When Plenty was founded in 2014 by CEO Matt Barnard and chief science officer Nate Storey, it was based on a core idea: Field agriculture was too unpredictable, and controlled environment, high-tech growing was a better way to supply quality food to a world that will need more of it in the years to come.

“There will be an increasing need, both for food in the world, as well as variability around the food supply,” Storey says. “We scaled up over the years. And as we’ve done that, the vision has of course not necessarily changed, but deepened, I would say, to include the idea that people don’t just need access to food, period, they need access to really good food.”

Plenty’s first farm — Storey calls it a container farm — was on the campus of a large technology company in San Francisco, and over time has grown to 100,000 square foot facilities. The business also evolved from its early days, when Barnard was using much of his own money to fund it and Storey splitting his time between his own startup — Bright Agrotech, based out of his previous home of Laramie, Wyoming — and Plenty, to receiving multimillion-dollar investments from investment groups that include Amazon founder Jeff Bezos and Masayoshi Son, the richest person in Japan with an estimated net worth of $23 billon, according to Forbes.

It was at this California-based tech company the heart of America’s currently booming tech industry, that Plenty found what worked and what didn’t in its system.

“[Starting there] basically give us time to learn, to understand the problems really clearly, and understand how indoor production can possibly solve the [problems] that we were identifying in the field,” Storey says.

How the system works

Plenty, which is currently based in San Francisco, is unlike most other vertical or container farms that grow plants on horizontally stacked shelves. Instead, Plenty uses tall poles to house the plants, which then grow out horizontally. Each pole is a few inches away from the next one, allowing crops to grow densely to the point where they essentially form a wall. The setup also allows excess heat from the lights to rise into the vented ceiling and excess water to drip down to the bottom of the plant towers and into a recyclable indoor stream, with space in front of the walls for workers to check on the plants’ health during the growing process. All of the water is then filtered and recycled back into the farm. As for harvesting, robots can handle at least part of it, but Plenty sees expertly trained human labor as a key part of its recipe.

Plenty, according to Storey, has benefited, and should continue to benefit, from the rapid evolution of growing technology.

“All of these things are dropping, precipitously, and it opens the doors for us to start leveraging that information, and those technologies, in ways that both drive costs out of our model, and make it feasible,” Storey says. “It’s true. A lot of folks who looked at this five, six years ago and said that that is not possible, they were right. It wasn’t possible that day. [It] wasn’t possible at that time, because the technology hadn’t evolved. No one — well, a few people predicted it — but very few people predicted the ways in which the economics of this business would change. And how fast it would change.”

What’s next?

The decreasing cost of technology also helps Plenty work towards another one of its goals: making its products more affordable.

“If our goal is just to produce a premium product we would be a much smaller business,” Storey says. “We would have to be content with being a smaller business. Our goal is, of course, to build a business that is global.”

A story published in Bloomberg indicated that Plenty has global ambitions and, with Son’s backing, has the financial means to expand. According to Bloomberg, Barnard has met with 15 governments on four different continents.

“It’s never going to replace the field by any means, but it’s going to become a really important part of our food production system,” Storey says. “[Our model] is stable, and it allows us to produce some of these high value horticultural products, closer and closer to people. And we just think that’s an important part of the experience, in a lot of different ways. In the next five years, 10 years, 15 years, I think we’re going to see our farms spring up all over the world. I think that people are going to be surprised at the diversity of crops that end up coming out of our farms.”

The diversity of crops is key to Plenty’s plans, which is why the company has a research and development division dedicated to developing genetics for its system because some seeds bred for field are not fit for any indoor growing system, much less one as advanced as Plenty’s. As that part of the business continues to develop, it allows the business to expand.

“We’re working both angles,” Storey says. “It’s important to us that we’re not just finding the appropriate environment for the crop. We want to grow, but we’re finding the appropriate crop and the appropriate environment. We’re kind of having this melding of both sides of the equation, and getting to the best possible place, as fast as possible.”

This article series is from the Resource Management in Commercial Greenhouse Production Multistate Research Project.

