Heat Tolerant Scarlet Runner Beans

I am in love with scarlet runner beans but it is hard to get a large harvest. The vines grow and flower like crazy in our zone 7 weather with long hot arid summers. But beans don’t start setting until very late in the season when the evenings and days are cooling down. So there is a short window for the beans to ripen and last year we hardly got any because our summer was so hot and frost came early.

Is anyone growing landrace scarlet runner beans or know of any varieties that are heat adapted will produce more beans in warmer climates?

Thank you!

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Yes, I grow runner beans and no, I don’t know of any that produce. I’ve grown the goofy things for thirty years and rarely get more than enough to plat the next year. Giant vines, lots of flowers, few beans. Hummingbirds love them and I enjoy the hummingbirds, so I keep growing them. Someone gave me some runner/common crossed seeds one time. Even more giant vines, even more flowers, still very few beans.

Oh, that’s a pity! Is runner bean pollen less viable when it’s hot, or something?

I have a runner bean variety from the Four Corners region that does well here in the High Desert (both zone 5 and 8). I sent in some to the runner bean mix in the store! They’re the white ones (not scarlet – they have beautiful white flowers). Right now I don’t have extra to share though because we got a lot of cool late summer rain last summer, and it hated that. Hopefully more this fall! It’s also more of a half-runner variety, so it can grow without support. I originally got it at a seed exchange from Espanola Seed Library (NM). I don’t know if they still have other folks stewarding it.

We also have scarlet runner beans from a local seed/plant nursery – they do less well, but not horrible and they’re so beautiful, I keep trying.

It’s a good question @UnicornEmily – I don’t know much about runner beans. I grew a third variety that I bought from a specialty bean store (for food) last year for the first time (planted in isolation). I was fairly shocked by how much they flowered and didn’t produce seed…although they ended up loving the late seasons rains and coolness, so I did eventually get some seed to save.

I’m planning to plant out a mix this year. Our weather patterns are changing, so having some genetic variation that can handle both extremes would be nice.

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Interesting to hear about! I had no idea this was so big an issue. It is quite strange to me at first glance and I’m curious if struggling to produce in heat is a trait common to many runner beans. I’m working on cold hardy runners, also in zone 6 (planting them for the first time) and it never occurred to me that production in hot conditions might be an issue

Heidi:
Beautiful white bean! :grin: I look forward to seeing it here this season. I planted half my runners in a protected outdoor location in January, well understanding that they might easily rot or be frost killed. If I get seed from two or more distinct varieties I will be very happy, if I get seed from one I’ll be happy. If none of them make it I’ve got the other half of the mix now that more appropriate bean planting weather is fast upon us.

I’ve always had the same problem with runner beans. They grow and flower beautifully, but don’t set pods until October. We usually have a long autumn, so I have had some good crops, but I really wish I could get something from them before then. I’ve been collecting every sort of runner bean I could for a big grow-out to see if I could find more heat-tolerant strains.

Wow thank you everyone for your thoughtful replies! As far as I know it is common for Scarlet Runner beans to have issues producing beans in hotter weather. I understand they produce really well in climates with milder summers.

In our region with long, arid hot summers its hit or miss if anything sets at the end of the season depending how late the heat is and how early the frost is! Last year I managed to get seeds that look viable but they are very small compared to the year before.

@HAnderson wow that is amazing, this is the first I had heard about runner beans that produce well in hot summers. Googling hasn’t turned up any unique varieties which is why I am asking here. If you don’t mind I’d love to follow up with you towards the end of the season to see if you have any extra seeds to share from the “four corners” variety and the local nursery variety that aren’t “horrible”?

@paul that’s my experience also in this climate. Wow your scarlet runner trial / grow out sounds really worthwhile. Would you mind if I followup with you at the end of the season to see if any of your varieties set beans in the heat?

@MarkReed I didn’t even know that common beans and scarlet runners could cross. Amazing!

@UnicornEmily I’ve read that runner bean pod set falls off sharply when temps go above 25°C (~77°F).

Whoa. That makes it sound like they are spring crops, rather than summer crops. Like maybe I should be planting them with my fava beans, rather than with my common beans. Are they frost tolerant? (My fava beans have been doing just fine shrugging off snowfall after snowfall. The point at which we stop getting snow at night is the point at which we start getting 80-90 degrees F daytime temperatures. We don’t have much of a spring!)

If they aren’t frost tolerant, another option might be planting runner beans in July or something as a fall crop. We don’t usually start getting frosts until October. Of course, we don’t start getting daytime temperatures below 80 degrees until we start getting frosts, either . . .

I don’t believe it happens easily; the person I got seeds from had hand pollinated them. I think they gave me three seeds. They all sprouted and the giant mass of vines that grew produced a couple dozen seeds, even less actually than regular runner beans normally do. If I had kept going with them, eventually they might have segregated into something worthwhile, but I didn’t what to mess with building a bunch of giant trellises and my gardens are too small to justify using the space.

