The important thing with trying out new methods of gardening is to be aware of the risks. The saying, “with great risk comes great reward” applies here. If you give your plants and their roots the environment they want, aeroponic systems can be wildly successful.
Growing plants in an aeroponic system is simple if certain environmental parameters are met. For example, if your water temperature never reaches above 64°F, bad biology and enemies of aeroponics such as algae and root rot can hardly begin to grow, much less thrive.
Maintaining your water temperatures below 64°F requires keeping ambient room temperatures below 72°F, and this can be quite a challenge, especially in the summertime. A water chiller may be necessary to keep the reservoir cool.
You may also need to invest in air conditioning or more efficient lighting to shield the root chamber from the heat caused by some grow lights. Many unseasoned aeroponic growers overlook these steps and accidentally allow their roots to cook in between spray cycles.
They eventually notice the plants are struggling with early stages of roots that have likely contracted water molds such as pythium or phytophthora. These problems are also commonly found in hydroponic systems when water temperatures are not kept at reasonable levels.
However, because aeroponic roots are dangling in the air with no medium to provide an advantageous microclimate where evaporative cooling can occur, aeroponic systems are much more susceptible to pathogen problems. It’s time for some troubleshooting.
If plants begin to slow down in growth and vigor, this is the first sign you need to pay closer attention to what’s going on. When plants look like they are suffering, there is likely a problem with the environment, pathogens or pests. Take a look at your growing environment first.
What are your temperature and humidity levels? Are these parameters providing plants with the environment they need to grow? What works with soil, soilless or hydroponic gardening may not work as well with aeroponics since roots are exposed and hanging in the air.
The growth chamber is under a light and can be heated up even more than the surrounding air. For this reason, reservoir temperatures must be kept lower so the water can cool the roots when they are sprayed. Roots are typically misted every 1-4 minutes so they can be kept at the proper temperature by the cooler water in the reservoir.
Spraying roots with an aeroponic system will help avoid root aphids, fungus gnats and so on from laying eggs on the roots in the mist pattern, but aeroponics does not completely prevent these types of pests.
They will still find ways to reproduce in an aeroponic system by finding areas to lay their eggs that are safe from the spray. Be on the lookout for common growroom problems, but keep a close eye on the roots.
They need to be healthy and thriving at all times to maximize the benefits offered from aeroponics.
Discoloration can occur when using certain nutrients that are slightly tinted, such as humic or fulvic acids and organically mixed nutrients.
For this reason, color is not a reliable indicator of root health and vigor. Observe the ends of the roots to verify they are healthy and growing new tips. In addition to browning, rotting roots will develop a slimy coating and immediately lose their vigor.
Clogged nozzles are perhaps the most common problem associated with aeroponics. Fortunately, they are completely avoidable. Clogged nozzles result from the infrequent cleaning of filters, pumps, tubes and fittings.
Another common culprit is allowing the system to dry out after harvesting and before cleanup, which leads to nutrient salts accumulating on the inside of the plumbing. When the system is turned on again, these salts break apart and the solids can easily block the nozzle’s orifice.
Likewise, nozzles will often clog before harvest time if the filter is not kept clean. Clean the filter in between sprayings, or temporarily power off the pump, leaving the filter assembly submerged to prevent air from entering the lines.
Maintaining a Healthy Aeroponic System
Maintaining a healthy aeroponic system can be achieved by keeping a sterile reservoir and grow system, or by inoculating and maintaining a population of beneficial biology into the reservoir and grow system. Both of these methods will maintain a healthy system even though they are virtually opposite from one another.
In a sterile system, growers use hydrogen peroxide, enzymes or other similar products with their nutrient mix or in between feedings to keep things clean. On the other end of the spectrum is the inoculation of good biology to prevent the bad biology from getting started.
When there are beneficial fungal spores and bacteria present, they compete with the bad bacteria for the same food. They can easily take a strong hold and prevent the bad biology from ever growing.
Whether you’re using a sterilization method or inoculating with good biology, the bad biology must be kept at bay one way or another. If it is not, it is only a matter of time until the system is contaminated and plants begin to suffer. This is why it is extra critical to maintain correct water temperatures and prevent the kind of environment bad biology can thrive in.
Cloning Using an Aeroponic System
To have consecutive successful runs in an aeroponic cloner, you need to thoroughly clean the cloning system in between each run. The cleaning process is often overlooked and a likely cause of most problems.
Over time, neoprene inserts begin to accumulate unwanted pathogens and should be replaced. Another thing to pay close attention to is water temperature. As mentioned previously, bad things grow in water above 64°F.
