We live in the tropics so our solution may not be your solution. When we needed a trellis to grow our squash, beans and watermelon on we simply cut our lawn. Our lawn in this case being made up of, amongst other things, some rather nice Bamboo. The structure you are looking at has posts that are two meters apart and two meters tall. It also has bamboo nails to hold it all together. I wish I could say it was entirely ‘green’ but it isn’t, we used half a bag of cement and local sand to pour the post holders.
The structure itself will last for about four months. The vegetables and fruit we plan to grow on it will ripen in about three months. Once the vegetables and fruit have been harvested we will simply turn the trellis into compost. So to save ourselves the time and effort needed to dig new holes, line them with rocks and hope that the buk-buk did not find the posts too soon we used cement. It’s a bit of a cheat and a cop out but it is practical and reasonable.