Plants are critical in our daily lives and many people take them for granted. We feed ourselves with plants, we feed our food with plants, we breath the oxygen from plants, they “breath” our carbon dioxide, they keep the soil strong, and they do a lot more than what I can fit in this article. Bottom line: they are critical to our survival. Shouldn’t we respect plants as much we respect ourselves? Plants deserve to be just as healthy as we do, but they need some help from us!
When someone hears the term “plant health” the most common association that comes to mind is “fertilizer.” Fertilizer provides essential nutrition to plants and growers must decide what types to use in order to maximize yield and salability, which are a direct result of optimum plant health. The aspect of health that is most often overlooked is pH (a.k.a. the potential of hydrogen.)
The pH measures the acidity or alkalinity of a liquid solution; in this case, the nutrient solution. If the solution is acidic, it has a lower pH and lots of hydrogen ions (H+) floating around. In a basic solution, there are lots of hydroxyl ions (OH-) floating around. Acid or base just describes which ion has a higher concentration in the solution. Water, which is considered neutral with a pH of 7.0, has equal amounts of hydrogen and hydroxyl ions. As far as plant health is concerned, these ions control what nutrients are still dissolved in the solution and which nutrients plant roots can absorb. Take a look at the chart below:
These are the essential nutrients; every one of these ions is required by plants in order for them to grow. They are absorbed in varying amounts depending on availability and the crop being grown. The chart visually expresses how pH affects the availability of each ion in the nutrient solution. The blue region is the ideal pH range for a hydroponic nutrient solution, but some fluctuations in pH are expected and not really a big deal so long as it is monitored and corrected on a regular basis. For most common greenhouse crops like tomatoes and lettuce, keep the pH just below 6.0 which is ideal to maximize uptake of every nutrient. Allowing the pH to fluctuate too high or low can result in some ions precipitating out of solution and becoming unavailable to the crop. For example, at a pH of 7.5, manganese, boron, and phosphorous are virtually unavailable to the crops which will lead to deficiencies if left unchecked.
From this point forward, pH will be an acronym for “plant Health.” This is one of the most important aspects of growing plants and cannot be overlooked without expecting an unhealthy crop and poor marketability. Since hydroponic growing systems often involve plant roots coming in contact with the nutrient solution regularly, if not constantly, the potential of hydrogen must be corrected to the appropriate range to maintain optimum “pH.” If we want to be healthy by maximizing our intake of nutrient-rich foods, we must make sure crops are rich in nutrients by maximizing their uptake.