Internal pumps often overheat the water, so use a timer to allow the pump to cool. Be sure the area surrounding the stems where the roots will eventually grow is kept relatively humid.
Another easy way to cool down your submersible-pump system is to add frozen water bottles, which act as ice cubes to cool the water.
There are also more technical options, such as external high-pressure aeroponic pumps and misting nozzles, which allow for further control of the fine water droplets as they are delivered to the fragile cuttings.
During aeroponic cloning, the stems must be kept wet to allow for proper root development. As roots develop, you should be increasing your spray times.
After roots are 3-4-in. long and have begun to branch out, dialing back spray times will allow for increased root development, as well as prevent problems arising from root rot, which is usually brought on by overwatering.
Growing Until Harvest
Growing plants for extended periods of time in an aeroponic system is often challenging. Just as plants can grow more rapidly, things can also take a turn for the worse more quickly when compared to other methods of growing.
In other words, plants perform better when things are going right but are far less forgiving when things go wrong. For this reason, many aeroponic gardeners use the sea of green (SOG) method, which means they prefer growing small, uniform plants that make up what looks like a sea of green.
Growing shorter plants allows for faster crop turnover, further accentuating the benefit of increased growth rates achieved by aeroponics.
Whether you’re growing small or large plants, aeroponically grown plants must be pampered and remain happy throughout the entire process to maximize yield and quality. Many expert aeroponic growers will reduce their spray times to mimic nature and seasonal changes.
For example, in the early stages of growth, growers are mimicking the springtime, as plants want more water. As vegetative growth occurs more rapidly, the plants will have increased transpiration rates, requiring more water.
Later in a plant’s life cycle, it will begin to drink less water. Notice how in late summer and early autumn there is typically less rainfall than there was in the spring?
The plants are now ripening and not growing as aggressively as before. So, spraying the roots for shorter ON times and keeping the same OFF times, or perhaps even slightly increasing OFF times as the harvest begins to ripen will provide plants with the moisture they need and prevent issues that occur with overwatering.
Low-pressure aeroponic (LPA) systems use submersible, pond-style pumps that move a large volume of water at a low pressure. Usually these set-ups use 360-degree spray nozzles and a manifold. Some LPA systems use a sprinkler-style product made of tubing with holes cut in it.
Critics of LPA call it a version of nutrient film technique or shallow water culture, a.k.a. recirculating hydroponics. In a way, each comparison is true, but this style of growing is indeed aeroponics. After all, there is minimal amounts of medium in the small net pots, which only act as an anchor for the plant. Roots are still hanging in the air within the root chamber and being sprayed with water.
High-pressure aeroponics, a.k.a. fogponics, uses external pumps that create a fine mist and much smaller water droplets. These droplets are in the 30-80-micron range—the ideal size for nutrient delivery, as determined by NASA researchers aboard the International Space Station during their experiments growing aeroponic potatoes in the late ’90s. Misting cycles are more precisely controlled with repeat cycle timers to provide roots access to more oxygen.
Fine hairs called trichoblasts appear off the spider webs of roots, increasing their surface area and nutrient-uptake capabilities (see “Aeroponics 2.0” in Maximum Yield, November 2015).
Critics note that if systems are not maintained, nozzles often clog and high temperatures cause the most stress in high-pressure systems when compared to other aeroponic systems. Following the proper cleanup procedures and setting yourself up for success will address these challenges and provide the full benefits of this system.
Cleaning an Aeroponic System
Probably more so with aeroponics than any other style of growing, the cleanup process is of vital importance. Successful hydroponic growers know that cleanliness is godliness, and in aeroponics, this statement is definitely true since problems such as diseases, pathogens and unwanted biology can occur more frequently.
With aeroponics, everything happens faster, including problems. This is why it is so important to properly clean your gear after each harvest.
After removing plant material and debris, clean the room thoroughly. Sweeping, mopping and spraying off the walls with a light bleach or peroxide solution is good practice. Next, all the gunk needs to be removed thoroughly from the system and the reservoir.
You’ll need to apply a bit of elbow grease for this step. It is also important to clean the tubing, nozzles, manifolds and pumps. A good method is to run hot water with hydrogen peroxide through the system, which purges it of any growth inside the lines. After the system is free of nutrient buildup and other debris, repeat this process at least one more time to ensure the system is completely flushed, and then power down and let the system dry out.
In controlled environment agriculture, growers must manipulate as many parameters as possible to maximize crop performance. Aeroponics offers cultivators more controlled nutrient and oxygen delivery than any other style of growing.
Although aeroponics may require more maintenance and attention to detail, the potential for increased efficiency, quality, yield and growth rates makes it a fun, rewarding gardening method with a bright future.