Answer: According to Michael Dirr's Manual of Woody Landscape Plants, softwood cuttings taken from younger trees (2 to 3 years old) root best; he suggests treating with rooting hormone (1000 ppm IBA-quick dip) and placing in sand under mist. Or, you could take hardwood cuttings in June/July (at that season he used 10,000 ppm IBA). He notes specifically that cuttings taken from older trees are very difficult to root.
For general directions on taking and rooting cuttings, you may want to look at the following web site.
Best of luck with your project!
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