Last year my dad grew pole green beans on a trellis. He went to IFA and bought fence posts and fence panels that were 8 feet wide and 16 feet long and had them cut to 4 feet wide and 16 fee long. Then he planted his pole green beans and they grew all the way to the top of his trellis.
In the spring my dad came down to help me set up my trellis. I went to my local IFA store and bought the same fence poles and fence panels that my dad had used in his garden. He also helped my make my square foot box. I have 3 fence posts and two 4 foot wide fence panels that are 16 feet high, and my square foot box is 8 feet long by 2 feet wide.
When you are planting your pole green beans the weather needs to be 60 degrees. I planted my pole green beans about 3 weeks ago, then in UT we got a lot of cold rain weather so it took them a little longer to start to come up. When planting pole green beans you want to space them 4 to 6 inches apart. When I planted mine I spaced my as close together as I could.