For year-round growers who want to give the soil a break and defy seasonal restrictions, hydroponic gardening is a fun and productive enterprise. With roots suspended in nutritive water-based solutions, these plants are as vibrant and robust as those in the back yard. Yet their unique growing environment leads some to believe hydroponic plants must feed on different nutrients.
In truth, flora are flora are flora. Whatever their growing medium, their physiology requires the same basic foods. Ideally, the sources are natural and environmentally safe. With such guidelines followed, green thumbs can review five of the best organic hydroponic nutrients.
Nitrogen is almost always listed first among plant food ingredients. While there are multiple reasons for this, the primary one is that fertilizers contain large amounts of the element. Why? Nitrogen is among the most quickly depleted. Runoff, erosion, leaching and de-nitrification take their toll on its presence in soil-based gardens. This inhibits the production of chlorophyll, which enables plants to utilize solar energy in the photosynthesis process. Moreover, nitrogen combines with other components to form amino acids, vital precursors to protein production.
Although the necessity of nitrogen applies equally to soil and hydroponics, the latter affords conditions that the former does not. And vice versa. In the dirt, crops can absorb nitrogen as either nitrate (NO3) or ammonium (NH4). Because of certain bacteria in soil, NH4—normally toxic to the plant— gets converted into NO3. Not so with hydroponics, where the plants would quickly suffer from rapid ammonia uptake. Accordingly, the best organic hydroponic nutrients are fertilizers where the nitrogen content is predominantly nitrate salt.
Like nitrogen, potassium serves as an agent in the photosynthesis progression. Beyond that, potassium is central to cell wall construction, as well as the generation, movement and storage of carbohydrates. The relative rigidity and flexibility of cells—a major factor in drought survival— also depends on this important nutrient. In many crops, potassium takes credit for increasing yield and improving irrigation efficiency. Boosting plant immunity and fighting off disease round out its beneficial contributions to crop growth.
In land-based gardening and agriculture, organic forms of potassium are sometimes known as potash, a name given because the element was discovered in abundance in a pot of burned wood. For hydroponic gardening, a common recourse is organic fish feed but this potassium source proves to be insufficient for fish, let alone for plants. However, adding kelp meal concentrate to the root solution bumps up potassium percentages noticeably. This dried-seaweed additive demonstrates positive results with lettuce and potatoes, in particular. It is among the best organic hydroponic nutrients.
Another star in the category of best organic hydroponic nutrients is phosphorous. Acting as the fuel that makes a plant run, phosphorous composes the chemical bonds that receive the energy produced by photosynthesis. When the bonds break, that energy is used for life-sustaining chemical reactions within the organism. Thus, healthy growth requires a wealth of phosphorous. Unfortunately for many gardens, phosphorous is known better by its lack than by abundance. Plants often fall short of their potential due to a poverty of this crucial element.
Here is where hydroponic gardening has a distinct advantage over soil. The minerals in the ground that otherwise obstruct or absorb phosphorous in fertilizer solutions are absent in water-based plant-raising. At the same time, ensuring adequate presence of this nutrient should not be left to chance. In nature, mycorrhizal fungi equip roots to better receive phosphorous. It can do likewise in a hydroponic setting and makes a positive contribution to any solution that feeds the root systems.
People know that the mineral calcium is essential for strong bones and teeth. Adequate calcium absorption wards off osteoporosis. This holds true also for the “skeleton” of plants, i.e. the cell walls. Healthy cell walls regulate water inflow and undergird cell growth, which is stunted without satisfactory calcium presence. There are tell-tale signs of calcium deficiency in flowers, herbs and vegetables: brown spotting on leaves; blossom end rot in peppers and tomatoes; black heart in celery; and internal tip burn on cabbages.
One of the best organic hydroponic nutrients, it suffers when humidity is too high or too low. When too high, humidity slows the flow of air across the foliage and arrest the entry of calcium into new cells. On the other hand, low humidity will raise water stress in the plant, also affecting calcium dispersion. An indoor hydroponic system allows, of course, for greater climate control. Yet other factors are at play regarding calcium. Organic materials like coconut fibers, often used in hydroponics, also inhibit calcium uptake.
While it achieves its purposes in small quantities, sulfur is nevertheless an indispensible element in the category of best organic hydroponic nutrients. Key to its fundamental nature is its capacity to form enzymes and proteins that strengthen plants structurally and foster root growth. Sulfur also improves the performance of phosphorous.
Deficiency shows up in thin, weak stems, drab color and irregular leaf emergence. Important to note is that sulfur is not water soluble in its pure form. In order to utilize sulfur for hydroponic use, a gardener needs oxidized sulfur, known commonly as sulfate. Gypsum is a good organic source of sulfate, though its solubility requires time and effort. In addition, gypsum’s calcium content will sometimes stifle sulfur uptake.
Since plants generally require the same nutrition whether they grow in soil or in water, the decision gardeners must make is over which nutrients do best in which medium. Understanding the optimal fertilizer for one plant may or may not take into account the issue of solubility.
Therefore, hydroponic practitioners must weigh the benefit to the crop against the efficacy in a solution. The good news is that there are numerous sources of each nutrient so creating the optimal solution is not as daunting as it may appear at first. Hearty vegetables and ornamentals grow from just such experimentation.