with water (as used to be advocated) as this has not been shown to help pod-set"

Runner beans: failure to set pods / Royal Horticultural Society



That's another old gardening rule that we used to all be told, that has now been tested & proven not to be true

[alldigging]

Water them. Stuff in pots always takes more water.

[GardenNinja]

Growing Firestorm for the first time this year, so far no problems with bean set.

I agree with RL the container is to small I have grow runners 3 to a 50cm pot but that's as far as I would like to go. This year they are all individual buckets.

What are you feeding them on and how often they are big hungry plants.

Potty.

I was feeding with a 4-4-4 vegetable fertilizer with seaweed extract. Since they have started flowering, I have switched to Tomorite. They are fed at half strength every 3-4 days.

Should I cut down two plants and leave two? I'm not sure if this will be of any benefit because all of the plants are pretty mature and nearly reaching the top of my 8 feet support. If I cut two off, I'm assuming their roots are already established and have taken the room that I would want to make for the remaining two.

[rustylady]

Leave them as they are, just make sure you keep on top of the watering and feeding.

[Two_Sheds]

You're overfeeding, and that will give you lots of lush green leaves at the expense of flowers/pods.

Beans can make their own nitrogen from the air, onto nodules on their roots, so don't need to be fed by you, until the pods start forming

"To boost your [container] crop, feed with liquid tomato food once every two or three weeks after the plant starts flowering." Magic beans! How to grow runners successfully

[GardenNinja]

Two_Sheds, thanks for the link! The problem that I have is not the absence of flowers (I have plenty of them) but that they won't form pods. I am growing french beans as well, and it seems like they are forming pods after flowering with no issues. Does overfeeding lead to flower drop in runner beans but not french beans?

Also, I'm a bit confused with the nitrogen production. If the roots need bacteria to make nitrogen, are there enough prokaryotes in container media to do this?

[Potstubsdustbins]

The best way to feed any pot grown veg is to water between every feed this will flush the compost and make over feeding near impossible.

Now they are to a good height to need to give them a good high potash feed, Tomorite as 2Sheds suggests is very good. However due to the amount of plants in your container up the dosage rate to about double what it says on the can.

Potty.

[GardenNinja]

Thanks, Potty. I have been feeding them Tomorite since they started flowering. You mentioned the flushing of compost, but I have a sub-irrigated planter which has a water reservoir at the bottom so the plants get all the feed given to them. Do you think I should still double the feed dosage despite this?

[Potstubsdustbins]

That's a hard one as I have no practical experience of that. Sorry.

Potty