I had better than 50% germination when I tried these in 2006. I used a standard seed starting mix (consisting mostly of fine peat/perlite) and buried the seed lightly. The seed were exposed to a wide day/night temperature fluctuation as they were just outdoors in the open - perhaps that is important. It was mid-summer so day/night temps would have ranged from 76/50 on average with the pots probably heating up more than that. Sowing the seed too close together, or in not enough light, seems likely to lead to problems.

Another thing you could experiment would be natural outdoor cold stratification which seems essential to successfully germinate Nolina parryi (for me anyways).

I had best luck soaking seed in water for 24 hours then store at 40F for 4 weeks.....