How to Prune open-flowered clematis?
See clematis pruning: group two

open-flowered clematis · Clematis patens
Plant in moisture-retentive, well-drained soil, with the roots and base of the plant kept cool and shaded by other plants or a layer of pebbles at the base. Plant with the crown 5-8cm deep to encourage new shoots to grow from below ground level. Ideal for a trellis or garden obelisk. See clematis cultivation
See clematis pruning: group two