Understanding Hydroponics; Hydroponic Growing Methods Support Healthy Plant Growth and Yield; An Introduction to Hydroponics for Beginners

Introduction to Hydroponics:

The quick and simple way of describing hydroponics is growing plants with nutrient rich water outside of a soil base.  The term “hydroponics” is a derivative of two Greek words.  The Greek word “hydro” means water and “ponics” means labor.  Hydroponics is a form of soil free gardening.

Soil is often used as a medium that hosts a plant’s root system and helps to deliver water and nutrients to the plant’s root system.  In a hydroponic system, the water which is infused with nutrients, is delivered to the plant’s root system.  The technique of growing plants outside of soil has been developing over hundreds of years.  Scholars and scientists throughout history have debated the merits of growing plants outside of a soil based medium and this debate continues currently.  These days, organizations like NASA continue to develop the techniques so that grow systems can be set up in soil free environments.  A combination of hydroponics and LED grow lights have been used to set up plant grow systems in space.

A couple advantages of utilizing hydroponics over other more traditional growing methods include control and efficiency.  Using hydroponic techniques can be done in a more confined space than traditional soil grow methods.  Use of the nutrient solution in hydroponics allows a grower to acutely control what nutrients are being presented to the plant.  Also, there are few pests issues and no weed or pesticide issues to contend with when growing with a hydroponic system.  The hydroponic system can be put together in a confined space and plant yield can be better than the yield outcomes given similar space when using soil growing methods.

Hydroponic grow systems can be designed in multiple ways.  The plant’s root system may grow directly in the nutrient solution.  The plant may also be misted by the solution or the root system could grow in a substrate replacement  for soil.  There are two primary techniques used most often when growing hydroponically.  There is the solution culture technique that does not use a solid medium for the roots, and there is the medium culture technique which provides a soil-free alternative culture in which the roots develop.

Throughout the rest of this hydroponic grow review, I will share the basics of several hydroponic growing techniques, and add additional pros and cons associated with the methods.

Solution Culture techniques for Hydroponic Growing:

In a solution culture, there is no medium used for soil.  The plants’ roots grow in direct contact with a presented nutrient solution.  There are three primary solution culture techniques utilized for hydroponic growing.  Hydroponic growing can happen in a static solution, in a continuous flow solution, or the method of aeroponics can be employed.

Static Solution Culture:

A static solution culture is designed to allow plants to grow in a nutrient water solution held inside of a containment unit.  Plant roots are placed in the static solution and are kept there while the plant develops.  The unit holding the solution and plant can be anything from a jar or plastic bucket, to a more industrial sized tank set-up. 

The nutrient solution can be aerated or not, but if the solution is not aerated, then the nutrient solution should be diluted so as not to deprive the root system of adequate oxygen.  I recommend that the solution be aerated.  Oxygen can be presented via an aquarium air pump, other aquatic pump or an airstone.  For indoor growers, many set up the grow system in a common mason jar or small plastic container.  If you decide to go with the mason jar, the outside can be covered to reduce light that would promote algae growth.  A grower can cover the outside of the jar with butcher-block paper or with aluminum foil.

In a static hydroponic system, the set-up can be an open or closed set-up.  In an open system, the nutrient solution can be continuously presented new like in a drip irrigation set-up.  In the closed system, the nutrient solution is used for as long as it is chemically beneficial.  An example of a closed system is one where the nutrient solution continuously stays in contact with the roots system until it is not viable any longer.  The nutrient solution should be changed periodically when utilizing a closed static system, for instance once per week, but indoor growers can be more precise with nutrient solution changes by using an electrical conductivity meter.

Continuous Flow Solution Culture:

This system is one of the more productive when it comes to forms of hydroponics, but it is a bit more complicated than say a static set-up.  Generally, in a continuous flow set-up, the nutrient solution constantly flows past the roots of the plant.  It is like growing plants in a stream of nutrient solution.  This system is often used in a more commercialized setting as it can service thousands of plants at one time.  One popular way is to use plastic pipe with holes cut into the pipe.  The plant grows from the hole and the roots extend down into the pipe while the nutrient solution continuously flows through the roots.  One advantage of this system is that it allows the root systems to be oxygenated easily.  One big disadvantage of this type of system is that if it stops working, like when the power is interrupted and the nutrient solution flow stops, the plants have little to live on until you get the system up and running again.

