We have created several arbours from material such as old cedar rail fencing and salvaged hydro poles.

In the case of the rail fencing, cut metal fence poles in half and driven one piece into the ground at each corner with abut 2 feet or more above ground. The cedar rail corner posts are wired to those. This arbour has been in place for 7 years and has supported 2 honeysuckle vines.

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The largest arbour is made from hydro posts, is about 10 feet tall and the posts are cemented 3 feet into the ground. We bought lumber to make the cross pieces but the 1x1's were salvaged from a friends garage after he built a deck.
This arbour is so sturdy it would support anything you wanted to put on it! I have a large sweet autumn clematis. I wrapped the post closely with chicken wire to give the tendrils something to grab onto.

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Try 3 pieces of 1/2" x 10' rebar to make a tripod. Shove them into the ground about a foot and a half, tie the top together with a pipe clamp or baling wire, and plant your cardinal vine. I'm using these tripods to support roses, and they work great. Cheap, and effective.

You can see the tripods along the fence in these photos of the garden when I first put it in last fall. I hadn't tied some of the tops together yet, but I think you can get the idea.
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Hope this helps,
Connie

We bought our first arbor, but plan on building one here in the near future ourselves. This site has some free arbor plans to look through. Might give you some good ideas!

Some pics of one I built out of cedar.

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Great ideas in this thread! Wyndyacre, what a nice sturdy arbor...DH and I were talking about grapes recently, and how they needed a strong support. Looks like that one would do it! Good idea about wrapping the post closely with chickenwire too.

Stressbaby, did you make those lovely arches out of separate cedar pieces joined together? Or, did you somehow form the wood into that arched shape?
Sheri

Each arch is actually a pair of arches, 2 x 1" cedar. Each 1" wide portion of the pair is about 4 section butt-joined with biscuits. The joints of each pair are offset for strength. Each pair is topped with 1/4" wide cedar strip.

Thanks Stressbaby. I showed DH your pics, and he said he'd get right on it (LOL). Our style of carpentry is more like...hold Piece A to Biece B and insert screw. ;-)

Very nice!

What a lovely arbor Stressbaby. I'd like to build posts similar to the ones in your arbor to replace front porch posts at my home. Did you build them as well?