My gracimillus plants self-sow every year, and yield a wide variety of seedlings, ranging from identical copies to plants with much wider foliage. Therefore, I'd say you could grow them from seed if you are willing to cull out non-standard seedlings, or don't mind having non-standard plants. If you want standard plants, you'll have to limit your seed starting to individual seeds, so you won't get mixed clumps.

Starting the seeds is easy. Do it outdoors in late spring. Miscanthus requires quite warm temperatures, both soil and air, to germinate. Sow on the surface, and cover with a very thin layer of fine vermiculite. Keep the vermiculite moist.