Posted: 28/05/2015 at 16:41
I imagine it's the low temperatures - from what I can find out their ideal growing temperature is between 25 - 35C
I've not grown them - it's tough enough growing runners and french beans in the UK and occasionally I grow Borlotti beans.
I think Yardlong beans are a challenge too far for me
I wonder if they'd be happy in a polytunnel - has anyone tried?