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Selecting the ideal hydroponics system can be a daunting task with numerous variables at play. At the heart of these considerations lies the quest for efficiency, a goal every hydroponic enthusiast aspires to. In my view, hydroponic towers represent a pinnacle in this efficiency race.
But do they truly live up to the hype?
Hydroponic towers stand out as one of the most efficient hydroponics systems, excelling in water conservation, growing capacity, energy efficiency, and reduced maintenance costs, making them a popular choice for both hobbyists and commercial growers alike.
In this article, we’ll dissect the efficiency of hydroponic towers, examining water and energy consumption, plant growth rates, operational costs, and more, providing a comprehensive insight into their place within the broader hydroponic landscape.
Understanding how a vertical hydroponic system works
Before we assess the efficiency of hydroponic towers let’s first quickly examine what they are and precisely how they work.
A vertical hydroponic tower is a fantastic and efficient way to grow plants without the need for soil, like in traditional growing methods.
Top tip: Check out my article on hydroponic towers: what they are and how they work.
The system is typically constructed using a tall, cylindrical structure complete with rows of evenly spaced holes in which to place plants, usually supported in plastic net cups.
Here’s a simple diagram to help visualize what I mean:
The hydroponic tower system works by pumping a nutrient-rich solution from the reservoir at the bottom to the top, where it exists from a perforated nozzle before dripping through the tower and back down to the reservoir.
As it does so, the nutrient solution brushes over the plant’s roots which are dangling inside, and provides them with both water and sustenance.
Active vs. passive systems
A hydroponic tower is an ‘active’ hydroponic system. This means that it requires some energy to work. While this makes it less efficient than a ‘passive’ system like Kratky or Wick Hydroponics (which requires no energy), a hydroponic tower is still one of the most efficient hydroponics systems out there.
What makes a hydroponic tower system active? Well, it’s the water pump. The pump is required to pump the nutrient solution through the system.
Analysing the efficiency of a vertical hydroponic tower
Let’s dive into some of the specifics.
To effectively analyze the efficiency of a vertical hydroponic tower system there are several criteria we need to test from the system’s footprint and size to the amount of energy that it uses to function.
It’s also important to determine the financial efficiency of the system as this is often one of the most important determining factors for those wishing to buy a hydroponic tower system for themselves.
For the purposes of this assessment, we will analyze hobbyist systems only, not commercial systems.
1. Space efficiency
A primary benefit of hydroponic towers is the minimal space they occupy due to their compact footprint. In general terms, a hydroponic tower system can grow more plants per square foot than almost any other type of hydroponics system.
Real-world example – calculating the space efficiency of my own towers.
I own two hydroponic towers. My largest tower (1.5m) can host a total of 35 plants, while my smaller tower (1m) can host a total of 18.
That gives me a total growing capacity of 53 different plants.
Let’s calculate the surface area of the base of each tower (which is essentially the footprint it takes up on the ground). We can calculate this by using the formula: Base Surface Area=width×length.
|Base Surface Area (ft²)
|1m Hydroponic Tower
|1.5m Hydroponic Tower
To make it a little easier to digest, I’ve converted the base surface area into square feet using this formula: 1 ft2=929.0304 cm2.
So what do these numbers actually mean?
Well, it means that I am able to grow 53 plants in a total surface area of 2.7 ft2. That’s 1 plant for every 0.05 ft2 of space.
That’s very space-efficient! This is one of the key reasons commercial vertical farms use vertical hydroponic towers.
2. Water efficiency
In terms of water usage, hydroponics stands out as a highly efficient method for food cultivation.
A hydroponic tower, like most hydroponic systems, is a closed-loop system. This means water is recirculated within the system, dramatically reducing waste. As plants absorb only the water they need, the excess can be captured and reused.
As a result, it’s not unusual for hydroponic towers to save up to 98% of the water used compared with traditional soil-based growing.
For hobbyist growers and commercial farmers alike, this presents a significant saving, both in terms of water use and costs.
3. Energy efficiency
The appeal of hydroponic tower systems isn’t solely due to their ability to conserve water efficiently. They’re also among the most energy-efficient types of hydroponic systems.
Hydroponic towers, especially those used indoors or in controlled environments, rely on artificial lighting to provide plants with the necessary light spectrum for growth. While this might sound energy-intensive, technological advancements have led to the development of highly efficient LED grow lights.
A typical LED light array, made from 3 x 60cm LED grow lights, could use only around 36 watts per hour to provide sufficient light to a hydroponic tower.
Water and nutrient solutions are typically circulated using pumps in hydroponic setups. Modern pumps are designed to be energy efficient, and because they operate in closed-loop systems, they often need to run for shorter durations than one might expect.
An average water pump uses only around 50 watts of energy per hour.
4. Plant growth efficiency
Hydroponic towers excel in cultivating plants, particularly lettuces and various leafy greens, though other systems also showcase comparable effectiveness.
Top tip: I’ve written an article about the 10 best plants to grow in a hydroponic tower if you’re interested to learn more.
Hydroponic tower systems provide growers with a range of benefits, enhancing the cultivation of various plant types, including:
- Direct nutrient delivery: In hydroponic tower systems, plants receive a direct and consistent supply of water and nutrients. This means they don’t expend energy searching for nutrients in the soil, resulting in faster growth rates.
- No soil-borne diseases: The absence of soil eliminates the risk of many soil-borne diseases, reducing plant stress and promoting healthier, faster growth.
