In general, you sow on the surface, and keep the medium moist until germination occurs.

With 'Eaton Canyon' it doesn't matter, because it seldom produces viable seed. The Miscanthus will depend on the cultivar. Variegated, dwarf and other special cultivars of Miscanthus generally don't come true from seed. If they germinate at all, you'll likely end up with just the species, green with a white mid-vein.