| Q Carol Fighetti, in his article "Un-derstanding Phalaenopsis" in the
Atf2000 issue of Orchids, advises to "avoid urea-based fertilizers." By
contrasta well-known water-soluble plant food contains 13.4 percent of its total nitrogen
content of 19 (70 percent) in the form of urea. I grow in expanded clay pellets. Can you
give me some insight on this? A Today’s prevailing thoughts are that, because urea-form nitrogen requires the action of soil-borne bacteria to convert it to a form useable by the plants, and these bacteria are largely inactive below 60 F (if indeed they are present at all in soilless media), urea is an unsatisfactory source of nitrogen for orchids. Some feel it may even be harmful. However, fertilizer manufacturers tend to prefer urea-based products as they are much more stable than ammoniacal products, as well as cheaper. I have tried to use products that have a better balance between ammoniacal and urea nitrogen (50:50 seems to be good). Growing in expanded clay, as you do, may demand a completely balanced, hydroponic-style fertilizer that incorporates all necessary nutrients. —NedNash. |
Reprinted, with permission, from "Orchids" - The Magazine of the American Orchid Society, Nov. 2000.