Beans are reluctant to cross, but it can happen.

Better to separate each variety and save seed from the best plants. :-)

Oops! It's possible that the Roma beans can cross with the Fortex and KW wax beans, too, since all three are Phaseolus vulgaris. But not the limas, which are Phaseolus lunatus forma salicis. And not the Southern peas (cowpeas).

So I may have to rethink how or whether to even do this.

iam3killerbs

Yes, I've seen really conflicting information on the crossability of beans. (I think people mean the Phaseolus vulgaris varieties.) It ranges from loud assurances that the crossing averages only about 1.5% to claims that it happens more often than that. And the rates seem to be different for bush beans and pole beans.

I've read that some old-timers don't worry about crosses but keep all their saved bean seeds mixed in a "bean jar" for the next year, plant them and take the crop mixture they get! Actually, that appeals to me since I'm not a fussy gardener except about a few things, but I don't want to mix beans when I cook them! I have grandchildren who want their beans to all be the same kind! So I suppose the beans can be separated after harvest if one decides to do that.

Anney, if all you want is dry beans, a little crossing won't matter; but for snaps - such as the 3 common beans you list - it often does. Most modern snap beans are stringless, or develop strings late. When crossed, however, the results can be unpredictable in flavor & size, and often less palatable than the parents.

P. vulgaris beans are self-pollinating, and usually have a low percentage of crossing. In my own saved seed (of 33 varieties), crossing has so far been in the range of 0-1%, with zero the more common. I try to use at least 30 feet of separation between varieties, with other flowering crops planted between them; this significantly reduces the chance of crossing.

Given my own low rate of crossing, it would seem to indicate that heavier crossing is unlikely... but it does occur. Several beans I received through trades were heavily crossed, with one about 50% (which I was able to purify), and one so severely crossed that it was hard to identify the original strain among all of the crosses!

There are some who have grown different varieties in close proximity for years, with little crossing; but I would not recommend doing so. Try to use as much distance between different varieties of the same species as possible. If that is not practical, at least alternate with rows of other flowering crops, including other bean species.

Limas & runner beans are very prone to crossing with others of their species, even over distances of 1/4 mile or more; so to save seed, grow only one. They will not cross with P. vulgaris though, and are more attractive to bees, so they make good barrier crops. I plant one of each per year, per garden (my two gardens are 6 miles apart). For the limas, I sometimes plant in multiple locations throughout the garden, between different bean varieties.

Cowpeas will not cross with the other beans, but they can cross with yardlong beans, which are also Vigna unguiculata. Like common beans, they do not seem to be especially prone to crossing; but because of their larger, more attractive flowers, I use more space between them, at least 50 feet. I have yet to see a cross.

Other techniques can also reduce crossing. Instead of one long row, plant 3 short rows of a variety, and only save seed from the middle plants of the center row. Alternatively, plant all of your pole beans in one long row, again saving seed only from the center plants for each variety (this also makes building the trellis easier). With pole beans, even if you only save seed from 2-3 feet of row, it will be enough to last for several years.

You could also grow a seed crop in pots, some distance away from the main garden... one variety per year, in a rotation. I do this for rare varieties, or when seed is in short supply. Pole beans do well in large pots, provided they are kept watered.

Or if family/friends also garden nearby, form your own "garden coop"; each of you grow one variety, and share the harvest. Using that method, you could each save pure seed from one variety.

One last note. When the discussion turns to seed saving, many (self included) can get caught up in arguing the technical aspects. But perhaps the real question is: "how important is it for the seed to be pure?". If you are only saving seed for your own use, and the varieties are commercially available, a few crosses are no big deal. Just throw away any off-color seeds, and kill any off-type plants as soon as they are identified. Worst-case scenario is that if crossing becomes excessive, you need to buy fresh seed, and start over.

On the other hand, if the seed is an irreplaceable heirloom, or if you intend to share seed with others, then everything possible should be done to ensure seed purity.

