Thank you Steven - that was quick!
I like the idea of some string near the bottom, as I assume that once they get something to grab on to, they can start to climb amongst themselves on a wigwam!
Your crops sound great, so it's definitely going to be something for this rather odd little bit of ground! It's in fact the old compost heap, so the soil is the best we have anywhere at home, and as the frame is by a busy footpath, I want to at least try and make it look attractive!