Indoor vertical farming systems or plant factories use controlled environment agriculture (CEA) technologies to grow high-value horticultural crops year-round in pre-existing urban warehouses or shipping containers. The internal building of warehouses is most often converted into a growing environment with the goal of achieving higher biomass production compared to outdoor or greenhouse production. The essential components of a vertical farm include multi-layer production shelves, hydroponic, aeroponic, or aquaponic growing systems and sole-source electrical lighting consisting primarily of high-intensity light-emitting diodes (LEDs) (Figs. 1A and B) or fluorescent lamps. However, detailed engineering design fundamentals for heating, ventilation, and air conditioning (HVAC) systems, uniformity of the environment, optimal delivery of carbon dioxide (CO₂), shelf spacing, smart lighting and shelf designs, and interaction of crops and surrounding climate in terms of heat and mass-transfer processes are often overlooked in such retrofits. Optimizing the use of resources such as energy, water, nutrients and CO2 is essential for the long-term viability of vertical farm systems, where energy intensive lighting and HVAC systems can account for close to one third of the overall operational costs. The operational costs and resource use efficiency (defined as the ratio of resource fixed by the produce to resource used by the plant; Kozai, 2013) of multi-tier-based vertical farm systems can be improved by appropriate production system design modifications for key technologies and control strategies while considering the crop-specific minimum environmental requirements such as light intensity and quality, air temperature, velocity and flow pattern, CO₂ and uniformity of these variables.

Many millennial vertical farmers are data-driven and rely on recent technology developments in sensors, environmental monitoring and control, and information and communication technologies. Integrated monitoring and control of the crop and production system and analysis on average account for about 9 percent of a farm workforce’s weekly labor hours (Agrilyst, 2017). It is expected that these technologies will further advance with integration of the diverse set of analytics platforms made available for growers and system operators empowering them to improve production quality and overall resource use efficiency. The technologies that vertical farming operations are most excited about include automation, HVAC, LED lighting systems, smart sensors and data analytics.

Challenges in vertical farming

Several economic challenges make vertical farming a difficult sector to enter and be profitable including both high start-up costs (particularly lighting, vertical growing systems, and sufficient HVAC capacity) and high operating costs (especially energy and labor). In greenhouses, labor is typically the largest production cost followed by energy. In vertical farms, energy costs may be equal to or greater than labor. In a recent survey of CEA operations, 27 percent of vertical farms reported being profitable as compared to 67 percent of greenhouses (Agrilyst, 2017).

In 2016, an energy use simulation was conducted for lettuce production in greenhouses and vertical farms in diverse climates across the U.S. Per unit of lettuce, vertical farms in Minneapolis would require 1.4 to 2.4 times more energy than greenhouse counterparts; while in an arid climate like Phoenix, a vertical farm would require five to 10 times more energy than greenhouses (Harbick and Albright, 2016). Energy use was evenly split between lighting and HVAC systems. Another simulation-based study (Graamans et al., 2018) compared greenhouses vs. vertical farms in the Netherlands, United Arab Emirates, and Sweden in terms of resource use efficiency per unit biomass of lettuce: In all cases, purchased energy (heating plus electricity) used by greenhouses was less than plant factories. Climate made a large difference in the extent of energy savings. In a moderate climate like the Netherlands, greenhouse energy was three times less than the plant factory, while in an extreme northern climate like Sweden, greenhouses used only 15 percent less energy than plant factories. However, beyond energy, it was noted that vertical farm-based production could achieve higher productivity for all other resources (water, CO2, and land area). Currently, energy costs average $8 per square foot production space and represented 25 percent of annual production costs in large vertical farms (Agrilyst, 2017). Therefore, there is further need for research on analysis of resource use efficiencies and to develop resource-conserving environmental control strategies (Fig. 2).

Automation in vertical farming

While indoor production may lend itself to increased automation (vs. field production), the nature of vertical farming (multi-layered production) appears to make it difficult to automate. Processes that in 2-D greenhouses (moving plants to the production space, respacing, sorting, and harvesting) are more time-consuming and labor-intensive in 3-D. For example, accessing crops for maintenance, monitoring, and pulling for harvesting typically requires added labor time through use of ladders or scissors lift in vertical farming (Fig. 3). Thus, automation and robotics systems need to be integrated for such operations.

Nutrient management in vertical farms

Indoor vertical farming operations take advantage of technology and automation to improve production efficiencies. This includes optimization of the root-zone (in terms of pH, fertilizer nutrients and dissolved oxygen) to produce high-quality crops and reduce nutrient waste. However, managing nutrients in vertical farming does not have to be high-tech or complicated. In addition, common nutrient management techniques used in greenhouse hydroponic and container crop production also apply to vertical farming.

