Pollinators can definitely be a huge factor. I found out recently that the reason seedless bananas don’t ever set seeds isn’t because they can’t – most of them can! They don’t usually, being triploid, but there are some cultivars that are a little bit fertile.
The thing is that they’re self-infertile (and monocropped), which is why grocery store bananas never have seeds. Meanwhile, when they’re grown in a back yard, they’re in an ecosystem that doesn’t have their native pollinators, which are bats. So if you want a seedless banana plant to set seeds, you need to have two compatible cultivars flowering at once, and you need to know how to hand-pollinate them.
Figs are like that too, only worse, because you can’t hand-pollinate figs. You have to have fig wasps.
I wonder if runner beans are kind of the same way?
I have an abundance of pollinators and many like the runner beans, even the hummingbirds probably pollinate them, so I’m sure pollination isn’t the problem. Runner beans just don’t like it here, pods if they form at all, tend to drop off while still very small.
Replanting my own seed and mixing in new kinds, for decades, hasn’t significantly improved the situation. Although over the same decades, changes in the weather have accelerated in the opposite direction to what they seem to like.
For sure, I plan on sharing what I can from the runners through this group’s seed exchange next winter. Fingers crossed!
I’m not sure about the pollinators, but I have an abundance in both gardens. I mostly see bumble bees on the white runner flowers.
FYI, our normal summer temps are about 85-95F. Of the two gardens, one is higher altitude and goes down to 50sF at night, and the other to 65-70F at night. The white runners seem to have preformed more or less equally in both locations…maybe a bit better in the warmer spot!
The more I think about this, the stranger it seems. Why would runner beans be less responsive to landrace techniques than other crops? It looks like several people have been trying for some time to adapt runner beans to their locations, with a notable lack of success.
@HAnderson, that’s very interesting that your runners produce well in that climate.
I imagine lack of suitable pollinators may be a challenge to landracing anything. It’s an interesting consideration to factor in.
Perhaps I ought to try hand-pollinating this year. If so, I could try crossing Heidi’s white runner beans with the other varieties, in order to see if I can get those productive-in-heat traits into beans with other colors.
If bumblebees like runner beans, that’s a good sign! I have those in my area. I’ve seen a wide variety of different kinds of bees in my garden, which I take as a very good sign.
I should say the hummingbirds visit them too, even the white flowers. But I’d say the white bean variety does better than the more typical scarlet runner type, and the hummers love those red flowers.
Runner beans aren’t obligate cross pollinators, correct? So even without pollinators, they should be self pollinating and producing?
I will defer to those in the know (I think @RayS for one is landracing runners as well) but a cursory internet search suggested that perhaps runners do not self-pollinate the same way common beans do, instead primarily depending on insects to move the pollen. Doesn’t rule out other issues, but, seeing as it’s much easier to breed for growing conditions than to change a plant’s pollination mechanism, a lack of insect pollination would seem to make more sense than runners being intractibly resistant to directed selection
@H.B , @UnicornEmily , @HAnderson ; maybe it could be a combination of two factors; a need for insect pollinators that may or may not be present in a particular garden, and pollen that has limited viability under certain climatic conditions?
The way I’ve heard it (I’m not sure whether it is accurate) is that while runners, like other beans, don’t need cross-pollination, they do need insects to “trip” the flowers—and that the same insects will result in quite a bit of cross-pollination if two or more varieties are grown side by side.
Could there also be a bit of day-length sensitivity going on? Some people online suggest this is a problem, but the evidence is inconclusive.
Wow I never expected my question to spur so much discussion. How exciting to be part of such a lively forum
I don’t know a lot about the reasons why fruit doesn’t set in the heat, but I just want to chime in that I am pretty sure its not a day length thing because they can be grown in a milder condition at the same latitude (e.g. on the coast).
My intuition tells me that lack of fruit set is not for lack of pollinators because there are so many pollinators buzzing and crawling in our garden through the season, but I can’t say for sure. Is it true that there are some pollinators whose lifecycle has not begun until the cooler temps set in at the end of the season? I don’t know enough about insects to say.
I notice a few beans first setting when nights start cooling down and the days are just starting to cool down. They respond to that edge with beans very succinctly.
I look forward to hear from more knowledgeable people, and definitely excited to hear about @RayS experience with landrace scarlet runners!
I’ve read that runners are happy selfers provided something like a bee or hummingbird ‘trips’ the flower, as @MalcolmS suggested above. But this action also leads to outcrossing, not at a terribly high rate but supposedly a good bit higher than common beans. @idyllwild, you can read about our runner bean landrace here.
Thank you for sharing the runner bean landrace thread @RayS ! It was interesting to read about your trials and interest in perenniality. I am curious, did you happen to note any varieties set beans better than others during the hot season? You mentioned dutch white produced more, do you think that’s because it was setting beans earlier in the season while it was still hot, or do you attribute it to something else? I am also curious about the mexico runner variety since much of mexico is very hot.
The two best producers among those we grew last season were Dutch White and Painted Lady. I don’t know what to attribute that to. Comparisons are not reliable when starting with seeds of different age.
This season we just let those that came back from their tubers grow, not planting any others in that area as we want the seed specifically from those plants that came back. We grew a patch of Painted Lady elsewhere just for beans but a little late it seems. Frost has come extra early this year. We’ve already had one, very mild, with more due in a few days. The beans won’t last long even with very mild frosts.
The Mexican runners were part of a mix someone gave me. Most died out, I think because of day length sensitivity, but an orangey one and a grey speckled one have survived. Both flower quite late but neither have shown any inclination towards perenniality so they are being dumped. Mexico may be closer to the equator than the US but much of the land area is at high altitude so quite cool, especially at night.
Thank you so much for sharing this info. Our zone 7 seems too cold to think about perenniality based on what I understand from reading your other thread. But I’ll have to try Dutch White and Painted Lady to see if they perform better in our climate. I don’t think I’ve grown either of those varieties yet.
Well after some deliberation, I’ve decided to start my own Runner Bean grex/landrace! Given that I love growing them even when yields are scant, it should be enough motivation to keep growing them, at least for several seasons to see if my selections make any difference. I’m sourcing a variety of beans now.
We are going to try a runner bean grex/landrace too in our seed garden in zone 8b (just south of Portland, OR). I’ve been collecting a variety of seeds for our attempt.
I have 2 small plants growing right now, thrown a some seeds in the ground at the end of August. We’ll see how it goes with usually mild winters here, but occasional harsh and strong winds will probably be the end of them. Or I might throw some protection over for those days…
“As an annual suites hardiness zones 1-12. Heat zone: 12-1. As a perennial hardiness zones 10-12. Requires a warm sheltered sunny position in a rich well-drained soil with plenty of moisture in the growing season[1, 16, 37, 200]. Dislikes heavy, wet or acid soils[16].
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Plants are perennials but are often grown as annuals, especially in the temperate zone. Plants flower under long day conditions, which is ideal for temperate regions[200].
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The perennial roots will survive mild winters outdoors in many parts of the country, especially if given a protective mulch in late autumn, they will then give an earlier but lighter crop the following year. They can also be dug up in late autumn and stored like dahlias in a cool but frost free place over winter and replanted in the following spring.
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Phaseolus coccineus ssp.polyanthus (Cache Bean) is also worth considering as a carbon farming plant. It is similar to Phaseolus coccineus but more suited to tropical highlands and semi-arid conditions.”
