Snap bean landrace/grex development

Hey folks,

Growing up, we grew mostly Kentucky Wonder & Blue Lake bush beans, so that's what I'm used to in a green bean.

This year, I'm working on expanding my snap bean grex.  I have some saved OP seed from the past 2 years of mostly well-known tried & true varieties that I'll be growing out (bush & pole) in addition to about 2 dozen more purchased varieties to add to the mix.  There's a wide range of types in this mix, from modest 3-4" pods on up to 8", & even 11" claimed.  Some are thin narrow pods, some are thick meaty types.  Some are flat podded, some are round podded.  Most are green, but there are a few purple podded varieties, a few yellow podded types, & a few with different colored streaked pods in the mix.  All are advertised to be stringless, tender pods, & prolific producers.

There is quite a lot of variance between the seeds of each variety regarding seed color, size, & shape.  Most generally have a kidney bean shape, but some are almost perfectly round like a small marble.  Even within a single variety, there are large, medium, small, & occasionally odd shaped seeds.

For the more experienced bean growers out there, have you noticed a small bean seed being more desirable in a snap bean due to a longer window for immature picking, or does it not really matter if you pick every 3 days or so?  

If it doesn't matter that much, would it make sense after a few generations to replant the largest seeds in an effort to have a dual purpose crop in one planting?  

Is dry bean size potential dictated by a larger pod size that leaves more room for beans to grow larger inside?

In my head, I'm trying to work out a way to have a wide variety of snap beans (just to keep meals interesting) which seems like an easy enough goal considering what I'm starting with, but also to encourage larger seed reproduction so that the population will drift toward a dual purpose snap/dry bean type to use in baked beans or soup beans.  I believe this is an attainable goal, but am open to hearing the experiences of others.

For those that have experience with bush/pole crosses, how do you like them?  Are they useful for climbing up to 6-foot tall sweet corn stalks without pulling them down?  I think it would be nice to have something that fits this max 6-foot height with earlier bush type production, yet still keeps the pods above the wet ground & weeds.

All great questions, I'd love to hear answers to them as well.

I'm a landrace/grex newbie so I am loving this kind of conversation.

Well, for anyone interested, I went through all of the bean seeds for this mix to see just what I had here.  I'm very heavy on bush type since that's mainly what I could get locally or trade for.  There just don't seem to be as many pole or half-runner varieties out there as there are bush type.  That said, I'm at 35 different varieties or sources for bush snap beans, all tender, stringless pods, and varying shades of green, yellow, and purple.  I've selected a mixture of seed that includes the full range of sizes, but also added in all of the smallest seeds within varieties to see how seed size matters.  I'll direct sow as much as I can manage, then see how things work out.

Update for my records:  

June 12th, I planted 2 plots of maybe 300-400 bush snap beans of many varieties.  These plots consist of primarily white or dark brown seeds that will produce green snap pods.  I had many more seeds than I could plant this year, and have enough original seed remaining to plant again next year to broaden the colors of seed coats, pods, & overall diversity.  These plots are in an average pollinator area, with a high plant density within rows.  It will be difficult to determine if any cross-pollination occurs in future seed, so I'm planning to rely on characteristics/health/production of the mother to choose which seed is saved.

I also sowed all of my pole beans in one high density-high diversity plot.  I didn't count them, but there were likely around 200+ of my previously saved seeds along with some new seed of various strains.  I have more varieties on order, but they'll have to wait until next year when I'm certain, I'll have accumulated more.  I'm sure within the next 2 months my entire plot will be overgrown, but it's a in a high pollinator location, full sun, & very prone to high heat & drought conditions.  Since I've waited so late in the season to plant pole beans, any seed that reaches maturity should be among the earliest/hardiest the plants have to offer.  Due to very high pollinator activity in this plot, I would anticipate more natural crossing in this pole bean mix.