In my OPINION that's just a hair close. But the use of the lima as a separator is very good. I like to give my beans a minimum isolation of 15' with a tall separator between.

Some insects can cause cross pollination. It seems some locations have more problem with this than others. I just grow with the most isolation distance possible and forget about the insects. Haven't had a cross now since the 80s.

George
Tahlequah, OK

George

Another early bird!

Thanks. I may be able to move one of the bean patches so that it's about 15 feet from the other at the closest point, so I guess that'll have to do it for this year. Maybe I'll order more seeds next year and see if I can plant them farther apart than that.

It depends on whether you want absolutely pure seed. If you have the space, I would recommend at least 50 feet between bean varieties with other flowering plants such as corn and squash between. The problem will be solitary species of bees such as masons and a few bumblebees. They tend to fly from bean plant to bean plant tripping the blossoms to collect nectar and a bit of pollen. They will easily fly short distances, but the likelihood of crossing gets less as the distance increases. 1/4 mile is enough to produce commercial seed and 1/2 mile is adequate for foundation seed which requires very high purity.

DarJones

Anney,

Are you suffering from separation anxiety? :-)

Sorry, I couldn't resist!

Dennis
SE Michigan

FP

I don't have that much space! But I do have a question. Is there any way to tell if the beans have cross-pollinated by their color or the color of their pods? IOW, if I planted them too close to prevent cross-pollination, saved the seeds, and then planted them NEXT year, would I be able to tell which ones were the result of cross-pollination?

Just wondering...

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Dennis

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Are you suffering from separation anxiety? :-)
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Yeah, maybe I am :-)! I'd like to plant them close together if possible -- but I'm absolutely enamored of the way green and yellow podded beans look when cooked together, though I haven't identified much of a difference in taste, so I guess I'll have to keep them separated...

"Is there any way to tell if the beans have cross-pollinated by their color or the color of their pods?"

That can work, if the varieties you grow have differences you can observe. I had some crossing between two varieties which have flowers of different color. Now, when I see a purple flower amidst the white ones, I cull out that vine.

Required isolation distance is affected by several factors. In a small home garden like mine it's kind of futile to depend on isolation so I don't try. I do try to alternate rows types which can't cross. The case mentioned above was the only cross I've had, so far as I know. It's good enough for me. When I offer that one for trading I make it known that there may be some impurity.

Jim

There are some really great existing threads on this topic within this forum, only one "Search" away.

That being said... I'll pretty much agree with most of what has already been posted. Beans can cross, and I've received plenty of crossed bean seed from exchanges. But with only a few exceptions, the rate of crossing was very low, less than 5%. If you are only saving seed for your own use & are comfortable with having a few oddities each year, then little separation is necessary.

On the other hand, if you intend to exchange seed with others, or if you are preserving a rare heirloom, then you should take stronger measures to reduce crossing. The use of a barrier crop (such as the limas) is helpful, as is providing as much separation as practical. The two in combination can be very effective. I've used 25-30 feet minimum separation, with several rows of flowering crops between as barriers, and have yet to see a cross. Placing the two varieties on opposite ends of the garden, or across the yard, is usually sufficient.

This technique works well for common beans (Phaseolus vulgaris), peas, cowpeas, soybeans, and tomatoes. Limas & runner beans are more attractive to bees, and more prone to crossing, so you should grow only one if saving seed... and even then, you might get a cross from one of your neighbors.

Any crosses which might occur would not be visible in the saved seed, but would show up in the plants the following year. For that reason, it is best not to plant similar varieties close together when saving seed... such as two white-seeded varieties. You would want to rogue out any crosses before or at flowering, to prevent further contamination from occurring. You can & should rogue the dry seed also, but this is no guarantee of purity, since more crossing could have already taken place.

Fusion & I are purists, but this is not as difficult as it sounds. Many people save their own bean seed successfully.

zeedman

Sorry to repeat a commonly-asked question.

I did find GW search information on the best physical spacing of beans and which beans can cross-pollinate, but what I actually wanted to know was how far apart to plant the vulgaris patches to prevent that cross-pollination.

I got the answer here, and it's obvious I'll probably have some cross-pollination anyway since my garden area doesn't cover hundreds of feet!

Maybe I should just give up trying to keep the beans separate, since my reason was only for their aesthetic-on-the-table look, and save them all together in a garden bean jar, as someone mentioned elsewhere.

Wonder if the green ones would become dominant after several years....

You can also search, find an old thread with lots of information, and comment on it, even if it is years old, and it will bump up to the top again.

That way helpful regulars like Zeedman who always answer these kinds of questions, sometimes several times a year, can add to their comments instead of having to retype them in a new thread again. Maybe the other posters of the searched thread will come back with more information based on experience since the thread was last bumped. You could end up getting more info than this way.