One way to promote root development in cuttings is to use a commercial rooting hormone, usually in powder form. I have found a DIY method using the sap leached from willow switches into water. I have not used the method myself, but it may be worth exploring and testing. The blog article suggests that soaking seed in the solution may also improve germination rates. When commercial products may be unavailable, this method may have some potential. http://www.pioneerliving.net/apps/blog/show/6244703-rooting-hormone-and-plant-growth
Supposedly dipping the ends in cinnamon powder will also act as a rooting hormone. I haven't tried it tho.
