The basic principle of aeroponics growing is to grow plants suspended in a closed or semi-closed environment by spraying the plant’s dangling roots and lower stem with an atomized or sprayed, nutrient-rich water solution. The leaves and crown, often called the canopy, extend above. The roots of the plant are separated by the plant support structure. Often, closed-cell foam is compressed around the lower stem and inserted into an opening in the aeroponics chamber, which decreases labor and expense; for larger plants, trellising is used to suspend the weight of vegetation and fruit.
Compared to hydroponics, aeroponics offers even more control over the root system, because you don’t need to immerse the roots into any liquid. Aeroponics uses a small internal microjet spray that sprays the roots with fine, high pressure mist containing nutrient rich solutions. Because the roots are exposed to more oxygen, the plant tends to grow faster. It is also easier to quickly administer all sorts of nutrients to the plant, via the root system.
In a typical aeroponics system, plants are usually suspended on top of a reservoir, within a tightly sealed container. A pump and sprinkler system creates vapors out of a nutrient rich solution, and sprays the result in the reservoir, engulfing the dangling plant roots. Plants are inserted into the platform top holes and supported with collars. Aeroponics is often confused with hydroponics, since the two methods are similar and interchangeable, but In aeroponics the roots have no contact with any media, whereas in hydroponics, they do.
Ideally, the environment is kept free from pests and disease so that the plants may grow healthier and more quickly than plants grown in a medium. However, since most aeroponics environments are not perfectly closed off to the outside, pests and disease may still cause a threat. Controlled sterile environments advance plant development, health, growth, flowering and fruiting for any given plant species and cultivars.
Due to the sensitivity of the root systems, aeroponics is often combined with conventional hydroponics, which is used as an emergency “crop saver” – backup nutrition and water supply – if the electricity or the aeroponics pump or spray apparatus fails. High-pressure aeroponics is defined as delivering nutrients to the roots via 20–50 micrometer mist heads using a high-pressure (80 pounds per square inch (550 kPa)) diaphragm pump and a timer to cycle it on and off.
Some of the key benefits of aeroponics:
The chief feature of aeroponics is the plants grow faster because their roots have access to a lot of oxygen 24/7.
Easy system maintenance – In aeroponics, all you need to maintain is the root chamber (the container housing the roots) which needs regular disinfecting, and periodically, the reservoir and irrigation channels. The constant semi-moist environment of the root chamber which invites bacterial growth is the main drawback of all aeroponic system maintenance.
Less need for nutrients and water – Aeroponics plants need less nutrients and water on average, because the nutrient absorption rate is higher, and plants usually respond to aeroponics systems by growing even more roots.
Mobility – Plants, even whole nurseries, can be moved around without too much effort, as all that is required is moving the plants from one collar to another.
Requires little space – You don’t need much space to start a vertical aeroponics garden. Depending on the system, plants can be stacked up one on top of each other. Aeroponics is basically a modular system, which is perfect for maxing out any limited space.
Great educational value – You can learn a great deal about plants from aeroponics. Kids especially will love having a small aeroponics system to grow a pet plant, without having to get their hands dirty.
Benefits of oxygen in the root zone:
Oxygen (O2) in the rhizosphere (root zone) is necessary for healthy plant growth. As aeroponics is conducted in air combined with micro-droplets of water, almost any plant can grow to maturity in air with a plentiful supply of oxygen, water and nutrients.
Some growers favor aeroponic systems over other methods of hydroponics because the increased aeration of nutrient solution delivers more oxygen to plant roots, stimulating growth and helping to prevent pathogen formation.
Clean air supplies oxygen which is an excellent purifier for plants and the aeroponic environment. For natural growth to occur, the plant must have unrestricted access to air. Plants must be allowed to grow in a natural manner for successful physiological development. The more confining the plant support becomes, the greater incidence of increasing disease pressure of the plant and the aeroponic system.
A variation of the mist technique employs the use of ultrasonic foggers to mist nutrient solutions in low-pressure aeroponic devices. Water droplet size is crucial for sustaining aeroponic growth. Too large a water droplet means less oxygen is available to the root system. Too fine a water droplet, such as those generated by the ultrasonic mister, produce excessive root hair without developing a lateral root system for sustained growth in an aeroponic system.