Wow, this post kind of got away from me... too used to working late hours. Night all, have a great holiday.

Hey! Checking in here! I've not been around much with the spring rush and our son getting married. Thought I'd add my two cents on this one.

I've had crosses of cowpeas and yardlongs when they were planted side by side. Farmerdilla informed me that they are more prone to crossing than p. vulgaris beans, which agrees with what Zeedman stated above.

Years ago, back in '85-'86, when I first started saving quantities of bean seed, I had a number of crosses between bush beans. These were all planted in rows, serially. That is I'd do part of a row of one variety and then another part of another variety, etc. Apparently pollinators worked down the row, and quickly, we had crosses. Seed Savers Exchange used to do articles in their year books on basic seed saving techniques, and from them I learned the basics. I now plant each variety with at least 16' of distance from others, though, for instance, I could plant closer as long as my "seed plants" are further apart. For added security I often use different species (limas, cowpeas, etc.) as barrier crops between my p. vulgaris varieties (and vice a versa). This really seems to help. At any rate, I have not had a cross since '86.

I have a system for seed production. With pole beans I grow my seed either on tripods or single poles. A single pole easily produces enough seed for my own use, and that of a couple of friends. A tripod normally produces between 1 quart of seed and 3/4 quart of seed, which is what I need for exchanges on a larger scale. I always make sure that my seed plants are the most isolated from other varieties, and often, they are surrounded by plants of their own variety.

I'm not that much into bush beans. But I do have a couple varieties. I normally plant at least 5' of row (often in block form) for seed. You'd be amazed how much seed, however, a half dozen plants can produce. For reasons of genetic maintainability, I do try to save seed from no fewer than a dozen plants. More is better.

I bet I could get enough cowpea seed for a 32' row from two plants, if I gave them poles to climb on, and didn't eat any of the seed. But I actually save seed from nearly every plant I grow, every year. This is simply because I let seed dry on every plant and it is easy to save some. But if I was planting a dedicated patch for seed, I'd probably put in about 6' at about 8" between plants.

Here's another tip: if space is limited for seed saving, but you can make arrangements for one or two varieties in a given year, try rotating your seed production. Bean seed is easily good for three years, if stored correctly. So, you could easily do a three year rotation, producing seed of certain varieties every third year. You could still plant and consume all your favorites, every year, as long as you could reproduce seed every third year. I say "every third year" just to be safe. I've had some bean seed last more than five years. One cowpea (yardlong) I grow has actually germinated at nearly 100% from seed over a decade old, and that, stored at room temperature.

Don't forget, when you harvest seed, to dry it thoroughly and then, after sealing it in an air tight container, freeze it for at least two days. Many is the person who has lost their seed for not having done this. Weevils (evil little creatures) inevitably lay eggs under the skin of immature bean seeds. These eggs will hatch out months after the seed has been dried and stored. Most often, when this happens, the hapless seed saver fails to notice what is happening until the entire jar of seed is ruined. So, be sure to freeze your seed. And, beware, when removing the seed from the freezer, that you DO NOT OPEN the jar until it has THOROUGHLY warmed to room temperature. To do so will cause condensation on the seed, which will ruin it, if you fail to dry it again.

George
Tahlequah, OK

Thanks, guys! Some good ideas here! I like two of them particularly. Growing one bean variety per year for seeds, then another the next, and another the next. In containers appeals, too, because they're portable and can be placed in areas far away from the garden and each other if you wanted to get seeds for all of them in the same year. Or alternating years.

This post got me thinking. I have one row (100') of pole beans with two different heirloom beans planted. Part of the row (20') with Rattlesnake pole beans (phaseolus vulgaris) and the other part (80') a bean my uncle shared about 1/8 cup of seed after years of me pleading with him to share called "Greasy backs". I do want to save the seed from both especially the greasy backs as I do not know of any other source for them. Question. Should I remove the rattlesnakes and plant them for seed next year. I do not want them to cross. Thanks for this post anney.

