Here is Scott and Bruce Bayer in Bruce's "screen-house".  The Haworthias we saw today were Bruce's research material as his plants form an important research tool as he works on the relationships between  and within species.  All that being said, his plants were wonderfully grown and a beauty to behold.  Like some other growers we visited, Bruce prefers to grow his Haworthias in the local red dirt, the same stuff the Haworthias themselves prefer in the wild.