The word, Hydroponic, comes from Latin and means working water. Simply put, it is the art of growing plants without soil.
When most people think of hydroponics, they think of plants grown with their roots suspended directly into water with no growing medium. This is just one type of hydroponic gardening known as N.F.T. (nutrient film technique). There are several variations of N.F.T. used around the world and it is a very popular method of growing hydroponically. What most people don’t realize is that there are countless methods and variations of hydroponic gardening. In this section, we explain the most common, including the pros and cons of each along with an abundance of great, general information about hydroponics.
Basic Hydroponic Systems and How They Work
There are 6 basic types of hydroponic systems; Wick, Water Culture, Ebb and Flow (Flood & Drain), Drip (recovery or non-recovery), N.F.T. (Nutrient Film Technique) and Aeroponic. There are hundreds of variations on these basic types of systems, but all hydroponic methods are a variation (or combination) of these six. Scroll down this page (or click on the system names) to see drawings and a description of each type of hydroponic system.
The Wick system is by far the simplest type of hydroponic system. This is a passive system, which means there are no moving parts. The nutrient solution is drawn into the growing medium from the reservoir with a wick. Free plans for a simple wick system are available (click here for plans).
This system can use a variety of growing medium. Perlite, Vermiculite, Pro-Mix and Coconut Fiber are among the most popular.
The biggest draw back of this system is that plants that are large or use large amounts of water may use up the nutrient solution faster than the wick(s) can supply it.
The water culture system is the simplest of all active hydroponic systems. The platform that holds the plants is usually made of Styrofoam and floats directly on the nutrient solution. An air pump supplies air to the air stone that bubbles the nutrient solution and supplies oxygen to the roots of the plants.
Water culture is the system of choice for growing leaf lettuce, which are fast growing water loving plants, making them an ideal choice for this type of hydroponic system. Very few plants other than lettuce will do well in this type of system.
This type of hydroponic system is great for the classroom and is popular with teachers. A very inexpensive system can be made out of an old aquarium or other water tight container. We have free plans and instructions for a simply water culture system (click here for free plans).
The biggest draw back of this kind of system is that it doesn’t work well with large plants or with long-term plants.
The Ebb and Flow system works by temporarily flooding the grow tray with nutrient solution and then draining the solution back into the reservoir. This action is normally done with a submerged pump that is connected to a timer.
When the timer turns the pump on nutrient solution is pumped into the grow tray. When the timer shuts the pump off the nutrient solution flows back into the reservoir. The Timer is set to come on several times a day, depending on the size and type of plants, temperature and humidity and the type of growing medium used.
The Ebb & Flow is a versatile system that can be used with a variety of growing mediums. The entire grow tray can be filled with Grow Rocks, gravel or granular Rockwool. Many people like to use individual pots filled with growing medium, this makes it easier to move plants around or even move them in or out of the system. The main disadvantage of this type of system is that with some types of growing medium (Gravel, Growrocks, Perlite), there is a vulnerability to power outages as well as pump and timer failures. The roots can dry out quickly when the watering cycles are interrupted. This problem can be relieved somewhat by using growing media that retains more water (Rockwool, Vermiculite, coconut fiber or a good soiless mix like Pro-mix or Faffard’s).
Drip systems are probably the most widely used type of hydroponic system in the world. Operation is simple, a timer controls a submersed pump. The timer turns the pump on and nutrient solution is dripped onto the base of each plant by a small drip line. In a Recovery Drip System the excess nutrient solution that runs off is collected back in the reservoir for re-use. The Non-Recovery System does not collect the run off.
A recovery system uses nutrient solution a bit more efficiently, as excess solution is reused, this also allows for the use of a more inexpensive timer because a recovery system doesn’t require precise control of the watering cycles. The non-recovery system needs to have a more precise timer so that watering cycles can be adjusted to insure that the plants get enough nutrient solution and the runoff is kept to a minimum.
The non-recovery system requires less maintenance due to the fact that the excess nutrient solution isn’t recycled back into the reservoir, so the nutrient strength and pH of the reservoir will not vary. This means that you can fill the reservoir with pH adjusted nutrient solution and then forget it until you need to mix more. A recovery system can have large shifts in the pH and nutrient strength levels that require periodic checking and adjusting.
This is the kind of hydroponic system most people think of when they think about hydroponics. N.F.T. systems have a constant flow of nutrient solution so no timer required for the submersible pump. The nutrient solution is pumped into the growing tray (usually a tube) and flows over the roots of the plants, and then drains back into the reservoir.
There is usually no growing medium used other than air, which saves the expense of replacing the growing medium after every crop. Normally the plant is supported in a small plastic basket with the roots dangling into the nutrient solution.
N.F.T. systems are very susceptible to power outages and pump failures. The roots dry out very rapidly when the flow of nutrient solution is interrupted.
