I would imagine that leaf blowers operate at a much lower density of grass, in an open area where there's nothing for a grass blade to stick on.

First thing I thought about was fluidizing the grass via forced air. Plenty of bulky stuff is handled fluidized. One good example is the hydraulic french fry maker where potatoes are fluidized using water and pushed through a slicing grate using the pressure and velocity of the flow. The water carries the french fries out of the other side just as easily.

You can probably blow it in just fine. The problem is really getting bulk materials out of hoppers. A whole world of research and engineering unto itself.

Start with a simple question like: what kind of model do you use with bulk materials. Obviously it's not a liquid, but as a solid it has tons of weird properties- No tensile strength at all. Strength depends on history of compaction. The list goes on...