Answer: Pruning should also be accomplished according to the prescribed guidelines for the plants in question -- the techniques depend on the type of rose and type of clematis you are growing. Be sure the varieties you grow together are compatible in this respect, also.
Both roses and clematis can be successfully grown up into trees and larger shrubs, can be allowed to scramble on the ground, and can be trained onto nearly any structure, from a picket fence to the side of a barn (Hang a sturdy mesh, such as a cattle panel painted the color as the building, and it will "disappear") to a child's swing set to an old tree stump.
For more about growing roses with clematis, see the article "<a href="http://www.garden.org/articles/scripts/articles.taf?id=737">Roses and Clematis</a>."
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