Yes, I dug 20" post holes for my poles. If your poles aren't long enough, you could pound t-bar fence posts into the ground. If they're not secure in the ground or attached to something that is, they WILL blow over. I used Eastern Red Cedar (juniperus virginiana). You need cedar, locust or some other wood that termites won't eat, else your trellis will fall over at the ground at the end of the first summer (happened to me). You can get chemicals to treat ordinary woods if you want to try that, or use rebar or metal fence posts to secure them above the ground.

Kirk LOVE your arbor. You did a fantastic job on it and the fence as well. Great Garden Art. I have collected cedar trees to do an arbor too. I would love to see a close up pic of how you did the sides. I'm just flying by the seat of my pants on this project. Thank you for the kind words on my rocking chair. I got the idea from my cousin. She has had one for years...we just visited her over Easter and I'm sending a picture of what is left of her chair. I love it! this was it before it fell totally apart http://family.webshots.com/photo/2876392790076687016cvkyTu Enjoy!

To compound your dilemna,I would suggest you look on the web at a place called Gardenvines.com or Brushwood Nursery. They will give you a vast choice and you will have to chose, after reading seperately about each one. I am a customer of theirs but in no way commercially involved with them. I have roses, since my wife loves them, but no climbers. I grow the following vines: Honeysuckles of 6 kinds. 3 that smell good but do not bloom all summer and 3 odorless but blooming on and off April to November. 4 Jasmine relatives that have no odor and bloom briefly Akebia quinata,which can be too vigorous. At least 5 kinds of Clematis. Only Polish Spirit seems to bloom for a long time for me. Crossvine, with little success. Trumpetvine, too big and rampant for your purpose. Gloryvine, too big also. If I were to grow a climbing rose, I would like climbing Joseph's Coat, but there are many and the newer ones might be more disease resistant. If you fail with a plant, ask a successful neighbor about his or hers. They might be like me and have too much to say and be anxious to share info.

Would sistering, or using a manufactured beam (the OSB fin, wood top/bottom I-beam sort of thing) be better? Unfortunately, the question is, how the op will pass the pipes through. I suspect they will have to cut a section from the pipes, slip sistering joists in, re-glue pipes. Cutting a wedge out of new joist would weaken them too much - rinse, repeat, unless they were perhaps tripled, with the cutout opposed. (one top, one bottom?) I think the length of the sister material will have a large bearing on it (pardon the pun) - the longer the better. To some extent I guess the 'sistering' effect works only to the next support point, am I right? Maybe if they are VERY well attached to each other, it would carry the load further? I don't know if this would raise more issues since it involves more penetration of the joist, but I'd use very snug-fitting bolts at the ends of the sisters, and perhaps one each side of the weakened section. When drilling for alarm wires, and we sometimes use a very small bit (3/8") I was told, never drill a manufactured beam, but the OSB I-beam type was ok, but not within 20" of the main support point. Often in practice, though, I would drill next to where the electricians went - since they always came in first, I guess the strategy was "I assumed it was ok there because the sparkies did it ;)