Aeroponics:

The method of aeroponics is beneficial for growing new clones or cuttings and is generally described as the process of growing plants in an air or mist environment without the use of soil or other alternative medium.  An aeroponic method is not necessarily a hydroponic technique in that is does not rely on utilizing a liquid nutrient solution in which the plant roots grow.  However, it does rely on a nutrient rich solution that is often misted into the air to feed the plant.  Some consider it an off-shoot of hydroponics.  The nutrient rich solution can be misted onto the plant and the dangling plant roots with sprayers instead of submerging the roots in the nutrient rich solution like in the methods described above.  The misting can happen almost continuously.   One primary advantage of an aeroponics system is that the roots are easily aerated and you do not have to worry about water logging the plants.  NASA research also shows that yield of aeroponically grown plants surpasses the yield of plants grown in a system that submerges plant roots in nutrient solution.

Medium Culture Techniques for Hydroponic Growing:

Growing plants hydroponically in a medium culture means that you are growing plants in a soil-free alternative medium.  The plant roots grow through this medium instead of growing through soil, but are fed hydroponically.  Growing roots through an alternative soil-free medium is conducted to channel the nutrient solution to the plant’s root system all while supporting the process of aeration.  The solid medium alternative for soil might be rock, sand, gravel, pumice, perlite, rock wool, coir,  or wood fiber and there are other medium alternatives as well.

Sub-Irrigation or seepage irrigation is a method of irrigation where a nutrient solution is delivered to the plant roots from below and the nutrient solution is absorbed upward through the porous medium.

The ebb and flow sub-irrigation technique is one that utilizes an automated pump to fill a reservoir with nutrient solution that is then absorbed upward through the porous medium to feed the plant roots.  The pump supplies nutrient solution until it hits a drain point which then allows the nutrient solution to drain into a holding tank.  The process then repeats itself.

The run to waste method is another form of medium culture hydroponic growing.  This technique has plants growing in the soil free medium alternative and watered with the nutrient solution routinely.  The excess nutrient solution run-off is held in a reservoir and can be reused after filtration takes place.  This is not a common method for the grower just starting to think about growing hydroponically.

The Nutrient Solution used in a Hydroponic Grow System:

A nutrient solution can consist of organic nutrients, or chemical nutrients.  Organic nutrients can sometimes clog lines in a pump system which can lead to more work and down time.  Using chemical nutrients as the main food supply is the popular choice of many hydroponic growers due to the ease and consistency of implementation.  Nutrient solutions can be found at your local hydroponics store or on-line.

General Advantages of Utilizing a Hydroponic Grow System:

• soil is not needed as a medium in which to grow the plant’s root system
• several hydroponic growing methods can be put together in a small space
• the growth rate for plants grown hydroponically has been shown to be faster, up to 50 percent faster, than the growth rate of soil grown plants
• yields can be better than traditional soil planting methods
• added oxygen to the roots in a hydroponic grow system stimulates enhanced growth and development
• few to no pests and worry over pesticide toxicities are greatly reduced
• plant roots find the nutrients faster in a hydroponic grow system and the nutrient rich solution is made available to the plant more routinely which boosts plant development
• hydroponically grown plants will use less energy than soil grown plants to break down the food they need and so saved energy can be utilized for faster plant growth and a more robust yield
• environmentally friendly in that chemicals are not necessary for pest control
• environmentally friendly because hydroponic gardening requires less water to support plant growth than soil grown plants
• environmentally friendly since growing hydroponically does not negatively affect erosion of available topsoil
• it is generally a stable system that can be relatively easy to set up and control
• harvesting can be easier than in other more traditional soil growing methods.

Disadvantages:

• Requires the use of uncontaminated water
• environmental conditions associated with hydroponics can support algae and bacteria growth