There are many different hydroponic systems available to gardeners, each meeting plant needs in slightly different ways. While the choices can seem intimidating at first, they have much in common.
Roots (and the plants they are attached to) require above all else access to both air and water. Nutrients are also important, but that’s a topic for another article. For now, assume the nutrients can be added to the water to make a nutrient solution.
Most of the differences between growing systems are in the specifics of how they make water and air available to the root system. For example, a houseplant in a flower pot filled with soil may get watered from a watering can, and is allowed to dry out somewhat between waterings, giving the plant access to both water and air.
If the plant isn’t watered, it will dry out and die, but if the plant is watered too often, it doesn’t have enough access to air, and the plant will drown. In my experience, the most common error in gardening is overwatering.
On the other hand, just as with people, too much air and too little water causes dehydration, but of the two scenarios, slight dehydration is a less traumatic experience than a slight drowning. While creating a watering schedule, a little too dry is a smaller error than a little too wet. Here is a roundup of some common growing systems.
The benefits of growing plants in pots of soil are numerous. Soil buffers against changes, is a natural root support structure and is a familiar medium to many. The drawbacks? Soil-based gardening tends to be heavy—large pots are required—and soil holds moisture so well that it is easy to overwater plants.
Soilless mixes are designed to mitigate these drawbacks by using ingredients such as peat, coir and compost. These mixes tend to be lighter and are commonly used in nurseries for potted plants. They can be hand-watered to provide moisture, and allowed to dry slightly between waterings to provide access to air.
This is considered a hydroponic method of growing since plants are not grown in soil, but the experience is similar to growing in soil, which makes them a good choice for the average houseplant. There are a variety of soil alternatives that can be used, each with slightly different watering needs, since some hold water longer than others.
If the flowerpot is filled with a grow medium, and set in a tray with water, it is a passive hydroponic system. As the media dries, capillary action draws water to the roots either directly from the tray or through a wick, although in practical applications, occasionally watering the top of the media to introduce new solution can help flush the media.
The media should be airy or allowed to slightly dry so that water is not allowed to stand long enough for the dissolved oxygen to disperse and start to become anaerobic. This type of system is simple to set up, and can be an easy first step into the world of hydroponics.
Simply fill a pot with your chosen grow media, such as perlite, set in a tall dish or 1020 tray, and water by hand with a hydroponic nutrient solution as needed. For the price of some grow media and a couple of bottles of fertilizer you can try a simple passive hydroponic system.
Hand watering works well as long as the gardener has the time and patience to do it regularly. The addition of a pump to the system creates an active hydroponic system and can save effort.
Sprinkler systems use pumped water to spray the top of the media, which soaks down to the root system. Aeration is achieved by using fresh water and allowing the media to partially dry before watering. Sprinkler systems are often run to waste, meaning runoff is not recovered, or as part of a recirculating system.
They are inexpensive, but generally less exact than other systems. The spray can be difficult to contain, and therefore traditional sprinkler systems are not recommended for a home indoor garden where water damage may result.
Drip systems use pumped water and low-volume emitters. The slow-dripping action allows the water to be absorbed over a longer period of time, allowing for greater penetration with less runoff and uncontrolled spray than traditional sprinklers. Aeration is regulated by the media used, the amount the media is allowed to dry between nutrient applications and the amount of air bubbled into the solution.
Nutrient Film Technique
Nutrient film technique uses a low volume of nutrient solution continuously applied to the roots. An NFT system functions much like a continual drip. The roots are constantly exposed to a thin film of aerated nutrient either with or without a mat used as a grow medium. Aeration needs are met by the exposed roots above the film or mat, and by use of an aerated solution.
Ebb and Flow
Ebb and flow (also called flood and drain) systems flood the medium containing the roots and then allow the water to drain away, giving the roots access to air. A timer usually controls the waterings. A well-aerated solution will help buffer minor overwatering.
Deep Water Culture
Deep water culture systems can be as simple as letting the roots dangle in a nutrient solution and adding an air stone for aeration. Because air is pumped into the water, the solution does not go stagnant and the plant can absorb both air and water. These simple systems are sometimes referred to as bubblers.
Aeroponic systems use the same basic principles as DWC, but instead of adding air to the solution, the nutrient solution is sprayed into the air and onto the roots.
When considering which system is best for a given situation, take a look at all the available options. Many commercial kits are available, often using a combination of the above principles. When considering which is most appropriate for your needs, look at how each supply water and air to the root system.
Soil is common, but tends to have the most insect issues. Hand watering works well for a few plants, but can become arduous if there are a large number of plants to be tended. Pre-fabricated systems are more expensive, but DIY systems tend to require more creativity and understanding of the principles involved.
Aeroponic systems make beautiful roots, but require continuous electrical usage with little tolerance for a power failure.
Now that you know the basics of growing and have an idea about which system or systems you might want to try, visit your local hydroponics retailer to learn more.