Key disadvantages of aeroponics:
Dependence on the system – A typical aeroponics system is made up of high pressure pumps, sprinklers and timers. If any of these break down, your plants can be damaged or killed easily.
Technical knowledge required – You need a certain level of competency in running an aeroponic system. Knowledge of nutrients amounts required by your plant is essential, because you don’t have any soil to absorb excess/wrong nutrients supplied.
Regular cleaning of the root chamber – The root chamber must not be contaminated, or else diseases may strike the roots. So you need to disinfect the root chamber every so often. Hydrogen peroxide is often used as disinfectant.
High cost – Most aeroponics systems are not exactly cheap. Aeroponics systems may cost many hundreds of dollars each.
For long-term growing, the mist system must have significant pressure to force the mist into the dense root system(s). Repeatability is the key to aeroponics and includes the hydro-atomized droplet size. Degradation of the spray due to mineralization and clogging of the mist spray heads inhibits the delivery of the water nutrient solution, leading to an environmental imbalance in the air culture environment.
Atomization (>65 pounds per square inch (450 kPa)), increases the bioavailability of nutrients, consequently, nutrient strength must be significantly reduced or leaf and root burn will develop. Large water droplets on the roots are caused by the feed cycle being too long or the pause cycle too short; either one discourages both lateral root growth and root hair development. Plant growth and fruiting times are significantly shortened when feed cycles are as short as possible. Ideally, the roots should never be more than slightly damp nor overly dry. A typical feed/pause cycle is < 2 seconds on, followed by ~1.5-2 minute pause- 24 hours 7 days a week, however, when an accumulator system is incorporated, cycle times can be further reduced to < ~1 second on, ~1 minute pause.
In most low-pressure aeroponics gardens, the plant roots are suspended above a reservoir of nutrient solution or inside a channel container connected to a reservoir. A low-pressure pump delivers nutrient solution via jets or by ultrasonic transducers, which then drips or drains back into the reservoir. As plants grow to maturity in these units they tend to suffer from dry sections of the root systems, which prevents adequate nutrient uptake. These units, because of their low cost, lack necessary features to purify and sterilize the nutrient solution, and adequately remove, debris, and unwanted pathogens. Such units are usually suitable for bench top growing and demonstrating the principles of aeroponics.
Simple 5-gallon bucket or tote aeroponic system:
One 5 Gallon (~20 liters) bucket or tote with a lid
One ½ inch by 12 inch cut-off threaded poly riser
One 360 degree ½ inch plastic head threaded with sprinkler heads
One hydroponic pump which can power 317 gallon per hour (or equivalent), also ½ inch threaded
One electrical timer with 30 minute increments
Several hydroponic net pots with lids, preferably made of foam rubber; The number of lids depends on the number of plants you want to hold in a single bucket.
Aside from the materials which are used in building the simplest aeroponic systems, here’s a list of tools you will need for assembling the system.
A saw to cut the poly riser, doesn’t have to be an electrical saw – a hack saw will do the job;
One sharpie marker;
Hole saw – sized for desired net pots. If using 3″ net pots, use a 2 7/8″ or 2 3/4″ hole saw;
Electric drill to drive the hole saw;
Step by step guide:
Cut the holes in the bucket or tote lid.
Take your hole saw and cut several holes in the bucket lid, depending on how many plants you will grow in that one bucket. You can do one to five plants per bucket.
Insert the net pots:
Place the net pots into the freshly drilled holes you just made on your bucket lid.
Put one net pot in each hole on the lid, and push the lid down on the bucket. Make sure the net pots fit snugly.
Setting up the pump:
Carefully screw the threaded poly cut-off riser onto the hydroponic pump outlet and place the pump on the bottom of the bucket. Make sure you cut the threaded riser to the desired height and add a threaded 360 degree sprinkler head.
Hydro pumps with suction cups are the best way to make sure your pump will stay in one spot.
Run the pump plug through one of the net pot holes and plug it into the timer. Always set the timer for 30 seconds on and 10 minutes off as that will be your watering periods during which the roots will take in water and nutrients, and then subsequently dry off and air out.
Fill with at least 2 gallons of water (about 8 liters), place your plants and grow media in the net pots and let the growing begin!
Make sure the plants get plenty of bright/sun light — that’s it – wait 30 to 60 days to harvest and enjoy.