I’ve had my hydroponic tower garden for a long time. This morning, as I was pruning tomatoes, a thought suddenly struck me. What if there was a better way to do this? I worried that I may have led too sheltered a life (hydroponically speaking!) and started to get curious about other methods of growing plants without soil. What other methods and techniques were out there to explore? It turns out, quite a lot.
There are eight different hydroponic techniques that can be used to grow plants without the need for soil. Each method works in a slightly different way and has its own pros and cons to consider. The main hydroponic types are as follows:
- Wick System Hydroponics
- Ebb & Flow
- Drip Hydroponics
- Nutrient Film Technique (NFT)
- Aeroponics
- Aeroponic/Hydroponic Towers
- Deep Water Culture
- Kratky Method
I was curious to find out more and so I started researching each of these methods to better understand them and to determine if I should use any of them myself to advance my hydroponic experience. Let’s take an in-depth look at each hydroponic technique and discuss the many advantages and disadvantages of each system. By the end, you will know which method suits your specific needs.
First, what actually is hydroponics?
Hydroponics is an increasingly widespread method of growing plants without the need for any soil. In a hydroponic system, plants are instead supported by an artificial substrate such as peat moss, rock wool, small stones or clay pellets. The roots are either suspended in or frequently washed with a nutrient-rich solution that gives plants all the food they need for healthy growth.
What are the different types of hydroponic systems?
There are literally hundreds of different variations of hydroponic systems but they all generally adhere to one of eight principal techniques. Each hydroponic system works in a slightly different way and it’s important to identify and understand these differences so that you can choose the best system for your needs.
Let’s take a look at each of the eight hydroponic types, starting with the Wick method.
1. Wick Hydroponics
A wick-based hydroponic system takes advantage of something called ‘capillary action’, the process by which water is drawn through a narrow space without the assistance of, or in opposition to, any external forces like gravity. This means that wick hydroponics is one of the few hydroponic systems that does not require any sort of pump or any energy to run.
The key to the whole system, as you may have guessed, is the wicks. The wicks, which are usually made of an absorbent fibre, connecting the base of each plant to the nutrient-rich solution below. Through the process of capillary action, the solution is drawn (wicked) up the wick and directed to the growing medium around the roots.
This growing medium, made from a porous material like clay stones, rock wool or perlite, in turn, absorbs the water from each wick and becomes gradually saturated. It is this saturation that allows the roots of each plant to access water and nutrients.
This is the exact same process that is used in most Smart Gardens, like my Click & Grow 3 or the larger Click & Grow 9.
Which plants grow best in wick hydroponics?
As a general rule, plants which don’t require much water to grow are best for wick hydroponics. Things like herbs and leafy greens such as lettuce will likely flourish. Plants with deeper root systems tend not to do so well.
What are the advantages and disadvantages of wick hydroponics?
| Advantages | Disadvantages |
|---|---|
| Requires no electricity to run | Only suitable for plants which require little water |
| Doesn’t require continued manual watering | Not as efficient at nutrient delivery as other systems |
| Doesn’t cost anything to run | Wicks can become clogged over time |
| Uses water very slowly |
2. Ebb and Flow (aka Flood and Drain)
Ebb and Flow hydroponics (also called Flood and Drain) is another popular form of hydroponics that is designed to regularly wash the roots of plants in a nutrient-rich solution. Within an Ebb and Flow hydroponic system, plants are positioned within large grow beds above a reservoir and supported by a loose, porous growing medium like perlite or grow stones. At regular intervals, a water pump forces the nutrient solution up into the grow bed where it then washes over the roots.
The grow bed is usually positioned at a slight angle so that water is allowed to flood the entire grow bed before draining back into the reservoir through a small plug hole in the opposite end of the grow bed. To regulate the flow of nutrients, an automatic pump timer can be added to switch power to the pump on and off at pre-determined intervals.
Which plants grow best in Ebb and Flow hydroponics?
Ebb and Flow hydroponics is great for most small-medium size plants, including some root vegetables (which require a much deeper grow bed). Larger plants aren’t recommended. Popular plant types include lettuce, kale and other leafy greens.
