In 2006, I visited the botanical garden and picked up a Melocactus glaucesens from the gift shop. Now, many years later, it's fully mature and for several years has been producing what appears to be viable fruit. As I found out a rare species (and it has proven to be a very nice houseplant, too) I would love to try growing it myself. Unfortunately, I've been unable to find anything but general advice on how to propagate Melocactus, and some of it is conflicting. I would love some species-specific advice since it does seem to vary from species to species, but due to the rarity of M. glaucescens I cannot find any guides to growing it. Since it came from NYBG, I'm sure you can provide some information!
Melocactus glaucescens is best propagated from seed, although the young seedlings of M. glaucescens are very small and can be trickly to cultivate for the first year or so.....an email is being sent with the remaining information along with scanned pages of information to complete the propagation techniques.