Vertical farming in short

Vertical farming is a specialized application of hydroponic farming in which plants are grown without any soil using vertical layers. Instead of using just a single horizontal plane of production, like what is typical to a conventional farm or a hydroponic greenhouse, vertical farms utilize both the horizontal and vertical planes. This is particularly useful considering the growing pressure to increase crop yields per unit area of land. So instead of maximizing the yield per square meter as is done in conventional farming or in hydroponic greenhouses, vertical farming strives to maximize the production per available cubic meter. As of today, vertical farming is particularly suitable for the production of small horticultural crops such as leafy greens and vegetables, while not so for taller crops such as different grains.

While the definition for vertical farming is commonly understood to mean vertical plane production, it’s good to understand that vertical farming is actually just a top-level term for a wide range of farming techniques. Vertical farming can be divided into a range of different growth systems with different technologies and meant for different applications. Regardless, vertical farming is often associated with urban indoor farming, an application that we at Arctic Farming are also researching. Next, we will define the most common categories of vertical farming systems.

Categories and subcategories of vertical farming

In our previous blog we spoke about the different types of hydroponic farming systems and techniques, and we learned that hydroponics can be done using a liquid culture system or as an aggregate culture system, and using a range of growing techniques including aeroponics, Nutrient Film Technique (NFT), Drip Systems and so on. All these systems and techniques are also applicable for vertical farming. However, in addition to these applications, vertical farming can be divided into two broad categories – the stacked horizontal systems, and the vertical surface systems. While researchers and practitioners have not yet come to agreement on exact definitions for these categories, nor to each individual subcategory, we argue that while not perfect, Beacham, Vickers and Monaghan (2019) offer the best descriptions for each. These descriptions are represented in the figure below.

Stacked horizontal systems

Stacked horizontal systems come in a variety of configurations (represented in the figure by a, b, c, d). What is common to all these systems is that stacked systems comprise multiple layers or tiers of growing platforms. Stacked systems can be built from fixed (b) or rotating (a) platforms with the growth environment being open (a, b) or isolated (c). In open systems, all plants are exposed to the same environmental variables, while in an isolated system, each tier has its own environmental control system to help with temperature, humidity and pest control. Using these kinds of self-contained tiers also allows the lights to be optimized for each individual type of plant. These individual controls allow a wider range of plants to be grown in the same tower because each tier can be tailored to suit a separate plant. In addition to the previous systems, stacked systems can also utilize a balcony design (d). In this system, the plants grow on physical outcrops that extend out from a wall.

Vertical surface systems

Vertical surface systems can be divided into three rough subcategories, two of which were described by Beacham et al. (2019). These subcategories are the green walls (e), cylindrical growth units (f) and vertical tower units. Green wall farming is a promising type of hydroponics in which plants are grown in vertical or inclined growing platforms. While Beacham et al. (2019) describe the use of such wall mostly on building facades, this is only one narrow application of the green wall design. In fact, green wall designs have shown some significant promises particularly in urban indoor farming and it is also the design that Arctic Farming modules are based on.

In addition to the green walls, vertical surface systems can be based on a cylindrical growth unit in which plants are grown one above another around the surface of an upright cylindrical growth unit. While these systems are achieve a high production level per unit of land used, the design is not suitable for all applications due to the need to have access to 360 degrees around the cylinder for harvesting.

The last vertical surface system we need to discuss is based on a vertical tower design. This design, which one could argue was behind most of the current vertical surface designs, was pioneered by Dr. Nate Storey from Plenty (formerly at Bright Agrotech). Dr. Storey designed the revolutionary ZipGrow growing tower which was later acquired by Plenty, a US based AgriTech company backed by significant investors like Bezos Expeditions and Softbank Investment Advisors.

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What is the best vertical farming design?

With all the above-mentioned categories and subcategories of vertical farming, one might easily get confused about the differences and benefits of each design. And alas, while each design has its own pros and cons, we would argue that a combination of two of these designs – the isolated vertical system (c) and the green wall system (e) is showing a lot of promise especially in urban indoor farming contexts.

By combining the isolated vertical design with a green wall system, we have been able to develop an AI based farming module that is fully automated and functions as an independent ecosystem with its own automation and controls. These controls are supported by machine learning and machine vision systems that monitor every aspect of the plants’ growth. This allows us to optimize the growth of each plant regardless of the surrounding environment. This kind of an isolated design is an optimal choice for a retail, wholesale or restaurant environment where the surrounding environment is not optimal for plant growth. However, since an isolated system can be implemented in several configurations, isolating a system is not by itself what makes a vertical farming module more efficient that other solutions. Instead, it is the green wall-based design that makes for the most efficient configuration. This is due to the two major differences between vertical plane and horizontal plane production – production per units of area used, and the logistics of managing a vertical farming system.

We will discuss the differences between vertical plane production and horizontal plane production in more detail in a future post but for now, if you want to learn more about the benefits of a green wall-based design, please contact us using the form below.

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With the increasing interest in the vertical farming market, there is a need for new innovative solutions. If you are interested in hearing more about these technologies and how we approach vertical farming, please contact us using the contact form below.

Sources:

Beacham, A. M., Vickers L. H., & Monaghan, J. M. (2019) Vertical farming: a summary of approaches to growing skywards. The Journal of Horticultural Science and Biotechnology, 94(3), pp. 277-283.

What is vertical farming?