A well-clothed pergola, obelisk or arch can be a magnificent feature in the garden. When choosing roses to cover these structures, it is important to consider their size. Your chosen roses must be tall and vigorous enough to clothe the structure but not so tall and vigorous that they overwhelm it. Ramblers are a good choice because their reasonably lax growth and long stems, make them easy to tie into the structure. Pergolas and arches require larger ramblers and climbers than obelisks, which, on average, only need roses of about 6 to 8 feet. Repeat-flowering varieties are the ideal choice, or, alternatively, roses that bear attractive hips in the Fall. If your heart is set on a once-flowering variety, you may like to consider planting a late summer-flowering clematis alongside the rose, as this will extend the flowering season.