Measuring electrical conductivity (EC) and pH in the rootzone are common methods for monitoring crop fertility. EC refers to the concentration of total nutrients surrounding roots, where greater EC values indicate a greater nutrient supply. pH refers to acidity or basicity in the root zone (where pH 7 is neutral), which influences the solubility and availability of nutrients for uptake. For most crops, nutrients are adequately available at pH 5.6 to 6.4. Multiple factors interact and can influence nutrients and pH during vertical farming production. For strategies on managing these factors, check out our previous Produce Grower article, “Edible crop species differ in their pH effect in hydroponics,” at bit.ly/2CNsGUk

In addition to measuring root-zone pH and nutrient levels, growers should periodically conduct detailed nutrient analyses on both the applied nutrient solution and plant tissue using a commercial lab. This helps growers check their own in-house pH and EC measurements, and verify that they are supplying individual nutrients in the correct amounts. Tissue nutrient analyses provide information on the amount of nutrients the plants are taking up, which helps growers adjust their fertilizer program for optimal plant growth and diagnose nutritional problems. Visual inspection of plants to diagnosis nutrient and other disorders remains important in plant factories but can be difficult under sole-source LED lighting. For example, under narrow waveband red and blue light, plant surfaces appear pink or purple. Some lights have a human vision feature to turn OFF red/blue light and turn ON white (broad-spectrum) light to inspect plants, or operators use special glasses with green lenses to see plants with natural colors. Computer vision systems can help enhancing plant inspection for growth, health monitoring and environmental control purposes and as an integral part of needed automation and robotics applications.

Future prospects

Vertical farming can meet consumer demand for high-quality, nutritious, chemical-free, and locally grown horticultural crops. Due to high production costs, there should be additional benefits delivered by sole-source lighting and CO₂ enrichment (such as phytochemical, nutrient or color enhancement). Research and development to improve labor and energy-use efficiency as well as increased uniformity of the growing environment will be important to address industry viability/profitability. Further, there is an increasing demand by the vertical farm industry for an educated/experienced workforce who understand both the biology and engineering of controlled environment crop production systems. Because the industry is young, the workforce has largely come from related industries without prior experience specifically in indoor climates. Therefore, it’s critical to maintain and further grow controlled environment agriculture-based research, educational, and extension/outreach programs offered by higher education institutions to meet the industry’s demands.

References

Agrilyst. 2017. State of indoor farming. https://www.agrilyst.com/stateofindoorfarming2017

Graamans, L., E. Baeza, A. van den Dobbelsteen, I. Tsafaras, C. Stanghellini. 2018. Plant factories versus greenhouses: Comparison of resource use efficiency. Agricultural Systems, 160: 31-43.

Harbick, K. and Albright, L.D. 2016. Comparison of energy consumption: greenhouses and plant factories. Acta Hortic. 1134, 285-292.

Kozai, T. 2013. Resource use efficiency of closed plant production system with artificial light: Concept, estimation and application to plant factory. Proceedings of the Japan Academy, Series B, Physical and Biological sciences, 89: 447-461.

Ying, Z. and M. Kacira. 2017. Analysis of environmental uniformity in a plant factory using CFD analysis. Presented at GreenSys 2017-International Symposium on New Technologies for Environment Control, Energy-Saving and Crop Production in Greenhouse and Plant Factory, August 20-24, Beijing, China.

Acknowledgements

Financial support was received from the USDA National Institute of Food and Agriculture, Multistate Research Project NE-1335: Resource Management in Commercial Greenhouse Production. Murat is a professor at the University of Arizona (mkacira@email.arizona.edu), Ryan is an extension professor/specialist at the University of New Hampshire (Ryan.Dickson@unh.edu), Neil is an associate professor and extension specialist at Cornell University (neil.mattson@cornell.edu) and Roberto is an assistant professor and floriculture/controlled environment specialist at Michigan State University (rglopez@msu.edu).

Nick Chaney, the head grower at BrightFarms’ Chicagoland greenhouse, helped develop the hydroponic grower’s newest lettuce variety: Sunny Crunch. Chaney says that BrightFarms knew Sunny Crunch would be a success when it drew rave reviews from people who tried it during a greenhouse visit.

“Everyone who pulled one of those leaves out of the system and tried it, you could see their face just lighting up,” Chaney says. “When we started seeing that reaction from everyone who tried it, we knew it was going to have success on the shelves and we’d go forward with it.”

Below, Chaney answers questions about Sunny Crunch’s profile, BrightFarms’ development process and what crops are challenging to grow in a hydroponic system.

Produce Grower: What exactly is Sunny Crunch? And what was the inspiration for its development?

Nick Chaney: Sunny Crunch is a lettuce we began to develop in our system as an iceberg/green leaf hybrid. So, you get all the flavor and color of more nutritional lettuces, but it’s got that nice crunch that people like with the iceberg. The varieties we’re using for that were actually developed as head lettuces and we decided to try it out as a baby leaf. It has a much higher density and much shorter growth cycle and it came out performing very well.

PG: How does BrightFarms develop something like Sunny Crunch, and then bring it customers?

