What Is Aeroponics?

How Aeroponics Works, Types, and Pros and Cons

Growing rice in an aeroponics system
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Aeroponics is an advanced variation of hydroponics where plants are suspended in the air; their roots dangle down and are periodically misted with water from a timed sprinkler system connected to a main nutrient reservoir. This soilless growing method is best for plants that need more oxygenation, since aeroponic roots aren’t hampered by dense soil or thick growing mediums. Depending on the plant and specific type of aeroponics system, the grower typically uses little to no growing media at all.

In aeroponics, a specially designed pump and spray system is submerged into the nutrient-water solution and timed to release short mists of water to the plants’ roots throughout the day. Because roots will have more access to oxygen and humidity in an aeroponics system, they often grow larger and yield far bigger numbers than traditional farming methods. Generally, it also uses less water over time since excess water not absorbed by the roots is drained back into the nutrient tank, and the mist allows for higher concentrations of nutrients with less liquid.

Most of the plants that work with hydroponics will thrive in an aeroponics system, from leafy greens and herbs to tomatoes, cucumbers, and strawberries, but with additional perks. Because of the exposed root qualities of aeroponics systems, root vegetables like potatoes that would otherwise be ill-suited for hydroponics systems will flourish as they’ll have more room to grow and be easier to harvest.

Lettuce growing in an aeroponics greenhouse
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Aeroponics in Space

NASA began experimenting with aeroponics as early as 1997, planting adzuki beans and seedlings aboard the Mir space station in zero gravity and comparing them to controlled aeroponic gardens on Earth treated with the same nutrients. Amazingly, the zero gravity plants grew more than the plants on Earth. Aeroponics can not only provide long-mission deep-space NASA crews with fresh food, but it also has the potential to provide them with fresh water and oxygen.

How Does Aeroponics Work?

The seeds are planted somewhere they’ll stay in place, such as pieces of foam, pipes, or foam rings, which are then wedged into small pots or a perforated panel with a tank full of nutrient solution below. The panel elevates the plants so they’ll be exposed to the natural (or artificial) light and circulating air, providing light on the top and nutrient mist on the bottom, and an enclosure around the roots helps keep the moisture in. A timed pump rests inside the tank or reservoir, pumping solution up and through spray nozzles that mist the roots, with excess liquid draining straight down through an outflow chamber back into the reservoir. At the next timed interval, the entire cycle starts again.

Close up of aeroponic plant roots
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Nutrients for aeroponics systems, like hydroponics, come packaged in both dry and liquid forms. Depending on the plant and growth stage, primary nutrients may include nitrogen, phosphorus, and potassium, while secondary nutrients can range from calcium and magnesium to sulfur. It is also important to consider micro-nutrients, such as iron, zinc, molybdenum, manganese, boron, copper, cobalt, and chlorine.

Natural Aeroponics

Aeroponics occurs in nature, specifically in more humid and wet regions like the tropical islands of Hawaii. Near waterfalls, for example, plants will grow vertically on the rocks with their roots openly hanging in the air, the spray from the waterfall moistening the roots under the right conditions.

Types of Aeroponics

There are two types of commonly used aeroponics: low pressure and high pressure. Low pressure is the most used by home growers since it is low cost, easy to set up, and its components are easier to find. However, this type of aeroponics often uses a plastic spray nozzle and a typical fountain pump to deliver nutrients, so the droplet sizes are not exact and can sometimes waste more water.

In aeroponics systems where the nutrient solution is continuously recycled, the pH measurements need to be taken regularly to ensure that enough nutrients are getting absorbed into the plants.

High-pressure aeroponics, on the other hand, distributes nutrients through a highly pressurized nozzle that can deliver smaller water droplets to create more oxygen in the root zone than low-pressure techniques. It is more efficient, but much more costly to set up, so it tends to be reserved for commercial production rather than hobbyists.

High-pressure systems typically mist for 15 seconds every 3 to 5 minutes, while low-pressure systems may spray for 5 minutes straight every 12 minutes. Experienced growers will adjust the spraying interval according to the time of day, watering more frequently at night when the plants are less focused on photosynthesis and more focused on taking up nutrients. With both types, the reservoir solution is kept at a temperature range between 60 F and 70 F in order to maximize the absorption rate of the plant. If the water becomes too hot, it is more susceptible to algae and bacteria growth, but if it gets too cold, the plants may start to shut down and not take as many nutrients as they would at a more optimal temperature.

Aeroponics at Home

While some growers choose to use horizontal aeroponic systems similar to traditional soil farming, vertical systems can save more space. These vertical systems come in all shapes and sizes, even small enough to be used on a back porch, balcony, or even inside an apartment with the appropriate lighting setup. In these smaller systems, misting devices are placed on top, allowing gravity to evenly distribute the nutrient solution as it spreads downward.

Vertical aeroponic basil in a greenhouse during winter
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Aeroponics kits are available to make the set up process easier for beginners, but it is also possible to design and build your own system at home, similar to hydroponics, with tools found at most local gardening stores. Due to the complicated and expensive nature of high-pressure aeroponics, it is always prudent for beginners to start off with a low-pressure system before working their way up to more technical operations.

Fun Fact

The first recorded use of aeroponics happened in 1922, when B.T.P. Barker developed a primitive air plant-growing system and used it to research plant root structure in a laboratory setting. By 1940, researchers were frequently using aeroponics in plant root studies, as the dangling roots and lack of soil made it much easier to observe changes.

Pros and Cons

One of the most significant advantages of aeroponics systems is the fast and high crop yield and the fact that it uses the least amount of water over time compared to hydroponics and aquaponics. Roots are exposed to more oxygen, helping them absorb more nutrients and grow faster, healthier, and larger. Also, the lack of soil and growing medium means that there are fewer threats of root zone diseases.

On the flip side, aeroponic system chambers are constantly being sprayed with mist, keeping them wet and prone to bacteria and fungi; this can be remedied by cleaning and sterilizing misters and chambers regularly.

Affordability Factor

Studies show that the cost of growing a tuber (such as potatoes, jicama, and yams) using aeroponics is about one-quarter less than the cost of a conventionally grown tuber.

Due to the circular nature of the watering system and the higher nutrient absorption rate, aeroponics uses considerably less water than similar farming systems. Aeroponic equipment is also easier to move and requires much less space (nurseries can even be stacked on top of each other like a modular system). In a study comparing lettuce growth aeroponics, hydroponics, and substrate culture, results showed that aeroponics significantly improved root growth with greater root biomass, root-shoot ratio, length, area, and volume. The study concluded that aeroponics systems may be better for higher-valued crops.

Stacks of aeroponics rice plants
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Because the plants aren’t submerged in water, aeroponics is completely dependent on the misting system. If anything malfunctions (or in the event of power outages), then the plants will quickly dry up and die without water or nutrients. Seasoned growers will think ahead and have some sort of backup power and misting system waiting in storage in case the primary one fails. The system’s pH and nutrient density ratio is sensitive, and will require plenty of hands-on experience to understand how to properly balance them; as there is no soil or media to absorb the excess nutrients, proper knowledge about the perfect amount of nutrients is essential to aeroponics systems.

View Article Sources
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