Many Croton varieties have been lost to the trade for several reasons; many more have become rare, and others are just harder to find because they are not as widely grown. Coincidentally, many desirable cultivars sought by croton lovers today are large leafed varieties, which are not commonly cultivated or easily located on the commercial wholesale market. Cultivars with the largest leaves can be slow growing and poorly branching. Unfortunately they are not good candidates for tissue culturing in its present form. Propagation is primarily by tip cuttings or air layering.
Most wholesale nurseries work on volume and low production costs because our mass merchandising system demands large volume at low cost for sales through large mass merchandisers.
Large scale croton propagation—when both time and space are at a premium—relies predominantly on mist house rooted tip cuttings. The additional space and/or time required to cultivate larger leafed croton varieties is neither an available nor an affordable option. For instance, ten Mammie or Gold Dust can be produced via tip cuttings in the same space it might take to grow one Thomas Edison or Jungle Queen croton.
While air-layering is too slow and tedious for most commercial nurseries, old-time and rare crotons are largely dependent on the dedication of devoted croton lovers for their propagation.
We owe a debt of gratitude to all those who, long before we, discovered and extolled the beauty of the Codiaeum variegatum. In particular we would like to acknowledge Eugene Andre,
Dr. B. Frank Brown, Bob Alonzo, Jeff Searle, Jesse Durko, Jim & Judy Glock, Phil Stager, Jose Lopez, Cleofar Millare, and more recently: Dypsisdean, and countless others who continue to dedicate themselves to its preservation, conservation and study. https://www.palmpedia.net/wiki/CROTON_ONLINE_REFERENCE
Air-layering is a reliable process for propagating crotons, and one which ardent croton lovers soon come to appreciate. It’s also a handy technique to know as it can be practiced on all woody shrubs, from hibiscus to roses.