@MarkReed thanks for letting me know. Its probably a worthwhile breeding project for someone, just not me in this moment :stuck_out_tongue:

@UnicornEmily No scarlet runners are not frost tolerant like fava beans. They have to be planted after last frost or protected just like common beans. They direct sow very easily and are even a bit more resistant to mulch decomposers than other beans in my experience which is a big plus for me because I mulch heavily. There’s no problem planting them at the beginning of the season, actually it gives them more time to establish and they keep flowering right through the end of the season vigorously.

That does sound like a fun project. Were the flowers or beans pretty? I’m very curious about how those would segregate.

The flowers were very pretty, red and bi-color red/white, and extremely abundant, the beans were few and far between. The pods were also small, nothing like I expected from a runner bean cross. I planted them on a 10 foot (vertical) piece of cattle panel, supported by a steel t-post. They overshot the top and flopped back down, grew up again and flopped down again, multiple times. The t-post held the whole thing up, but the top of the cattle panel folded over by the weight, it was a mess, all from just three seeds. I think, but not sure that the few beans I did get all came from just one vine, the other two made none.

It would be fun to see how they might eventually turn out, maybe backcross to some more common beans, I just didn’t have the time or space for it. I gave the seeds away and never got a report on how they did. I suspect more of the same, giant vines, no beans.

I can see why you felt it wasn’t worth continuing the project! That’s an awful lot of space and bother for so little productivity. It sounds like a good project for someone with a lot of space, and/or someone who would be content with the plants being mainly ornamental for awhile.

I can easily see how very pretty and abundant flowers may be enough for the right gardener to want to continue the project. Especially since it would be fun to see how a cross like that may turn out long-term.

I think I have similar priorities to you: I have a small growing space, and I want food! :wink:

Yep, it’s fun to experiment and tinker with this or that but not at the expense of producing stuff to eat. Just plain runner beans by themselves provide plenty of decorative value and once in a while even make enough to eat a few.

(Wry laugh.) So are they not all that productive most of the time? I love how huge the beans are, and I’ve been hoping that would mean a nice, big harvest.

No, they don’t produce well at all here. I grow them mostly for decoration and because the hummingbirds like them. Rarely, if the weather is just right, with periods not too hot, they make enough I can eat some and still get seeds. When I grew a whole bunch of different kinds, they apparently didn’t cross much either because all the different colors disappeared. I think they are much more suited to cooler climates like in northern Europe. From her description of climate, I bet they might do well for @julia.dakin.

I would guess in your climate, lima beans and maybe especially cowpeas would be much more productive. For me cowpeas seem capable of outpacing common beans. Lima beans are not as productive but with introducing new kinds and selection I’m seeing improved production on them. Both are also more tolerant of heat and drought than common beans, more resistant to bugs and disease too. I expect in coming years to see them becoming more dominant in my garden but for my purpose’s runner beans seem to be a waste of time and effort.

Runner beans are more for people on the NW coast or areas in the NE. At my sister’s house in coastal Maine, they produced like crazy but sometimes had trouble drying down mature seeds.

I’ve got cool nights here in Denver, but the runner beans still struggle. They grow, more or less, but they set very few pods. I just love the plants and seeds, and I like that they attract hummingbirds, so I keep trying.

I think they are just generally finicky about setting pods. Even English gardening books and websites mention various tricks to get the flowers to set, so it must not be an exclusively warm-climate problem. I’m wondering if it has to do with the kind of pollinators that are around as well as the weather. They have different pollination mechanisms than common beans, at least.

The only time they grew at all decently for me was when I was gardening at a plot about a mile from my house, further down into the river valley and near a pond and marshy area. The microclimate would have been a bit different, the soil would have been better, and I imagine (though I don’t know for sure) that different kinds of insect pollinators would have been dominant.

Ahhh, that’s a pity. They’re so pretty, and I’ve read that some can perennialize, which sounds neat.

So it’s sounding like runner beans may be finicky about their temperature range, and want it neither too hot nor too cold? That sounds ill-adapted to a climate that is mostly extremes. :wink:

Well, I’m still going to give them a try, and I’ll keep in mind that I probably shouldn’t count on them to succeed. Maybe I’ll see if I like the taste of the leaves. If so, it might be okay if they’re not very productive with beans.

Lima beans do look promising! Last year, my only plants to survive extreme drought and neglect, as well as lots of frost, were Fordhook 242 lima beans. They tasted delicious, too. I saved half of them (especially the biggest) for seed. I also got given some Christmas lima beans from a neighbor who has been growing them for years and saving her own seeds, which sounds promising, too. They’re pretty, and she says they’re tasty.

Yeah, I suspect cowpeas will do really well here. I’m really hopeful about them. Tepary beans, too. And I suspect there are a number of varieties of common beans that will do great.