I've used this, along with many local grasses for aging. The trick IMHO is to harvest them after they drop their seed, so you're harvesting the cellulose shell that makes up the stem. And let it dry out properly to a low moisture level. Works great!
You don't even need to make it into a mat, you can just rest the cheese on top and flip repeatedly. If you have fines, they tend to stick to the cheese. Easiest is to pick out the long stems and use those.
If you're aging in small quantities, you can also bury the cheese inside. Put a layer on the bottom, and then put a loose layer on top, and then check back in a few weeks. Makes for a lovely approach to aging lactic cheeses, and gives a great taste note, especially when you're using fresh cut stems.