Hydroponics is the process of growing plants without soil using a nutrient-rich water solution. Hydroponic systems range in size from small personal systems to large commercial systems that produce food for public food supply. These systems use a variety of media to support the plants, such as rock wool or clay beads. The main distinguishing feature of any hydroponic system is that all of the nutrients needed by the plant are supplied by a water solution.
While hydroponics might seem to be a relatively new technique, it’s actually a fairly old method of growing plants, dating back to the 1600s when scientists first began working with plants in water media. Sir Francis Bacon, whose work was published posthumously in Sylvas Sylvarum, was among the first scientists to implement hydroponics. Following Bacon, several others made advancements in the study of hydroponics, such as John Woodward, who attempted to grow spearmint in various water solutions.
The term hydroponics, from the Greek hydros for water and ponos for labor, was coined in the 1930s by William Gericke. During his time at University of California, Berkeley, Gericke grew tomato plants in water and nutrient solutions at his home. Two other scientists from Berkeley, Dennis Hoagland and Daniel Arnon, built on Gericke’s work when they wrote and published the bulletin Water Culture Method for Growing Plants without Soil in 1938. It includes a wealth of information about hydroponics, some of which is still referenced and used today.
Hydroponics was first used for commercial purposes during the late 1930s when tanks holding mineralized water were used to grow crops on Wake Island, a small landmass in the Pacific Ocean. Pan-Am Airways regularly made refueling stops at this island, and they fed airline staff and crew with the food that was grown there.
Advantages of hydroponics
- Space efficiency. Plants grown hydroponically often take up less space than plants grown in soil. In traditional farming, a plant takes up ground space. With vertical hydroponics, many plants can be grown above and below each other. This allows for more plants in a smaller area. Additionally, as nutrient solutions can be tailored to the plants being grown and the system in which they are grown, plants can often be grown closer together in hydroponic systems.
- Variety of environments. The diverse nature of hydroponic plants means they can grow well in most environments, including cities and deserts. Because hydroponic systems are typically set up indoors, they usually use artificial light and are often climate controlled. Growing plants in a traditional manner makes it necessary to consider the season and growing zone, but hydroponics eliminates this need.
- Weeds. With their typical indoor setting, most hydroponic plants are not exposed to many of the weeds that compete with traditional plants. Seeds from weeds that may take root in a crop field or garden are unlikely to make it into a hydroponic system. Additionally, because they aren’t grown in soil, weeds that send shoots outward are not able to get into a hydroponic system.
- Pests. Plants grown indoors are not exposed to many of the outdoor pests that plague traditional farming. Because hydroponic plants aren’t grown in soil, soil-dwelling pests that may damage plant roots are not a problem, and fewer pests mean fewer pesticides need to be applied.
- Water conservation. Unlike traditionally grown plants where much of the water naturally drains into the soil and is lost to the environment, many hydroponic systems reuse water as nutrient solutions are cycled.
- Disease. Hydroponically grown plants typically have less problems with disease than plants grown in the soil. Many plant diseases begin in the soil due to microorganisms that occur there. Plants grown in hydroponic systems lack exposure to these microorganisms and therefore have lower disease rates.
- Pollution. In traditional farming and gardening, water runoff carrying fertilizers, pesticides, and other chemicals can cause pollution in natural bodies of water. In hydroponics, there is no water runoff so there is less risk of pollution.
Disadvantages of hydroponics
- Cost. In many cases, the initial hydroponics investment can be costly. Growing containers, appropriate lighting, pumps, solutions, and other materials must be purchased.
- Power outages. Because many hydroponic systems rely on pumps and artificial lighting, power outages can cause problems. Plants may need to be watered by hand if the pumps are not functional.
- Technical knowledge. Hydroponic systems may require technical knowledge in addition to basic gardening knowledge. This is especially true if you’re creating a more advanced system, which may require some knowledge of engineering. Also, if you’re not using a premade nutrient solution, you might need to know certain chemistry and biology principles.
- Maintenance. Some hydroponic systems may require a good amount of time for regular maintenance. Cleaning the tanks and mixing solutions could be time consuming.
Types of hydroponic methods and systems
There are six types of frequently used hydroponic systems. Although these systems are the most common, other types and combinations of systems exist.
- Wick. In this type of hydroponic system, a reservoir contains a nutrient solution. This nutrient solution is drawn up into the growing medium using a wick. This system has no pumping system, but it does typically contain an airstone in the nutrient solution. The disadvantage to using this type of system is that some types of plants (especially larger plants) may require more nutrient solution than the wick can deliver.
- Water culture. In this type of hydroponic system, a floating platform to which the plants have direct access is placed in a nutrient solution. Instead of a pump, this system usually has an air stone in the nutrient solution. Lettuce is often grown in this manner.
- Drip system (recovery or non-recovery). In this system, nutrient solution is pumped from a reservoir to the growing area where it then exits through a drip line. The solution is dripped at the base of the plant through a growing medium, similar to natural rainwater. The nutrient solution then travels through the media and exits through an overflow tube. In recovery systems, this excess nutrient solution goes back into the reservoir. In a non-recovery system, any excess solution is discarded.
- Ebb and flow (fill and drain). This type of hydroponic system consists of a main water reservoir and growing area. At set times, the growing area fills from the bottom up with nutrient water pumped from the main reservoir. After the growing area fills, the nutrient water is then pumped back into the reservoir container. As the water leaves the growing medium, fresh air is pulled down into the gaps in the growing medium, aerating the roots.
- Nutrient film technique (NFT). In this type of hydroponics, there is a constant flow of nutrient solution. The growing area is typically angled, and the nutrient solution is pumped to the higher end of the growing tray. The nutrient solution then travels down the slope to the end of growing tray, where it flows down a tube back into the reservoir.
- Aeroponics. This hydroponic system provides minimal support for the root structures, which hang freely. Aeroponics uses a misting technique, relying on either water pumps and tubing or pumped air to deliver nutrient water and thereby keep the roots both saturated and aerated. Small droplets of nutrient water become airborne in the system and collect on the suspended plant roots. Excess water drips from the roots back to the reservoir.
Aquaponics is the combination of hydroponics with aquaculture. Both plants and fish can be raised in an aquaponics system. In these systems, water from the tank containing the fish, or aquaculture, is pumped through a filter to remove solid wastes. The water is then pumped into the hydroponic system. In essence, the aquaculture is the nutrient reservoir for the plants. The water from the aquaculture is then removed from the hydroponic area, and occasionally it goes through more filtration before traveling back to the fish. The plants in the hydroponics portion remove nutrients that they need from the aquaculture water. The nutrients that the plants need are toxic to the fish in high concentrations.