Ha, I thought Dr. Motes is surely no English major, and he sure didn't pay anyone to edit his books. There are spelling and grammatical errors everywhere in both his books. But he does have a PhD in something, wait! Hoo Boy! Turns out he IS an English major, as he was an assistant professor of English at Wright State University . . . who knew?? So, at least he is a gardener, but not a scientist.
At least we know he knows how to grow great orchids.
Anyway, here are the pertinent passages:
"Two facts stand out from this study: orchids need less phosphorus than previously thought and they need more magnesium than they usually get. This new approach to orchid nutrition has particular cogency for us in South Florida where our ground water sometimes contains phosphorus (particularly on the West Coast) and almost without exception, is highly alkaline. The high pH of our ground water in combination with phosphorus in fertilizer binds up most of the metallic trace elements, including magnesium."
The study he refers to is the research begun @ 2003 at Michigan State University to develop better formulations of fertilizer, specifically for orchids. He also says later "Mature plants in general require less phosphorus because it is an element plants tend to conserve, and transport from older tissue to newer growth." So his advice is to only use "bloom booster" fert that is high in phosphorus for a couple of feedings in the spring when plants are growing roots and getting ready to develop blooms.
Later on, in the Vanda book he says he also 'shocks' some of his Vandas with a dose of bloom booster in the fall around the time the first cold front is forecast, because Vandas often put on blooms in response to the temperature change.
