Thanks for writing. Take cuttings that are 3-4 inches long from the tips of the plant's shoots in late summer to fall. Treat the cut ends with a little rooting hormone to help them take more easily, then pot them up in moist sand, perlite, or vermiculite. Keep them humid and out of direct sun and in 6 to 8 weeks they should root.
You can also take cuttings from autumn to January or so; pot them up in moist sand and keep them in a cool, humid spot. They should root in 3 to 4 months.
---Justin, Senior Garden Editor, BHG.com