Here is the main way I've grown pole beans for the last thirteen years, I've got a a couple sets of these 8X8-
(frost is heaving them in the ground still, so are crooked for now, I took this pic today)
"I've liked this method because there is almost never any bunching and layering of foliage at the top, the growth stays pretty balanced all the way up. The odd pole bean (especially runner beans) has been really vigorous & does wind at the top, but those are more the exception to the rule than the norm.
But this year my trellis won't fit all the pole beans types, as I'm growing a couple dozen varieties. So I was going to use some of these for the remainder -
This is about the length, probably between 8 and 10 feet -
I thought using these would be more economical than buying 1X2X8's at 2.50 (probably need about 30-35 and cost of lumber has really jumped), but when I started to think about how I could sink them in such a way to be really stable and unlikely to fall over under a load, I began to realise my economical route may be much more problematic and labour intensive. I really wanted to grow the beans on single poles, until it seemed there is not much info on doing that, outside of my much used Samuel Ogden gardening book from 1971.
I had already bought this year some sturdy T posts from Dollarama, of all places, since they were only 4 bucks and that seemed a pretty good deal. I initially thought of using them for my climbing peas, but when this pole bean problem arose I thought maybe using them to support the saplings, as they can be driven in easily and at a pretty good depth into the clay-ish subsoil. I wouldn't need the whole length of the T-posts, half a length would do it. But that is still coming in at about the same price as a 1X2X8. So, my 'economy sapling method' is turning out to be not so economical afterall.
I think if I drove in something next to the sapling, something I could hammer in, and clamp to the sapling, this would work. The question is, what could that be. I'd like to space each single pole about 2 ft apart. Thank goodness its only April and I've got nearly 2 months to figure this out. I just hope that spending all that time to cut down those poles will not have been a waste, and i'll be able to put them to use.