I have, planted in a box, some peas (not sure of scientific name, or hybrid, but standard shucking spring peas). I am having difficulty training them to climb up the apparatus built for them. It is fairly simple, it is just cotton cooking twine between pieces of wood. But the runners do not seem to be grasping on to them to pull up. I have repeatedly attempted to train by either laying them across the strings, or actually gently wrapping around, but they do not seem to be taking. will peas not climb the cotton trelis? Is it that, or do I have exceptionally stubborn peas? thank you in advance.