Hydroponic Plant Nutrients
In addition to the major plant nutrients most gardeners are familiar with, Nitrogen (N), Phosphorous (P), and Potassium (K), aka N-P-K, plants grown using hydroponic methods must also be supplied the minor and trace elements necessary to provide for healthy, productive plant growth. These include, but are not necessarily limited to, Calcium (Ca), Magnesium (Mg), Sulfur (S), Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn), Zinc (Zn), and Molybdenum (Mo).
While many hydroponic and soilless culture purists maintain that since the hydroponic technique is primarily about controlling the inputs, organics should play no part in hydroponics. However, a growing movement of organic enthusiasts, as well the increasing popularity of aquaponics, wherein farmed fish waste is recycled as nutrient for growing plants in the same recirculating system, have more or less proven that organic hydroponic cultivation can be successful, even though a great measure of control is lost in the process.
The raw elemental nutrient salts are available to growers who wish to blend their own custom nutrient formulas, along with the tools necessary to determine the necessary mixing ratios (HydroBuddy; HydroCal). However, the convenience of premixed nutrient concentrates drives a huge market with scores of options for hobby growers.
Hydroponic plant nutrients are available premixed either dry or in concentrated liquid form, in numerous formulations for both hobby and commercial growers.
Granular | Dry
By far the most economical way to purchase hydroponic plant nutrients, as granular nutrients are merely blends of the same dry mineral nutrient components that are used to manufacture liquid hydroponic concentrates. This high level of concentration makes dry hydroponic nutrient blends and components ideal for larger commercial hydroponic greenhouse facilities where nutrient reservoirs can have thousands of gallons of capacity.
For commercial growers, most granular nutrient manufacturers offer custom formulations for different commercial greenhouse crops, including herbs, strawberries, cucumbers, lettuce, peppers, tomatoes, and others. Also available are the raw mineral nutrient ingredients including boric acid, calcium nitrate, copper sulfate, iron chelate, magnesium sulfate, manganese sulfate, monopotassium phosphate, potassium nitrate, potassium sulfate, sodium molybdate, and zinc sulfate. Dry, granular mineral elements are the foundation for all but organic liquid hydroponic nutrient concentrates.
Single-Part Liquid Concentrates
Single part hydroponic plant nutrients are formulated to contain all of the macro, minor, and trace elements to support healthy plant growth in a single bottle. They are created by mixing dry mineral powders into water to form a “liquid concentrate”, wherein a smaller amount of the concentrate is blended with water to create a nutrient solution in amounts that are ideal for the particular crop being grown. Different formulations target specific stages of growth such as Grow for vegetative nutrition, or Bloom for the fruiting and flowering stages of plant growth. All-Purpose varieties are often available as well. Often, single part hydroponic nutrients are formulated with less than optimal amounts of calcium (Ca) and/or sulfate (S), as higher concentrations of these elements, especially in combination with phosphorus, tend to solidify and particulate out of the solution, substantially reducing their immediate availability to the plant. Depending on crop requirements, to offset this phenomenon, many users of single part nutrient solutions are forced to amend their solution with calcium or other minor element supplements to achieve the desired results.
Some nutrient solution companies are creating new single-part formulations which claim to overcome these deficiencies, however, it is of utmost importance to always shake hydroponic plant nutrients in their original bottles extremely well prior to mixing into a nutrient solution.
Two-Part Liquid ConcentratesIn order for the manufacturers of liquid hydroponic plant nutrients to provide optimal levels of calcium and/or sulfates, multi-part nutrient concentrates were developed so that the incompatible nutrient components could remain separated, and therefore more immediately available when diluted individually into the nutrient solution. Typically labelled as a Part A and Part B, these individual concentrates are mixed into a nutrient reservoir separately in a proper order to fully blend the components together in a way that doesn’t cause the incompatible nutrient components to solidify and precipitate out of the solution.
Typically, the calcium component will be found in a two-part solution’s Part A, while the sulfate is kept separate in the “Part B” component of the formulation. Two-part nutrient solutions will often offer a phosphorus and potassium boost supplement which is used for plants with more aggressive growth habits.
Three-Part Liquid ConcentratesThree-part hydroponic plant nutrients are divided into multiple parts for the same primary reasons as two-part concentrates, the primary advantage of which is the increased flexibility in creating custom nutrient ratios by the end user. Whereby a typical 2-part nutrient is meant to be used in the NPK ratios it was designed to possess, a 3-part nutrient allows the grower to modify the respective NPK ratios to suit their personal tastes or requirements.
More often than not, 3-part liquid hydroponic nutrients are different colors, however, the coloring has no bearing on the nutrient value and is created by adding small amounts of coloring agents to the concentrate. The coloring is generally added as an aid to identification by the end user.
Organic Hydroponic NutrientsThe inherent problem with “organic” hydroponic plant nutrients lies in the fact that only non-mineral nutrient sources can be utilized. Since most organic fertilizers must break down into a usable form for the plants, enzymes or bacteria must be incorporated into the nutrient solution that will break down the organic materials so that their nutrient value can be released for uptake by the plant roots. However, many hobby hydroponic growers have had success growing crops utilizing compost teas, and research has led to new OMRI Listed organic hydroponic nutrient products which are due to hit the market in the very near future.
Aquaculture is a type of organic hydroponic crop production that utilizes a closed loop, recirculating system to raise edible fish while growing plants with the water they are raised in. The waste from the fish provides the nutrients for the plants growing in hydroponic trays or gutters that are placed above the fish tanks, which also serve as the nutrient reservoir for the growing system.