Forget 6 inch cuttings, for bigger shrubs use bigger cuttings. Giant cuttings of 18-36 inches may be worthwhile on the following:- Cistus, Euonymous, Hebe, Leycesteria, Weigelia, Pyracantha or Kerria japonica. I have a friend who excels with Roses taken this way.
Also read Gardeners tips Taking cuttings for beginners

Proceedure for Cuttings

• Water the host plant well the evening before taking cuttings.
• Take cutting early in the day, keep out of the sun and spray with water to minimise wilting.
• Select a shoot with plenty of new growth. Cut it off cleanly at the base where it comes from a branch or cut below a swelling leaf node instead.
• Remove any flowers, lower leaves and soft tips by pinching out
• If the cutting has a woody bark remove a sliver an inch long to aid rooting.
• Have available one litre pots full of a free draining mix of grit and multipurpose compost.
• Dip the end of the cutting in fresh hormone rooting compound, such as Murphy’s, plant and water in
• Place in a humid environment eg. a plastic bag over the pot supported by canes, so leaves don’t touch the sides, and tied with a rubber band.
• Keep in a shady spot removing dead leaves regularly.
• In about 5-6 weeks, when rooted, acclimatise to outside conditions and overwinter in a sheltered spot
• Plant out in March

Climber Cutting Tips

• For many climbers it is worth burying the tip as well as the heel in the compost making an arch.
• Clematis montana throws up more side shoots when treated this way.
• Lonicera honeysuckles react well to this arching technique and may root at both ends
• The best cuttings are taken from growth which is just hardeneing.
• Take extra cuttings in case of failures
• Many climbing roses will grow as climbers from the new root stock. Those that were grafted onto climbing stock may not have the same characteristics.

credit Mullenkedheim CC BY-NC-SA 2.0