The aeroponic system is probably the most high-tech type of hydroponic gardening. Like the N.F.T. system above the growing medium is primarily air. The roots hang in the air and are misted with nutrient solution. The mistings are usually done every few minutes. Because the roots are exposed to the air like the N.F.T. system, the roots will dry out rapidly if the misting cycles are interrupted.
A timer controls the nutrient pump much like other types of hydroponic systems, except the aeroponic system needs a short cycle timer that runs the pump for a few seconds every couple of minutes.
Why does Hydroponics work so well?
That’s simple. If you give a plant exactly what it needs, when it needs it, in the amount that it needs, the plant will be as healthy as is genetically possible. With hydroponics this is an easy task; in soil it is far more difficult.
With hydroponics the plants are grown in an inert growing medium (see below) and a perfectly balanced, pH adjusted nutrient solution is delivered to the roots in a highly soluble form. This allows the plant to uptake its food with very little effort as opposed to soil where the roots must search out the nutrients and extract them. This is true even when using rich, organic soil and top of the line nutrients. The energy expended by the roots in this process is energy better spent on vegetative growth and fruit and flower production.
If you grow two genetically identical plants using soil for one and hydroponics for the other, you will almost immediately see the difference this factor makes. Faster, better growth and much greater yields are just some of the many reasons that hydroponics is being adapted around the world for commercial food production as well as a growing number of home, hobby gardeners.
Growing medium is the material in which the roots of the plant are growing. This covers a vast variety of substances which include Rockwool, perlite, vermiculite, coconut fiber, gravel, sand and many more. The growing medium is an inert substance that doesn’t supply any nutrition to the plants. All the nutrition comes from the nutrient solution (water and fertilizer combined). You can therefore, easily control everything the plants receive. The strength and pH of the nutrient solution is easy to adjust so that the plants receive just the right amount of food. The watering/feeding cycles can be controlled by an inexpensive timer so that the plants get watered on schedule, as needed.
Both hydroponic fertilizers and those intended for use in soil contain the three major nutrients, nitrogen, phosphorus and potassium. The major difference in hydroponic fertilizers is that they contain the proper amounts of all the essential micro-nutrients which fertilizers intended for use with soil do not. The plants are expected to find these elements in the soil, assuming that the trace elements are in fact present. Problems can arise for the plants if any or all of the micro-nutrients are not present in the soil or are depleted by successive (or excessive) plantings. Hydroponic fertilizers are usually in a more refined form with fewer impurities making them both more stable and soluble for better absorption. Organic fertilizers, in most cases, are very different than either hydroponic or soil fertilizers both in composition and how they deliver the nutrient to the plants. Organic fertilizers rely on the synergistic action of bacteria and microbes to break down nutritional substances for easier uptake by the plants. Hydroponic and soil fertilizers provide nutrients in a ready-to-use form. While once, they were mutually exclusive, in recent years a number of outstanding organic fertilizers have hit the market in formulations refined enough for use in hydroponics. For more information click on the excellent article below.
“Hydroponic or Organic-What’s the Difference?” by Roger H. Thayer
The micro-nutrients, also known as trace elements that are required for healthy plant growth are calcium, magnesium, sulfur, boron, cobalt, copper, iron, manganese, molybdenum and zinc. When deficient in any or all of these elements plants suffer stress, disease, become more susceptible to pest, fungus’ and bacteria, and may have uptake issues with the N-P-K fertilizer they are being fed. At best, they will never live up to their genetic potential in growth and yield; at worst, they die. In the case of food crops, nutrient deficient plants lead to nutrient deficiencies in the people and animals who consume them. Due to years of over farming the same fields much of today’s commercially produced food has a nutrient level barely exceeding waxed fruit. No surprise that more and more people are choosing to grow the food their families eat in their own gardens. When growing in soil remember to renew the dirt between plantings and when growing hydroponically know that it is absolutely essential to use a hydroponic fertilizer that provides all the trace elements.
It can be but it doesn’t have to be. Hydroponics can be as incredibly simple as growing a single plant in a hand watered bucket or nursery pot, using any number of inert growing mediums. No automation, electricity or grow lights required.
Of course, the potential to go high tech is limited only by your imagination and budget. Virtually every aspect of garden management can be automated and should you so desire, monitored and controlled with your laptop or cell phone from the other side of the world. Dare to dream.
Most hobby oriented hydroponic systems are somewhere between the two extremes mentioned above. The average, home hydroponic system usually consists of a few basic parts: a growing tray, a reservoir, a submersible pump to water the plants, a simple timer and an air pump and air stone to oxygenate the nutrient solution. Of course, light (either natural or artificial) is also required.
The control of pH is extremely important, not only in hydroponics but in soil as well. Plants lose the ability to absorb different nutrients when the pH varies. (This topic is answered in much greater detail in the “mini-class” on pH in Hydroponics).
The ability to quickly and easily test and control pH in hydroponics is a major advantage over dirt gardening, where testing and adjusting the pH is much more complicated and time consuming.
Source: Hydroponics University