Answer: Organic fertilizers such as guano and cow manure must be decomposed by bacteria before the nutrients they contain can be absorbed by plants. Decomposition does not occur readily in the type of potting materials used for growing orchids, therefore organic fertilizers are not suited for orchids. Also, unprocessed organic fertilizers can host diseases that will affect our plants. For these reasons, we use, as our basic fertilizers, inorganic fertilizers.
I'd recommend using a liquid fertilizer such as Shultz's or Peter's for your orchids. They contain all the necessary nutrients and since they're in liquid form, there's no residue left on the top of the potting soil as there would be with granular or time release fertilizers.
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