What are the advantages and disadvantages of Ebb and Flow hydroponics?
| Advantages | Disadvantages |
|---|---|
| Allows plants to ‘dry out’ at intervals which helps prevent root rot and disease | It’s possible to over-saturate plants if floods aren’t timed properly |
| Doesn’t require continued manual watering | Not as efficient at nutrient delivery as other systems |
| Doesn’t cost anything to run | Wicks can become clogged over time |
| Very efficient use of water | Not durable for larger plants |
| Can be scaled to house a large number of plants | Requires regular monitoring |
3. Drip Hydroponics
Drip hydroponics follows a very similar technique to that employed by Ebb and Flow hydroponics but with a couple of key differences. While plants are still placed in a grow bed and positioned above a reservoir, they are not held within a grow medium like perlite or grow stones that in Ebb and Flow systems fill the grow bed. Instead, plants are held in a growing medium like rock wool and suspended in small, individual net pots and fastened to a lid which is positioned over the grow bed.
Drip emitters, connected to the water pump by a long tube, are then placed at the base of each plant. When the pump is switched on, these emitters precisely drip water directly onto the roots of each plant. Excess water is allowed to flood away from the roots and drain back into the reservoir to be recycled. The drip rate can be altered or set in cycles to manage the level of water and nutrients received by the plants.
Which plants grow best in Drip System hydroponics?
Like Ebb and Flow, Drip hydroponics is a great option for growing a diverse range of small to medium-sized plants. However, because plants are usually suspended within individual net pots, root vegetables can be tricky and I wouldn’t recommend it. Leafy greens like lettuce, rocket, and herbs grow particularly well.
What are the advantages and disadvantages of Drip System hydroponics?
| Advantages | Disadvantages |
|---|---|
| Offers decent control over feedings | Requires quite a lot of monitoring (i.e. for water PH) |
| Relatively inexpensive to run | Can be a little slow for plants that require more water |
| Can be scaled to grow multiple plants | |
| Very efficient use of water | Not durable for larger plants |
| Can be scaled to house a large number of plants |
4. Nutrient Film Technique (NFT)
Nutrient Film Technique (commonly referred to as ‘NFT’) is a popular form of hydroponics that is designed to supply a thin film of nutrients directly to the plant’s roots. Like and Drip system, plants are suspended above the grow bed in net pots. Water is pumped into the grow bed from a reservoir below and gently washes over the ends of the plant’s roots (only a small amount of water is pumped to create a thin film).
The grow bed is angled slightly to allow water to drain at the other end before being captured by the reservoir and recycled. To keep the water oxygenated, an air pump is often used to pump air through a set of air stones that can be placed at the base of the reservoir. Air stones help to circulate air around the tank by producing tiny bubbles filled with oxygen.
Which plants grow best in NFT hydroponics?
NFT is best for growing plants with small, shallow root systems that are not prone to overgrowth and therefore risk blocking the channels in the grow bed. Leafy greens like lettuce are great for NFT. Larger plants and root vegetables are not suitable.
What are the advantages and disadvantages of NFT hydroponics?
| Advantages | Disadvantages |
|---|---|
| The thin ‘film’ of water ensures plant roots are saturated or suffocated | More expensive to set up and run |
| Minimal/no growing medium is needed for plants | Reliant on two different pumps (more to go wrong) |
| A very efficient system with minimal waste | Roots can overgrow and intertwine within the channel |
5. Aeroponics
Aeroponics is a niche form of hydroponics that is designed to suspend plants in the air and spray them with a fine, nutrient-rich mist at frequent intervals. The plants are held directly over the reservoir, which is filled with water and nutrients. A pump, which is connected to a misting system, sprays fine water droplets directly over the roots of each plant via several mist novels. Excess water drops directly back into the reservoir to be recycled.
Misting the plants in this way ensures that roots are key and well-oxygenated and prevents over-saturation or full submersion which can lead to root rot and other issues. This mist can be set to cycles or run continuously depending on the specific needs of the plants being grown.
What are the best plants to grow with aeroponics?
It’s possible to grow almost any plant, even larger ones, with aeroponics, provided you have the right equipment and set-up. It’s critical that the misting system is able to spray the entire root system and continue to do so as it grows. Larger plants which are not properly serviced by the system may struggle and roots may become dry or diseased.
What are the advantages and disadvantages of aeroponics?
| Advantages | Disadvantages |
|---|---|
| Roots are oxygenated | Quite difficult to build |
| Water is used very efficiently | More expensive to set up |
| Prevents over-saturation and limits disease | More complex parts can fail |
6. Aeroponic/hydroponic Tower
An aeroponic tower is another form of hydroponic growing where plants grow around a vertical tower. This form of vertical gardening is especially popular with commercial vertical farms but is becoming increasingly accessible to amateur growers thanks to consumer companies like Tower Garden.