- Controlled environment: Many hydroponic tower systems can be placed indoors or within greenhouses, allowing for year-round growing and shielding plants from adverse weather conditions that could hamper growth.
- Root system development: With ample access to oxygen and no soil to navigate, plants can develop more compact, efficient root systems, focusing their energy on upward growth and fruit/flower production.
However, to ensure effective plant growth you must ensure that you properly maintain your hydroponic tower system and make sure to keep it clean.
Additional reading: How to maintain your hydroponic tower.
Additional reading: How to keep your hydroponic tower system clean.
5. Cost to run
Understanding the operational costs of any cultivation method is essential for both hobbyists and professionals. For hydroponic tower systems, the ongoing energy costs are a significant factor to consider. Let’s examine the costs associated with running a hydroponic tower system that consumes 80 watts per hour and operates for 16 hours daily.
Energy Consumption: To gauge the daily energy consumption, we’ll convert the system’s power rating to kilowatt-hours (kWh) since it’s the standard billing unit for electricity.
- System power rating: 80 watts = 0.08 kilowatts (kW) made up of a water pump and lights
- Operating time: If the system runs for 16 hours daily, it would consume: 0.08 kW×16 hours =1.28 kWh 0.08 kW×16 hours=1.28 kWh
Cost Calculation: Using the given rate of 20 cents per kWh, the daily cost to operate the system is: 1.28 \ kWh \times $0.20 = $0.256 Thus, the system would cost approximately $0.256 (or 25.6 cents) to run for 16 hours.
Monthly and Annual Perspective: To further understand the cost, it helps to look at monthly and yearly expenditures:
- Monthly: $0.256 x 30 = $7.68 (assuming 30 days in a month)
- Annually: $0.256 x 365 = $93.44
In this scenario with an 80-watt system running 16 hours daily, the approximate yearly electricity cost would be just $93.44 annually at the provided rate, which is pretty cost-effective.
High initial cost
Hydroponic towers are some of the highest-cost systems to buy or build, with ready-to-go systems from manufacturers like Tower Garden or Nutraponics costing anywhere from $100-$1000.
Which are the most efficient hydroponic methods?
The term “most efficient” can vary based on the specific criteria under consideration (e.g., water usage, energy consumption, yield per square foot, etc.).
However, if considering cost to run and the use of energy and water, then, passive systems (which do not use any energy to function) stand out for their cost-efficiency and simplicity.
Both Wick and Kratky methods require virtually no energy, making them ideal for growers keen on minimizing operational costs.
They come with some disadvantages, but for growers looking to create a zero-cost hydroponics system, they’re a great place to start.
Potential limitations with vertical hydroponic towers
Hydroponic towers, while efficient systems with which to grow an abundant amount of leafy greens and other plants, do come with some drawbacks when compared with other systems.
More difficult to light effectively
Due to their tall, cylindrical shape, hydroponic towers can prove more difficult to light compared with other horizontal systems. Achieving an even light distribution can also be a challenge.
In some instances, growers may be required to rotate their hydroponic tower to ensure all the plants receive an even amount of light.
I’ve written a whole article about this: Do you need to rotate your hydroponic tower?
The initial cost of the system can be quite high
As I mentioned above, hydroponic tower systems are often in the more costly range to either construct or purchase from a retailer.
This might price out some hobbyist growers who are looking for a more affordable solution for growing plants at home.
You can only grow certain plant types
While hydroponic towers can accommodate a wide range of plants, certain plants are less suited for this system due to their growth habits, size, or specific growth requirements.
Growing root vegetables in a vertical system can be difficult, for example.
Here are some plants that might not thrive in hydroponic towers:
- Large Fruit Trees: Such as apple, orange, or peach trees. These trees need space for their extensive root systems and are too large for typical tower systems.
- Root Vegetables: Such as carrots, potatoes, and beets. These plants need depth to develop their edible roots, and hydroponic towers may not offer sufficient space.
- Tubers: Similar to root vegetables, plants like yams or sweet potatoes require more depth than a tower system usually provides.
- Corn: Its tall stalks and root structure are not ideal for the constraints of a vertical system.
- Vining Plants: While some vining plants can be trained to grow vertically, others, like pumpkins or watermelons, can be challenging due to the weight and size of the fruit.
It’s worth noting that while the above plants might not be ideal for hydroponic towers, many of them can still be grown hydroponically using other systems tailored to their specific needs.
Top tip: Check out my article on the Top 10 Best Plants to Grow in a Vertical Hydroponic Tower.
Advantages of hydroponic towers
There are many advantages to a hydroponic tower over other system types.
1. Space efficient
As previously mentioned in this article, hydroponic towers stand out as one of the most space-efficient systems for both hobbyists and commercial growers.
Their remarkable capacity to cultivate a diverse range of plants in a limited area makes them the preferred system for many hydroponic farms, commonly referred to as ‘vertical farms’.
2. Easy to move indoors or out
Because hydroponic towers are closed systems, they’re easier to move around than other types of hydroponics systems.
This means you can move them inside during the winter months, or outside when the weather is good in spring and summer.
3. Less bending over
Vertical gardening is a great way to make growing plants at home a more ergonomic experience. By elevating plants to eye level, you can almost eliminate the need for constant bending, making garden care safer and putting less strain on your joints.
Hydroponic towers offer notable space and resource efficiencies and are among the most efficient systems on the market. However, they come with distinct challenges, from plant type restrictions to setup and maintenance concerns.
While their compact design appeals to many, a comprehensive understanding of their benefits and limitations is essential for optimal results and research is key to making an informed decision.