This is a C&P from :
Amazoy, the first cultivar to be released by the US Department of Agriculture is still the superior standard. Vegetatively propagated zoysia grass will provide a higher quality lawn than any of the seeded varieties.Historically, it has been extremely difficult to create a fine zoysia grass lawn from seed. It is hard to grow because only a small percentage of zoysia seed will successfully germinate and it is extremely sensitive to light. Consequently, areas to be established by seed need to be covered with erosion cloth to reduce surface disruption caused by rain or irrigation and irrigation is most important. Zoysia seed requires copious and frequent watering until the lawn is completely established. That's a lot of water!All the zoysia grass seed we have seen and tested resulted in lower quality turf stands. Seeded varieties produce medium to coarse textured turf. Overall growth is somewhat uneven and tends to form mounds.Winter-hardy zoysia grass seed does not yet exist. Attempts to produce zoysia grass seed that spreads quickly and stays green longer do so by sacrificing winter hardiness. What good is a seeded zoysia grass lawn if the first cold frost will wipe it out?
Oh well, I guess I'll still try to grow them from seed :(