I would go with a fan trellis and reinforce it with rebar at each side. I saw some really big heavy duty fan trellises at Home Hardware, I'm sure other places would have them too. In my opinion a fan trellis shows off a vine much better than a straight one.

Here is my Jackmanii. It is on a wooden fan trellis. I anchored the trellis to the greenhouse with two or three little nails at the top of the fan. We painted the wooden trellis once more with white outdoor paint, after purchasing it, so that it would last a lot longer outside than the paint that was orginally on it.

The Jackmanii was planted in 2001 and this picture was taken July 13, 2007.

{{gwi:698903}}

They are a beautiful clematis and they bloom and bloom and bloom.....

Brenda

I use free standing ones, but the steel types of trellis with pretty good success. Most have straight sides but an arched rounded top. The beauty is that I just carefully poke them into the ground behind the vine, sort of positioning the trellis so that it leans a bit back against the wall of the house (resting, but not attached to the house wall). I thought in a heavy wind they might blow back and forth and continually bang against the wall, but they haven't really done that.

I also have a few smaller (4 feet) cedar trellis that I just dug holes and positioned the "legs" into the ground. I even put rocks in the holes around the "legs" to hold them better than looser soil. Here too, I think it works okay because I don't try to keep the trellises totally vertical, they actually lean back slightly against the house not really noticeable, however, when viewing the trellis from the front and certainly not noticable once the vine fills the trellis).

Glen

Thanks everyone for the idea's.
Sorry, but one more question if you don't mind.
How high do you have your trellis Brenda?
And Glen...that is how I have mine positioned, with the free standing trellis, but it is much too short. My worry was if the wind caught it, but sounds like it won't be an issue? How high is yours? sorry, this question sounds silly, but if I am going to invest in a couple of them, I want to make sure I get one tall enough.
And Northspruce, thanks for the tip on checking out Home Hardware. (was just thinking of the big box stores)
Debbie

My trellis is standing at 71".

Brenda

Thanks Brenda.
I saw really nice $$ iron ones in Home Depot today, but after buying a peony & rose, I checked out the cedar trellis's. After looking them over, heck... even I could make them easily & won't take me long, so bought some cedar and for $15 will make two of them, versus spending $45.
Thanks for the help everyone
Deb

Gorgeous clematis Brenda...
I'm not so sure they would be so hardy here though...
Anyone have one in Zone 1B?

Rob

Hunnerbun grew clematises in Thompson. I don't know the zone of Thompson and I am not sure which clematises she had there...

Brenda

According to other reports Thompson is in Zone 0B.
I think I'm going to try a couple of the hybrid clematis and see how they do. ( The hardier varieties).
I am going to try and start a number of species clematis from seed...

Rob