Aeroponics: A Blooming Good Way To Grow Plants Without Soil
Aeroponics: A blooming good way to grow plants without soil
During the early 1600s, some theories speculated that soil is just there to hold up the plant and others suggested that plants “eat” the soil to grow. Flemish physician Jan Baptist van Helmont (1579-1644) wanted to test these ideas by isolating the soil, so he added 200 pounds of dried soil to a container and then planted a willow tree weighing five pounds. This became known as the willow tree experiment and is widely acknowledged as the first quantitative investigation into plant nutrition.
The tree was watered regularly and continued to grow happily. After five years, Van Helmont uprooted the tree to weigh it again and established that it was now about 169 pounds. He also dried the soil to weigh it again and found that it was just under the initial weight of 200 pounds. He concluded that 164 pounds of wood, bark and roots were grown from water alone.
Today, we know that this is not accurate and that plants absorb nutrients from the soil. To test his hypothesis, Van Helmont should have rather used water as his soil medium. This occurred to John Woodward, and in 1699 he published his hydroponic experiments with spearmint in which he concluded that earth and not water account for growth in plants.
His conclusion was based upon experiments in which he grew spearmint in glasses containing water from various sources. He noticed that improved growth can be achieved by adding a bit of healthy garden soil to the water.
Fast-forward a few centuries, and we are still fascinated by the possibility of growing plants without soil. In 2020, the international hydroponics market size was valued at USD 2.1 billion, and last year, the global aeroponics market reached a value of USD 824.77 million. And with double-digit growth rates, these markets are not slowing down anytime soon.
Hydroponics vs aeroponics
Both these methods are water-based systems that don’t need soil to grow plants. The main difference between these two methods is the way nutrients are delivered to plants. With hydroponics, the roots are submerged in water, whereas, with aeroponics, the exposed roots are misted on a regular basis.
By exposing the roots to the air, oxygen is delivered directly to the roots boosting nutrient uptake and resistance to pathogenic fungi. Everything that can be grown with a hydroponic system is also suited to aeroponics.
The benefits of aeroponics
- Increased yields
- Speedy growth
- Nutrient-dense produce
- Uses less water (98% less according to NASA)
- Vertical designs save space
Aeroponics: How to get started
Most aeroponic systems are towers with a reservoir at the base and a pump to help get the water to the top. If you have the budget, you can buy modular towers that are pretty much plug-and-play. Alternatively, you can use containers you might have around the house, think a bucket or plastic tote with a lid. Even a PVC pipe with a decent diameter can be modified to serve as a growing tower.
This video shows how simple it is to create an aeroponic system with buckets, and in this one, a PVC pipe is used. Here’s another example of an aeroponic tower built with materials that are easy to source.
The drawbacks of aeroponics
Aeroponic systems require regular cleaning: Minerals can build up in the misters, and as with any high-moisture environment, it is the ideal playground for algae, fungi, and bacteria. Hydrogen peroxide is a great option to sterilise equipment.
A proper misting or sprinkling system will most likely require electricity to keep the pumps going. But if the power is out for too long, the dangling roots won’t get a regular spray of water and may rapidly desiccate. Luckily, with our climate, a solar-powered watering system can be a very practical and cost-effective solution. Just take a look at the Irrigatia C24 Solar Irrigation System.
Low- vs high-pressure systems
Most DIY aeroponic systems rely on a simple fountain pump to push water out of the reservoir and through the misters. This creates a light spray, like a sprinkler, and doesn’t create a fine mist. Professional aeroponic systems utilise pressurised water tanks to create a true mist to deliver nutrients more effectively.
Get the pH right
The pH scale runs from 0 to 14 and is logarithmic, essentially meaning that the difference in a single pH unit is about tenfold. pH describes the relative acidity or alkalinity of a growing medium. It is important to get the pH right because it affects the availability of nearly all essential plant nutrients. Most nutrients are widely available to plants within a pH range of 6.5 to 7.5.
A nutrient solution is a must
As Woodward’s work established: When you are growing plants in water, a nutrient solution is fundamental. Nowadays there are nutrient solutions tailored to every grower’s needs. For fruiting vegetables, herbs, and berries, try this. There is also this solution - specifically designed for leafy lettuce and leafy herbs like coriander, basil, dill, rocket, mint, etc. Boost the burn of your capsicums with this solution.
While growing with aeroponics is quite easy, the initial setup can be relatively costly. But if you want to grow food year-round and in a limited space, then aeroponics might be the system for you.
About the author
Gerda le Roux is a freelance copywriter with an unquenchable thirst for knowledge. She likes to think of herself as a budding botanist and her love for plants is contagious.