These aeroponic tower gardens are designed to suspend plants in net pots all the way up the central column. A large amount of nutrient-rich solution can be held in the reservoir at the base of the tower. A water pump then pumps water from this reservoir through a rube all the way to the top of the tower.
Here, the water exists vis a 360-degree spray nozzle that distributes water evenly before gravity pulls it back through the tower and into the reservoir. As the water falls back to the reservoir, it washes over the roots of the suspended plants, oxygenating them and providing them with nutrients.
What kinds of plants can you grow in an aeroponic tower?
Like other aeroponic systems, an aeroponic tower is a great system for growing many different types of plants – both big and small. As with most vertical and hydroponic gardening, I find growing leafy greens and herbs always works best (I’ve had great success with basil, baby gem lettuce, kale and parsley). However, tower gardens are capable of supporting larger fruiting plants like tomatoes, cucumbers and even zucchini.
What are the advantages and disadvantages of NFT hydroponics?
| Advantages | Disadvantages |
|---|---|
| Roots are oxygenated | Quite difficult to build |
| Prevents over-saturation and limits disease | More expensive to set up |
| Towers are robust and can support larger plants | Can be quite larger and bulky |
7. Deep Water Culture (DWC)
Deep water culture is a method of hydroponic growing that suspends the roots of plants directly into nutrient-rich water. The plants and roots are suspended above a reservoir in net pots, ensuring that the pots and roots are held continuously below the water line, giving them a constant supply of water and nutrients.
No water pump is needed, but to maintain oxygen and prevent roots from ‘drowning’ an air pump and air stones are required. Air is pumped through the air stones, which created small bubbles of oxygen that are absorbed by the water and the plant’s roots.
What kinds of plants can you grow via Deep Water Culture?
Deep Water Culture works especially well for plants with larger root systems. It’s important to ensure there is enough depth in the reservoir to accommodate this. The constant supply of nutrient-rich water means the DWC is often used for growing almost any plant. However, large top-heavy plants (like tomatoes) may not be well suited. Plants like lettuce and other lightweight leafy greens work best.
What are the advantages and disadvantages of Deep Water Culture?
| Advantages | Disadvantages |
|---|---|
| Low cost and relatively cheap to maintain | Not well suited for larger, top-heavy plants |
| Can store large amounts of water which is efficiently cycled | Submerged roots are at high risk of disease |
| Requires minimal effort to manage | Roots can ‘drown’ if not properly oxygenated |
8. Kratky Method
Finally, the Kratky Method. This is arguably one of the most passive and simple hydroponic systems. Plants are simply suspended in net posts above a small reservoir containing a nutrient-rich solution. Like DWC, the roots spend nearly all their time submerged within the reservoir. Except, with Kratky, no air pump is used to supply the roots with oxygen. As the roots absorb water, the level of the reservoir drops.
A popular method of growing plants in this way is to use a mason jar.
What kinds of plants can you grow via Kratky hydroponics?
Owing to its relatively small scale, the Kratky method works best with lightweight plants with deep root systems that can anchor them to the reservoir and prevent tipping. Leafy greens and herbs work best.
What are the advantages and disadvantages of the Kratky method?
| Advantages | Disadvantages |
|---|---|
| Very simple design | You can only grow one plant per system |
| Can be run possibly with minimal effort | Roots are susceptible to rot and drowning |
| Can be built into almost any container, including mason jars. | Only suitable for small plants |
In conclusion
In this article, we’ve explored eight hydroponic techniques each with different approaches to growing plants and with their own advantages and disadvantages. When choosing which hydroponic system is right for you, consider first your budget and experience. Complex, expensive systems like Nutrient Film Technique may not be a good place to start your hydroponic journey. Consider next the types of plants you want to grow, and how you want to grow them. There is something out there for everyone.
Personally, I grow most of many plants in my aeroponic tower garden which, while a little expensive to purchase up front, gives me the freedom to grow more or less anything while maintaining a very small footprint (one of the many benefits of vertical gardening). I also employ wick hydroponics in my Click & Grow Smart Garden, which is great for growing leafy greens and herbs.
