These, together with magnesium, calcium and sulfur, constitute some of the essential inorganic or macronutrients that all green plants require for continuing healthy growth and flowering. In addition, other chemical elements are needed by plants, but in very small amounts. These are called micronutrients, or often, trace elements. Among them are iron, chlorine, copper, manganese and zinc. Many commercially available fertilizers contain micronutrients as well as macronutrients.
Plants only take up, or absorb, chemical salts dissolved in water, mostly through their roots.
Orchids are no exception. These mineral-salt solutions are distributed throughout the plant by the conducting chemicals. The functions of the chemical elements in these mineral salts, or inorganic nutrients, are fairly well known. Green plants possess the amazing ability to manufacture their own food through the process of photosynthesis. And it is this process upon which the entire world of living creatures depends for its own food, either directly by eating plants, or indirectly, by feeding on other organisms that have fed on green plants.