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Hydroponics is an advanced form of farming that uses water and a liquid nutrient solution to feed the plants. Instead of soil, an inert growing medium is used. Depending on which system is used, the roots are exposed to this nutrient solution. The plants receive everything they need to grow: sunlight, oxygen, nutrients and water. The plants are often suspended in net pods with an inert growth medium, such as rockwool or coconut coir.
Hydroponics was first coined by a man named Dr. William F. Gericke. He showed the world the potential of hydroponics by growing 25 foot high tomato vines using only water and nutrients in 1925. Since then, hydroponics has become more advanced. NASA uses hydroponics on the International Space Station to provide astronauts fresh produce!
Benefits and Downsides
Hydroponics has numerous advantages and some disadvantages compared with regular soil based gardening.
No soil-based diseases
By getting rid of soil and lifting the system off of the ground, hydroponic systems get rid of soil based pests and diseases. This can lead to a much simpler growing process for experienced hydroponic growers [Epic Gardening].
Quicker Growth
Because the roots hang in a growth medium, they have more access to oxygen compared to soil gardening. Since the roots do not need to compete for space, plants can concentrate more on growing the plants. Therefore, hydroponically grown plants often grow up to 25% quicker compared to soil based plants. Hydroponic systems are often found in greenhouses and are also used in high tech vertical farms.
Lower Water Use
Hydroponics does not require good quality soil, making it easy to grow in places with bad soil conditions. All you need is access to water and electricity. Because the water gets recycled in most hydroponic systems, water usage is much lower than in soil based farming. Up to 82% less for hydroponics and up to 95% less for aeroponics [Wikipedia]. Growing 2.2 lbs/1 kg of regular tomatoes using intensive farming practices requires 110 US gallons/400 L of water. If growing hydroponically or aeroponically, only 18.5 US gallons/70 L or respectively 5.3 US gallons/20 L of water is used! That has the potential to be very disruptive if the price of water increases in the future!
Total Growing Control
Another benefit is that the grower has total growing control. This is because the nutrient solution put in the water can be customized to the types of plants you are growing. However, because the system often uses one reservoir, this limits the different types of plants you can grow at the same time.
Downsides
Soil acts as a natural buffer for any potential growing errors. Hydroponics, since it does not use soil, does not have this natural buffer. If you make a big mistake in a hydroponics system, this will have a bigger negative effect on the plants you grow. A beginner may have an easier time off starting in a soil based system.
Types of Hydroponic Systems
Next, we’ll go through some of the different types of hydroponic systems available.
Kratky
The Kratky system is the simplest hydroponic setup, consisting of a bucket of water, one or two net pods and a lid. It has space for one to two plants, but has limitations to the productivity. Once you have the system setup, you fill water until it covers a third of the net pods. The Kratky system is self watering and self oxygenating because the plants drink water and create air pockets in the tank. Maintenance wise, you only need to adjust the pH (keep between 6 and 6.5) and add a nutrient solution [VerticalRoots.com].
Wick
Another simple system is the wick system. Above is an example that uses three pots, each with a nylon wick that transports the water from the reservoir below to the plants above. Normally, a growing medium that is good at absorbing water is used (e.g. perlite or vermiculite). Although it is a simple system, there is a limit to how many nutrients the plants can receive. It is very useful for small herb gardens and small plants in general, but will not work for larger fruit bearing plants such as peppers and tomatoes. Also, the water and nutrients are not absorbed evenly in a wick system. This can lead to toxic mineral salt buildup, making it important to flush the pots with water from above every one to two weeks [Sensorex.com].
Deep Water Culture
Deep water culture (DWC) is similar to the Kratky system, but uses an air stone or an oxygen pump to deliver oxygen to the plant roots. It is more easily customizable than Kratky and can support a broad group of plants. It is simple and requires little space. Root rot can occur if not enough oxygen is delivered to the plants [VerticalRoots.com]. Like the Kratky system, it is important to provide nutrient solution and make sure the water pH stays at an acceptable level.
Nutrient film technology
Nutrient film technology (NFT) also lets you customize the inputs to optimize growth, like DWC. It is harder to setup compared with DWC and requires more money and time to maintain. The reservoir with the nutrient solution gets pumped up to a channel where the plants are located in net pods. The tiny film of nutrient solution then flows back down into the reservoir, where it then gets pumped back up. Like other hydroponic systems that require a pump, if there is pump failure, your plants will die quickly [VerticalRoots.com].
Ebb and Flow
Ebb and Flow is a similar system to NFT, is just as customizable, but requires slightly less electricity than NFT. This is because ebb and flow will flood the plant channel every once in a while and then flow back down to the reservoir. Hence the name ebb and flow. Just like NFT, ebb and flow requires some know how to setup the automation [VerticalRoots.com].
Drip irrigation
Drip irrigation is a flexible system that can fit most spaces and is highly customizable to one plant or many plants. It requires some more maintenance if you want to recycle the water in the reservoir. It requires two pumps, a reservoir and hoses to move the water around. The air pump keeps the water solution moving and oxygenated. The second pump is used to pump around water to feed the plants. The plant roots are embedded in a growth medium because water drips through the growth medium to the roots. This system works best by sprouting seeds first (e.g. with coconut coir). Then, the bigger plants are put into a more porous growing medium like vermiculite [VerticalRoots.com].
Aeroponics
Aeroponics is one of the most advanced forms of hydroponics, but also has the greatest potential for water savings. In aeroponics systems, the reservoir pump pumps water through pipes to one or many misters. This creates a fine mist that is sprayed onto the plant roots. According to research, most plants best absorb particles in the 1-50 um range (i.e. very small). The advantage of aeroponics is that the roots have more access to oxygen. This is because the water molecules are smaller compared with hydroponics. More oxygen at the roots lets the plants grow quicker. Like shown above, aeroponics uses even less water than hydroponics. One of the main disadvantages of aeroponics is the mister nozzles can get clogged after a while and need consistent maintenance. To mitigate this, I would like to focus shortly on a subset of aeroponics, fogponics.
Fogponics
Fogponics uses an ultrasonic mister to create fog vapor droplets usually less than 10 microns in size. The droplets are even smaller than aeroponics, allowing the roots even more access to oxygen. This system works really well with seedlings and clonings. It also works with with green vegetables and herbs. Maintenance wise, it is easier to maintain than aeroponics because only one atomizer is used, not multiple mister heads. The atomizer can heat up the reservoir, so it is important to use a timer that turns the atomizer on and off at regular intervals. Salt will also accumulate that can clog the atomizer, which is why the atomizer should be cleaned at regular intervals.
Summary
All hydroponics systems have their advantages and disadvantages. The simpler systems described are easier to setup, yet do not offer the same level of control over the growing process. Since water is recycled, each hydroponics system uses much less water compared with soil based gardening. Yet, since pumps are being used, any pump or electricity failure can be detrimental for the plant growth.
But, I firmly believe the positives outweigh the negatives. With a bit of work, most people can setup their own DIY hydroponics system and get started quickly. If one is not DIY inspired, there are some great hydroponics kits one can buy.
I would recommend the Aerogarden Sprout, a DWC system that has integrated LED lights. This system is perfect for beginners and lets beginners grow plants all year around.
Hydroponic systems are often used together with grow lights to speed up growth even further. Feel free to read more about grow lights in the Best LED Grow Light Brands and the LED Grow Light Glossary posts.
