I've had pretty good results propagating D. falcatum using 1 or 2 year old culms (you didn't mention how old the culm you have is.) I use single node cuttings cut midway between the nodes. I trim almost all the leaves off each piece, and wet the node with 10% Dip 'n Grow. I bury the nodes in a pot of 90% perlite 10% peat moss, keep them misted and at about 60-75F with some bottom heat. It takes about 3 months to get new growth and roots.