How Hydroponics Work


Hydroponic gardening offers several advantages over soil gardening. The ability to produce higher yields in a smaller space makes hydroponic gardening ideal for those with little to no yard space. The ability to grow indoors makes a year-round harvest possible anywhere. Plants grown hydroponically receive all of their nutrient needs and none of the toxins that may be present in the area, producing fruit and vegetables that are nutritionally superior to those grown on depleted soils. Growing without soil prevents soil-borne disease and pest problems.


Hydroponically grown plants must have all their water and nutrition needs supplied by the nutrient solution. A chemical or organic nutrient mix is combined with distilled water to feed the plants. The nutrient solution is carefully adjusted for pH and the roots are either immersed in the solution or periodically coated or sprayed with the nutrients. The plant extracts the water and nutrients it needs, altering the composition of the nutrient solution. As nutrients are depleted, the pH may need to be adjusted to maintain an acceptable value. The nutrient solution can be recycled for awhile, then replaced with fresh nutrient solution.

Growing Medium

There are two main types of hydroponics: solution culture and medium culture. In solution culture, no growing medium is used; the roots are bathed or sprayed with nutrient solution. In medium culture, a growing medium replaces the soil and acts as an anchor and stabilizer for the plant. It provides delivery of both oxygen and nutrient solution to the plant roots. Popular growing mediums include expanded clay pellets, rock wool, perlite, vermiculite, sand and gravel.

Passive Systems

Passive hydroponic systems are ideal for the beginner. They are less complicated and allow the gardener to learn the basics of hydroponic gardening. Passive hydroponic systems rely on hand watering or a wicking action rather than pumps and timers, and may result in less than ideal oxygen uptake. Passive systems require the gardener to manage the nutrients closely, resulting in lower costs for nutrients and higher labor requirements.

Active Systems

Active systems use a pump on a timer to deliver the nutrient solution to the plants. The roots are flooded with nutrients and drained on a cycle that provides optimal nutrient and oxygen delivery. A well-maintained active system will be more productive than either soil or passive hydroponic systems. Active systems are more complicated and expensive to start, and are dependent on a steady supply of electricity and mechanical pumps and timers. A power outage or pump failure could result in damage or death to the plants.


The ideal light for hydroponic systems is sunlight. When growing indoors, artificial grow lights are available to supply the light needed. Metal Halide (MH) lights are suitable for green leafy plants and produce such as lettuce and spinach. High Pressure Sodium (HPS) lights are best for the flowering phase of the plants lights. A combination of MH and HPS lights provides the right wavelengths for every stage of the plant's life.

Keywords: hydroponic gardening, medium culture, grow lights

About this Author

Diane Watkins has been writing since 1984, with experience in newspaper, newsletter and Web content. She writes two electronic newsletters and has a Bachelor of Science degree in chemistry from Clemson University. She has taken graduate courses in biochemistry and education.