Can plants be grown with just fog? Absolutely yes! Read more about this eco-friendly method to produce food.

What is Fogponics?

Fogponics is a plant growing method when the roots of plants are hanging in water and nutrient aerosol generated with ultrasonic foggers.

Some industry experts and scientists do not separate aeroponics and fogponics as different methods or techniques of growing plants. In their eyes any form of growing plants in aerosol is considered aeroponics which is then differentiated into low pressure aeroponics, high pressure aeroponics and ultrasonic aeroponics. With the classification questions explained, let‘s dive into fogponics – ultrasonic aeroponics.

Fogponic systems only use nutrient-rich fog to feed plants. The idea is based on hydroponic systems, in which the roots are kept in a soilless growing media, such as coco coir, rock wool, pieces of foam, etc. And nutrient-rich water in the form of fog is misted over the roots on interval or regular basis. In fogponics, the growing medium is simply eliminated, leaving the roots to dangle in the air and be occasionally puffed by fogging devices that were specifically created for the purpose.

In systems that use fogponics, seeds are “planted” in pieces of rockwool or foam that are crammed into tiny pots and exposed to light and nutrient fog on opposite ends. As the plants develop, the rockwool also secures the stem and root mass.

How does fogponics work?

As mentioned above, the basic principle of fogponics or ultrasonic aeroponics is feeding water and nutrients to the roots of plants or seedlings in a form of fog (aerosol). So the plants or seedling are being placed on a tray or foam above a reservoir with ultrasonic fogger submerged in the water nutrient mix. These ultrasonic foggers work the same way as home humidifiers do. So, when the ultrasonic fogger is turned on, the liquid water fertilizer mix is converted into fine fog. This fog has the water droplet size of 1 to 10 microns, which makes it almost gravity defying and easily dispersible. This way the fog can travel, surround and penetrate all spaces around root systems, fully cover the roots. This method is quite simple and works in practice, so why is it not used on a missive scale? To understand this we must look at advantages and disadvantages of fogponics – ultrasonic aeroponics.

Advantages of Fogponics

No root disease

Root disease is a big problem for hydroponic farmers. If one plant in the production line gets it – every plant does. Therefore, every year, globally, hydroponic farmers lose around 20% of their crops.

Since plant-to-plant contact is restricted in fogponic systems and each fog pulse can be sterile, fogponics helps reduce the spread of root disease. Root disease can spread across the growth medium in the case of soil, aggregate, liquid, or other media, affecting numerous plants. These types of media typically need to be sterilized after each harvest, and quite often farmers choose to just throw away used media and replaced it with new, sterile media.

If a single plant does get root or any other disease, it may be easily removed from the growing system without upsetting or infecting other plants, which is a distinguishing benefit of fogponic technology.

When compared to more conventional means of cultivation (hydroponics or soil), many plants can grow at a higher density (plants per square meter) thanks to the disease-free environment provided by fogponics.

Healthy roots on the left and Diseased roots on the right

Fine fog – tiny droplets

According to NASA research – Aeroponics for Spaceflight Plant Growth by J.M. Clawson, A. Hoehn, L.S. Stodieck and P. Todd BioServe Space Technologies R.J. Stoner 2000, tiny micro droplets don‘t really encroach on roots. That‘s why ultrasonic aeroponics / fogponics is so good, almost perfect for cloners. Because the clones – cuttlings and/or seedlings are still underdeveloped, thefore weak and fragile, this method of using low pressure fog shall not harm the clones and roots.

Furthermore, talking about cloners, fogponic water droplets are small sized by nature – it‘s a fine mist. That means that the water droplet, by default, cannot contain too many nutrients, which is extremely important for clones, cuttings, and seedlings as they need little amount of nutrients, too much of fertilizer could burn the developing roots.

More oxygen in the root zone = faster growth and bigger plants

Who thought that bare roots could endure, much less flourish?

For a plant to grow properly, oxygen (O2) must be present in the rhizosphere (root zone). So, almost any plant may mature in air with an adequate supply of oxygen, water, and nutrients. As fogponics is done in aerozol – air mixed with micro droplets of water with dissolved fertilizer, it is a perfect method to grow plants.

Fogponics are superior to hydroponics on this issue because oxygen solubility in water has a natural limit, when in aerosol environment there is more oxygen than needed by the plant.

Some farmers prefer fogponic systems over other hydroponic techniques because the increased aeration of the water nutrient solution provides more oxygen to the roots of the plant, therefore enabling faster and better metabolism, stimulating growth and preventing formation of pathogens.

I. Aeroponically grown II. Hydroponically grown III. soil grown

Even nutrient distribution

In fogponic systems nutrient distribution is even, unlike in some hydroponic systems. In ultrasonic aeroponics all plants get the water and nutrients in the form of fog at the same time. For example, in some hydroponic systems like NFT the water cycle starts witch one nutrient concentration, but as the liquid medium flows through the system, the nutrient concentration changes. That is because plants that sit in front of the system receive the most nutrients, the second row gets less, the third row even less than the second and so on. Plants located at the end of the system receive the least nutrients because of this flawed design.

