Trying to get my well-started (ok, dying for room, the poor things!) pole bean plants in and going but still can't decide the proper spacing for them to be able to gain the best root volume/health to grow lush and dense (they're for shade, the beans are a nice benefit of the shade).

As these are quite able to grow to 8-15 feet tall and are showing branching tendencies already, I'm thinking that my 5 gallon-ish square bucket planters may not do the trick as well as I'd hoped.

Does anyone here know just how much rootspace pole beans need to grow like mad, as opposed to putting out beans like mad?

Thanks to all!