My husband made mine so I'm no help.

Try pounding rebar into the ground. We have used 3 rebars in a triangle and tied together near the top with one of those heavy-duty plastic ties whose name escapes me now. It's as cheap as you can get and gets covered by the clem.

I have not built one, but various threads on trellises made from cattle panels have caught my attention this past winter.

Here is a link that might be useful: threads on cattle panel trellises

Most larger trellises are custom built, by the homeowner/friend or a contractor. One of the easiest is to purchase a prefab sheet of lattice (4'x8', sometimes 2'x8') and frame it out. Or use bamboo poles - available at most larger garden centers in a range of heights - tied together to form a teepee or obelisk. The cheapest large 'trellis' for a clematis is training them to grow up a tree or into a large shrub. Or along an existing fence.

Since trellises tend to become permanent garden additions and are often quite visible, investing a bit of cash to create an attractive and longlasting trellis may be well worth it.

I've toured a garden that did cattle panel arches covered with Clemmies and it was spectacular.

I'll never use cedar lattice again. They don't climb it well for me and I'm forever trying to guide them through and breaking them off. This after DH made me free standing trellises, fences and topped our solid cedar fence with lattice....

I'll have him frame out cattle panels from now on.

This is one they had just set up so I took a picture as you could see the arch. I've been reading the links above and the veggie folks anchor these with cement and 4 x 4's or rebar but this garden had about eight of them and I didn't see anything like that. They did sway some when you touched them but some had been there for years given the size of the Clematis. Most weren't blooming yet so no pictures of the covered ones.

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This lady covered her entire cedar fence with wire livestock fencing and there are close to 100 Clematis surrounding her yard.

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Here are some nicely framed at the Rogerson Clematis Collection in Lake Oswego OR

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