Try air-layering. You can look it up, but I'll summarize the procedure.
1) select a young branch that is just getting woody, but is not older than 1 year or so.
2) take a knife and make a slit parallel with the length of the twig, but don't completely sever the branch.
3) dust some rooting hormone in the center of the cut.
4) stick a wooden match or something about that size in the slit to keep it from closing and healing.
5) get a handful of damp (soaked then squeezed out) sphagnum moss and bunch it all around the cut, to about the size of two hands clasped around it.
6) cover in clear plastic-wrap and tie the ends with string to keep it closed.
7) take a paper bag and wrap that over the plastic to keep out sunlight, preventing the plastic from acting like a greenhouse and cooking the twig.
8) wait.....might be a few weeks, might be a few months, but eventually you'll start seeing tiny white roots forming in the sphagnum moss under the paper bag through the plastic.
9) when you see strong rooting, completely sever the twig and plant it in a pot to grow on before planting in the garden.