Most of us have heard the term hydroponics before, but what does it actually mean? According to the dictionary, hydroponics is the cultivation of plants by placing the roots in liquid nutrient solutions rather than in soil. Furthermore, if we break the word into two parts, we have hydro and ponics. Both come from Greek origins, with hydro referring to water and ponics from the word ponein meaning “to labor or toil.” With that being said, hydroponics can be used just about anywhere and with multiple types of plants. In fact, there’s a lot of fruits and vegetables grown in hydroculture systems! Whether it’s a leafy green like lettuce, kale, or spinach to a juicy fruit like strawberries, tomatoes, or blueberries, it can be productively grown without soil!
Even though it may appear to look like one long pot of soil, but these strawberries are planted in an artificial growing medium.
But wait, don’t all plants need soil?
Actually no, plants don’t need soil. Soil is highly beneficial to plants by providing structural support for the roots as well as a substrate to exchange nutrients on, but this can be achieved through various materials. Try thinking of it this way – a plant has W.A.N.T.S. Water, Air, Nutrients, Temperature, Sunlight. With only a single one of these elements missing, a plant cannot survive. For example, if there’s a drought, eventually the plant will lose too much water through transpiration and will wilt and die. But what about if the temperature is too hot or too cold? The plant could easily burn or freeze, which quickly ceases its productivity. And what if a plant is grown in an environment lacking carbon dioxide? The plant wouldn’t be able to continue photosynthesizing, which means there are no sugars being produced. In a hydroponics system, the crops are receiving proper amounts of water, air, nutrients, temperature, and sunlight!
Now that we’re all wondering about hydroponics, it’s time to dive a little bit deeper! There are six main types used in large-scale production systems.
Let’s start off with one of the more simple hydroculture methods. A wick system, or more commonly referred to as wicking, is when a plant is growing in the top of a material that is partially submerged in the nutrient solution. This material (it could be cotton, perlite, vermiculite, rockwool, etc.) is absorbing the liquid at the bottom and wicking it upwards towards the plant. This process means the plant’s roots are not wholly submerged in the water, which minimizes the associated risks and chances of this system failing. There are only four main components needed to create this system: wicks, growing medium, a container for the plant to grow in, and a holding container for the nutrient solution. This could easily be done in a classroom or around the house for a little innovative fun!
This picture shows a very simple wick system, one that uses a cotton string to bring nutrient solution to the perlite growing media. Photo from ehow.
Nutrient Film Technique (NFT)
In a nutrient film technique system, there is a constant flow of nutrient solution over the roots of the plant. This greatly differs from wicking because the roots come in direct contact with the water. One of the biggest risks associated with this system is the chance of drowning out the roots. Due to this, it’s important to ensure the roots are receiving an ample amount of oxygen, whether it be from the air or an air pump in the water. The most efficient and productive NFT systems only submerge the root tips in the water, which means the remaining surface area on the roots are able to breathe. There are a few more components in this system, which makes it a bit complex and complicated. There’s still a reservoir for the nutrient solution and a growing media (perlite, vermiculite, rockwool, etc.). Additionally, there needs to be a channel for the water to run down, an air pump, a water pump, and a return pipe to complete the cycle.
This is lettuce grown with NFT. You can even see some algae growth that can accumulate if not cleaned often enough.
Deep Water Culture (DWC)
In this system, the plant’s roots are also coming into direct contact with the water, but it’s not constantly flowing over them. In a simplistic view, DWC is very similar to wicking, just without the wick. The plants sit in a growing media at the top of the reservoir container, and the roots grow downward to reach the water. The most important and vitally crucial aspect of this system is the air pump. Without an air pump, the plant would take up all the available oxygen in the water solution and essentially suffocate. This air pump allows for continuous oxygenation and really serves as the heart of deep water culture. The best management technique would be to clean out and refill the tank about once a month, or frequent enough to prevent algal growth.
Ebb and Flow (Flood and Drain)
Ebb and Flow is my favorite system, simply because of how autonomous it can become once properly set up. In this structure, there is a generally larger reservoir tank which is pumped into a growing bed that holds plants. Instead of letting the water sit and suffocate the plants, it will drain back down into the water tank. This is controlled by a timer and can easily be scheduled for the right frequency and duration of each flooding event. The plants sit in a growing media such as peat moss or rockwool, which absorbs the nutrient solution for extended periods of time. To make your own ebb and flow system, you’ll need a tank for the nutrient solution, a water pump, a growing bed that can be flooded, growing media for the roots, and tubing for the uptake and return pipes. Once this is completed, it should look something like the picture below! This is another great example of cycling water and nutrients through a system!
The idea behind a drip system is quite similar to that of ebb and flow. The only major difference between the two is that instead of flooding the growing bed from the bottom up, there are small irrigation pipes that provide water from the top of the growing media on downward. This particular cycle still needs a pretty decent sized reservoir to hold the nutrient solution, an effective water pump, a growing bed to hold and drain water, as well as tubing to complete the cycle. Additionally, the grower needs a drip emitter, or at least a pipe with minuscule holes to allow for water to escape the tubes. This water pump can also be set up to a timer, which allows for minimal day-to-day upkeep. The grower can accurately control the quantity of water, nutrients, pH of the solution, and air available to the plants and their roots.
Wait a minute, the prefixes aero and hydro mean two completely different things! How can aeroponics be considered a type of hydroponics? An aeroponic system still has the main components of every other type of hydroculture system, which includes exposing the roots to a nutrient solution without utilizing soil. When using an aeroponics setup, this allows for the most oxygen exchange with the roots since they are never fully submerged underwater. After learning about the five previous systems of hydroponics and how they work, you can probably guess the similarities and differences in this specific one! Instead of flooding a growing bed or utilizing a drip emitter, the nutrient solution is distributed through misters. These misters are positioned beneath the roots and growing media, and when turned on will coat all surfaces in a thin film of water droplets. This method still provides the necessary nutrients and water to the plants, without taking away any of the other W.A.N.T.S. The similarities include the basics of most hydroponic systems: having a good sized tank for holding the water solution, a growing bed and medium for the plants, a working water pump, as well as small tubing to connect everything.
I’d love to give you all recommendations on which system works the best and some specific management techniques, but alas I’m still learning in those areas. Some important takeaways are:
- Plants can be grown without soil, but still need a medium to exchange nutrients on.
- Hydroponics can be used in many situations, from commercial fruit production to explaining simplistic ideas in a classroom setting.
- Each system is not necessarily a ‘one size fits all’ scenario. It may take time and practice to perfect your system for a particular plant!
P.S. If any of you have experience growing hydroponics or a preferred system that works better than others, feel free to share it in the comments!