Better nutrient uptake - less water and fertilizer

Fogponically grown plants spend majority (around 99.98%) of their time hanging in the air and very little (around 0.02 %) time in direct contact with water nutrient solution that has been converted into aerosol. The ultrasonically atomised water and nutrient fog makes a major contribution to the roots’ efficient oxygenation The roots are able to absorb oxygen more effectively because of the period spent without water. For contrast, fogponics has a throughput of around 1.5 milliliters per minute, nutrition film technique (NFT) has a throughput of 1 liter per minute.


The amount of nutrients needed for plant development is decreased as a result of the decreased nutrient throughput volume.
Unfortunately that‘s not always the case. A lot of attention, observation and care has to be given to achieve proper oxygenation and nutrient throughput in fogponics, we will talk about this later when discussing disadvantages of ultrasonic aeroponics.


Furthermore, with having to discard the low amount of liquid solution or without having to rinse out the growing matrix in which the roots had previously been submerged or embedded, a range of different nutrient solutions can be supplied to the root zone utilizing fogponics.

Easier to clean

Fogponics / Ultrasonic Aeroponics usually has one or very few fog generator – ultrasonic misters. That means the grower has less atomisation units to clean compared to low and high pressure aeroponics.

Disadvantages of Fogponics

Fertiliser salt build up

Just like in aeroponic systems, over time you will notice fertiliser salt build up within the fogponic growing equipment too. High pressure aeroponic nozzles clog up with these salt particles and it results in system failure, then loss of crops. Similarly, fogponic ultrasonic misters also clog up with these fertiliser salt sediments and stop working, generating the fog that your plants desperately need. To avoid system failure and crops drying out, the grower has to constantly check on this issue and regularly clean the ultrasonic foggers. It‘s and easy task, because the cleaning is done with something similar to a toothbrush or soaking the fogger in weak acid. Nevertheless, it is a constant headache and a repetitive task, that requires time and labour.

Cracking

Fogponic equipment is flawed by design. The way ultrasonic foggers work is relatively simple. The piezoceramic disk or membrane receives electricity at a certain frequency and the micro crystals inside piezoceramics expand and retract accordingly. In other terms, it vibrates at this high frequency, and it ruptures the molecular bonds between water molecules – converting water liquid into water gas – fog. So if the piezoceramic disk or membrane cracks, and that happens more often than not, the equipment stops working, doesn’t generate fog and your crops die.

Electricity dependency

Fogponics as any other advanced irrigation method of hydroponics, cannot operate and run without electricity. Keep in mind that the roots of the plants are hanging in fog, not submerged in hydroponic liquid. So, in case of a power outage the system will stop working, there will be no more fog – no moisture and fertiliser, then the roots of the plant will dry out and the crops will die.

Heating of the water nutrient mix

Ultrasonic foggers are very inefficient in terms of energy use. Only about 10% of the electricity used is converted into vibrations that generate fog. The other 90% of the energy ends up as heat. This is very important and BAD. As this heat transfers into the reservoir, it heats up the water nutrient mix. Any experienced grower will tell you that the roots of the plant are more sensitive to temperature than the upper part of the plant. Also, in most cases the roots require lower temperatures than the leaves. So, you can clearly see that overheating the nutrient water solution is another headache that comes with fogponics.

Droplets too small

It has been noted by many scientists and growers that water droplet size of 20-30 microns is the best for the plants. Fogponics generate fine fog with water droplet size of 1-10 microns. This extremely small size of the water droplets results in high surface tension of the water droplet which makes it hard for the droplet to stick to the roots. Sometimes this fine or dry fog provokes the plant to develop an abnormal amount of secondary roots. So instead of growing it’s leaves, the plant is desperately trying to survive and develops a bunch of useless roots. These droplets with the wrong physical properties may also form a film on the roots and inhibit oxygen intake, so the possibility of choking the plant arises.

Fogponic roots

Expensive and Difficult to maintain

Even though fogponics drastically reduces your water and fertilizer needs, it is still an expensive operation to run. These high tech growing systems require quite expensive equipment that requires a lot of energy. The design of fogponic systems also differs from the hydroponic ones because the nutrient water aerosol must be contained within the system, the roots have to be protected from light exposure, etc. This results in more complicated structure, more materials, more costs. The maintenance of complicated structure isn‘t easy and solving fertiliser salt build up, piezoceramic disk cracking, overheating nutrient mix problems is a constant difficulty.

How to fix/solve fogponic problems?

Fogponics 2.0
Baltic Freya Fogponics 2.0 Fog Generator

Baltic Freya has developed Fogponics 2.0 fog generator that doesn‘t clog or crack. Our mist generators look like nozzles, but require no high pressure. It‘s efficient energy design doesn‘t overheat the nutrient solution. The water and nutrient delivery hole within our fog generators is millimeters wide and it vibrates. We tried to purposely clog it by adding sand, by adding glass shards to the water nutrient solution and we failed to clog it. Baltic Freya Fogponics 2.0 fog generators can and do deliver the correct water droplet size of 20-30 microns. But if you wish for a different one – Baltic Freya fog generators are tunable, they can generate water droplets varying from 5 to 60 microns.

Conclusion

Fogponics is a relatively new and novel technique to grow plants. This technology presents numerous benefits compared to soil or hydroponic farming, but it also has serious flaws and problems. Baltic Freya has solved these problems and improved this growing technique, click here to read more about Fogponics 2.0 fog generators.

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