If I decide to start a couple of pole bean plants in containers to use for seed when they're all finished, what's a good size container for them? I have lots of collected 2-liter soda bottles that I've thought I could use for small herbs (and they're the PERFECT size for single onion plants, even if that would be a lot of work and bottles) but would they be large enough for one bean plant in each with a pole to climb beside them? I also have lots of gallon nursery pots. Then I have three five-gallon buckets with drainage (not SWCs).

What's the smallest size I could use?

Anney, I'm not a good source of info for container gardening. Hopefully a more knowledgeable person will check in on that question. Off hand, I'd say you need a five container to raise pole beans, at least, that's what I did, the one time I grew pole beans in a container. Five gallons seemed about right, and it did work.

Gpaintjr, I tell you what I'd do. I'd leave those beans as you planted them. It would be such a shame to destroy the Rattlesnake beans after you planted them. But take seed from the part of the row which is the FURTHEST from the other variety of bean. Then, when you grow that seed out, be sure to destroy any plants which produce plants which have any different traits from what you observed in that variety this year. Even planted side by side, my guess is that the vast majority of the seed produced, will be pure. I actually planted two pole varieties together, on the same pole, last year, to try for a cross. I'm not at all sure that the seed I plant, from that pole, this year, will give me a cross after the first attempt.

George

Thanks macmex, I will let them grow.
Anney, I have grown purple hull peas for several years now and I would say that 2 or 3 plants should give plenty of seed for a 32' row. I have grown in rows and in beds 4'x85' and they seem to like the beds better. A lot less weeding in beds than rows. On the crossing thing I am still learning. Mostly from this forum. Thanks

macmex

LOL! I *want* somebody to tell me those 2-liter bottles are large enough to grow one solitary pole bean plant in :-). I think I'll plant two of each green, wax, and roma pole beans that I have far from each other for seeds.

gpaintjr

Yep, I'd concluded that three purple hull plants will be enough to gather seeds from for next year. I may just leave three plants on the end of that bed unpicked for eating and mark them with red ribbons or something. And I can probably leave the two pole lima plants on one end unpicked for eating, too. I won't need to plant them separately since they won't cross with the other beans I'm growing.

I'm an amateur at seed saving, but isn't it best to plant a number of plants for seed then save from a combination of the very best instead of planting just a few for seed and risking them being the lesser ones?

Yes it is. You are correct. Sometimes, however, a person is just doing good to save any seed at all. But, as a rule, what you describe is the best.

George

I agree with George. For preservation purposes, it is best to preserve as much of the original genetic variation as possible... and seed should be saved from a large population whenever space allows. For out-crossing species (such as corn) this is a necessity; but it is less important for inbreeding species such as beans. Many beans may, in fact, be descended from a single plant. I presently have 3 varieties that I brought back from half-dead seed with only one plant.

This is why I like to grow LARGE plantings of my rare varieties. With Tennessee Cutshort, a family heirloom, I like to put in at least 32' of trellis, plus a tripod specially dedicated to seed. Every year, as I shell seed, I select the largest pods with the highest number of seeds to the pod, and these go into my "Select Jar." Yet, I also save some of the "escapees" from the other beans and throw a few in with the "Select Seed."

Yet, for instance, I received seed to Ralph's Italian Heirloom, a Romano, back in 1985. This is a good bean, but not my favorite. On account of a move in 2005 we lost our most recent seed. Then due to rabbits we lost two successive plantings. I dug up yet another old batch of seed, which had only about 10 seed and tried to germinate them in a damp paper towel. This morning I found one seed sprouting! So, we're in business! (Providing the river "don't rise" and the rabbits are held at bay!) This bean is grown by the Seed Savers Exchange, so this one seed isn't the last in the world. Yet, it could have been.

George