The only ones I can allow to grow large are two rare ones and one that was rarely seen for sell when I purchased her five years ago, but now is more often found. I don't know what I will do with them now that they have grown large. They are more slow-growing than the bifurcatum (thank goodness) and won't get gigantic like the bifurcatum, but they are now getting pretty doggone large considering they have to be grown indoors during the fall and winter months. I have the P. Mickey's Rainbow and Mauna Loa which are really rare ones. Though I purchased the "French/Silver Staghorn", P. veitchii 'lemoinei' at the same time, I see it more readily for sale now.
By the way, Elaine, I no longer purchase or grow the "standard" P. bifurcatum. I now only purchase and sell the P. bifurcatum 'Netherlands'. This sub-variety grows more slowly and doesn't get as large as the standard. In my opinion, the 'Netherlands' has nicer shaped fronds.