We, in the orchid world, are second only to cannabis growers in the search for that “holy grail” product that will make our plants grow better. As my professional career was in the chemical industry, that bias may make me one of the best (worst?) examples of that. We experiment with fertilizer formulas, stimulants, inoculants, grain alcohol, worm teas – anything – that anyone, anywhere, has even suggested might be beneficial, as a way to rev up our plants. What we often fail to recognize however, is that all those things, as beneficial as they may be, are merely supplements to a far more basic, essential parameter – water.
Water is to a plant, as air is to a car engine. When we “step on the gas”, we aren’t controlling the fuel pump, but are actually increasing the flow of air into the engine so that more fuel can be burned. Applying more fuel without that extra air is “flooding” the engine, which is counterproductive.
During photosynthesis, water is broken down into hydrogen and oxygen. There is an enzyme within the plant that can either bind to that oxygen, or to carbon dioxide that has been taken in through leaf stomata. If the enzyme binds the CO2, then carbon is affixed, and plant growth occurs. If that enzyme binds to oxygen however, no carbon is assimilated, and the binding energy used is lost, which in extreme cases, can lead to a significant decrease in plant growth. That’s where the roots and water supply come in.
If the roots of the plant are unstressed and the water supply is substantial, hormonal signals are sent from the roots to the leaves, and the stomata open, allowing the plant to expel oxygen accumulated during photosynthesis, and to absorb atmospheric carbon dioxide. As the oxygen concentration within the leaf decreases and CO2 increases, the probability of the enzyme binding with CO2 increases, so carbon is affixed at a greater rate, and the plant grows. If the water supply is insufficient, that signal isn’t sent, the stomata stay closed, less carbon is affixed, and growth is reduced.
To provide some sense of scale, consider that in general, plants are 85% water, 14% carbon, and that remaining 1% is everything else, including all of the fertilizer minerals. Using those percentages and some conversion chemistry, in order for a plant to reach a weight of one pound, it will need to absorb and process about 25 gallons of water, and less than a teaspoon of fertilizer.
Consider what this means to our selection of potting media: If we use media that stay open and airy, even when saturated, then we have no fear of root suffocation, death, and rot, so we can be very generous with our watering regimen, “opening up the throttle” on plant growth. If on the other hand, we use a potting medium that can be waterlogged for a time, then we must wait for it to dry out before we water again, and during that time, when the available water supply is limited, we are actually slowing down the growth of our plants. Not only that, but if our potting medium and watering habits conspire to damage the root system, then the ability of the plant to take in water for growth is also stifled.
Going back to my own chemical industry “roots” for a moment, root growth stimulants, like KelpMax, can still play a significant role, as a bigger, more developed root system can absorb more water than a less-developed one – sort-of like upgrading from a two-, to a four-barrel carburetor on your car.