French bean options

Broad beans will cross, unless they flower at different times.
French beans may cross if close together - Real seeds suggest keeping them 12' apart.
Good advice at How To Save Your Own Seed at Home

Cheers VC, looks like I'm only growing one French bean this year but which? I take it I'm safe that broad beans won't cross with the French.

Broads don't cross with the French

You could always throw some enviromesh over one of the varieties at flowering time, so the buzzies can't get to them.

Very true Thelma, only a couple of problems with that. Firstly I'd need to have some enviromesh and secondly and probably more difficult to fix I'd have to remember. Likely hood is I'd plant all the frenchies forget to mesh one set and they'd flower n screw my seed saving idea. I'm hoping that as broads and French don't cross I could build one set of supports and interplant them french and broads together.

Excuses excuses LOL

Will beans self pollinate without help from insects? If not, environmesh may well leave you with no beans!

French beans don't need any help from insects to be pollinated, they are self pollinating, which happens before the flower opens.

Now that's an interesting point Scarlet. If they're self pollinating and they do it (as it were) before the flowers open then why do you need to be careful about seed saving? Also how does anyone get any new varieties?

Well that's where it gets interesting.....insects can get in and move the pollen around. I've read if you just choose beans to save that are in the middle of the row you are are less likely to have any crosses. I've never had any crosses that I've been aware off, but Thelma has, so it can happen.

French beans are mainly self-pollinating and don't need any help, but they are sometimes cross-pollinated by insects, especially in organic gardens with plenty of insect life.

If you want to keep your varieties pure you can separate them by distance, or with some other tall barrier crop that they won't cross with e.g. runner beans. Or you could grow them at opposite ends of a long row and only harvest the ones at the far ends for seed and use the middle ones that are more likely to cross for eating.

It can also help to have two very distinct varieties so you can easily recognise any crossed offspring the following year and weed them out. The two you've mentioned are quite similar so it would be hard to tell if they had crossed.

Broad beans are partially self-pollinating but the flowers need to be tripped by visiting insects, so if you shut them out you won't get much of a crop.

I also don't see how one set of supports is going to work. Climbing Frenchies need tall canes or strings to twine around whereas broad beans don't climb at all, but might need some lower level support to stop them flopping over.

Small wigwams work well, 2 beans per pole. They don't take up much space.

As Scarlet said, bees can get into the flowers and mix the pollen from different plants after it has been shed.

Serious bean breeders who want to cross two particular varieties and eliminate all possibility of self-pollination need to open the flowers of the female parent variety at the right stage and remove the anthers before they are mature enough to shed any pollen. Then they hand pollinate the stigma with pollen from the male parent variety. It's apparently very tricky and I haven't tried doing it yet, though I did try it with peas.

You only get a few F1 seeds for a lot of fiddly work, which is why you don't see any F1 varieties of beans (or peas). But one can be enough to start a breeding program, as there will be lots of variation in the F2 generation, which can be selected from and eventually stabilised into a new variety.

I guess if you just want to increase the chance of getting some crosses among the self-pollinations you could hand pollinate without removing the anthers. But I think new varieties often start with someone noticing an interesting natural cross by bees.

I have had occasional seeds in a packet that turned out to be crossed. One very obvious example was a Hutterite Soup Bean plant that climbed when it should have been dwarf, had mauve flowers instead of white, had long rounded pods instead of short flat ones, and shiny black kidney-shaped seeds instead of chunky creamy ones with a dark hilum. I keep meaning to grow them out and see what I get in the F2 generation, but I haven't done it yet.

Somehow they managed to cross runner beans with French beans to get the new self pollinating runner bean varieties. I wonder how they did that?