I believe you can though have never tried this species. Its sub-shrubby so I would say now is a good bet. Take small none flowering shoots about 4-6in long from near the base of the plant if available. These will probably root better than from the ends of larger stems (certainly not the stems that terminate in a flower spike). Put in a very gritty (half sharp sand/half seed compost) mix and keep just damp with a poly bag over the top. I suspect that a little bottom heat will speed up rooting with this one?

Someone with more experience of this magnificent species should help further though.