NC: It can develop from a couple of different avenues. We are in constant contact with our customers, [and] get feedback on what they want to see. As a team, we reach out to seed breeders and see what could be possible in hydroponics and order it all in. We run it through [our] system and see how it develops. If it works in hydroponics, and will be desirable to the consumer, we bring in sales, marketing, operations, our apprentice growers — everyone is involved — and go through stages of a crop’s feasibility in the greenhouse, its marketability and then take it from there. Something that is simple like a lettuce could get pushed through in two to three months, while something a little more complex [to grow] and isn’t ideal for hydroponics could take as long as six to seven months.

PG: What is an example of something that could take six to seven months to grow in hydroponics?

NC: I trialed mint. Mint had really struggled in hydroponics because it’s really slow growing and didn’t really have that strong flavor that it has in soil growing. But there’s an endless supply of genetics out there, so you just have to keep on pushing through and trialing and finding what works for both flavor and production.

This interview was edited for style and clarity.

The increase in soilless culture production of greenhouse vegetables, fruits and other consumables continues across the globe. As this rise continues, much research has been and is currently being conducted on suitable, alternative, economical, recyclable, disposable and efficient substrate materials to maximize crop yield and production efficiency. While the use of “soilless” organic and inorganic materials is not new to the industry, there is more interest in alternative materials now than ever before. Traditional (and successful) substrate components have included materials like rockwool, expanded clay aggregates, Growstones, perlite, pumice, Oasis cubes, coconut coir, peat moss and rice hulls. Another material that has been investigated is wood products (fiber, chips, sawdust, shavings, etc.). The goal of this article is to provide some background information and historical context to the development and use of wood substrates for controlled environment cropping systems. More detailed information about specific issues, potentials, advantages and disadvantages of using wood substrate materials will follow in the near future.

Wood fiber’s history

First developed in Europe in the early 1980s for the production of ornamental crops (floriculture and nursery), wood fiber has also been tested and trialed for vegetable and fruit production since the early 1990s. There are a variety of different wood components that have been commercialized over the years, many of which can have very different visual properties as well as physical and chemical properties (Fig. 1). To date, there have been more than 30 different types of wood substrate materials (components) developed, tested, and some commercialized in Europe and North America.

The idea of using wood materials can be alarming to many growers as we have been taught, or experienced, that there can be negative outcomes to growing plants in a non-composted fresh wood material. Research has shown that wood from softwood species (conifers) is better suited for use in plant growth systems because generally speaking, they do not break down (decompose) as fast as hardwoods, contain fewer phytotoxic chemicals than hardwoods, and they are located geographically around the world near horticultural production sites. Some conifer species studied in previous vegetable crop trials have included Pinus tadea, P. palustris, P. sylvestris, P. pinaster, Picea glauca, Picea abies, and Larix decidua.

Photo: Brian E. Jackson

Previous research with wood fiber substrates has been conducted on many vegetable crops in containerized or hydroponic systems including cucumber, tomato, peppers, cabbage, melons, herbs, squash, strawberries, cane berries and blueberries. These vegetable/fruit trials have spanned the globe as researchers in the United States, Canada, Spain, Poland, England, Germany, Belgium, South Korea and Mexico (as well as others) have contributed to our current understanding of the potential in wood-based substrates for crop production. Research has investigated using 100 percent wood substrates for crop production (Fig. 2) as well as blends of wood components to peat moss, bark or coconut coir.

Wood substrates currently on the market (commercialized) are primarily made by one of three main processes: 1) single or twin screw extrusion; 2) twin disc refiners; or 3) hammer mills. Each machine type and process is unique, therefore the wood fiber produced is unique. The differences among the different materials include fiber size and thickness, sterility/chemical properties, and varying abilities to be compressed, handled and blended with other materials. Companies who sell wood substrates should be able to provide the technical assistance to utilize and manage their specific product in one’s own production system. The structure and properties of different engineered wood fibers may also facilitate better or more specific usage in different cropping systems, loose-filled containers or troughs compared to compressed blocks or slabs, for example (Figs. 3 and 4).

When considering the switch to organic substrates or the switch to wood fiber in your production system, there are many variables to consider. As more intensive research is conducted, our understanding of how wood may be an option for you will become more certain. As of now, some potential advantages of wood substrate materials may include 1) organic in nature and OMRI (Organic Materials Review Institute) listed; 2) locally available to substrate manufacturers and growers, which could limit or lower transportation costs; 3) recyclable; 4) and disposable. Much remains to be learned about using wood components in our production systems, but the perceived advantages and potential are believed by many to be well worth their investigation and consideration.

Brian is an associate professor and director of the Horticultural Substrates Laboratory at NC State University. He can be reached at Brian_Jackson@ncsu.edu. More information about wood substrates can be viewed here