Author & Interviewer: Karim Tinoco, Program Manager for Sustainable Foods & Kitchen
Only 4.4 miles away from campus, Pure Green Farms is an indoor hydroponic farm committed not only to freshness but to creating a sustainable system that can produce tasteful leafy greens year-round. Spanning across 65 acres, this cutting-edge facility boasts a 3.5-acre greenhouse and a 52,000-square-foot headhouse, revolutionizing the way we grow and consume produce. In this interview, we will take an exclusive tour inside this high-tech controlled environment agriculture (CEA) facility, where we meet CEO Joe McGuire to learn about their groundbreaking approach to farming.
The Journey From Seed to Plate
As we put on the required PPE and stepped into the greenhouse, Joe explained to us Pure Green’s in-house processing and the sourcing of their materials:
JM: Everything starts and finishes here. We plant the seeds here, we grow them hydroponically, we harvest here, we package here, and then we ship out. From beginning to end, A to Z, it all happens here.
KT: What is brought in?
JM: We bring in things like our peat growth media, which is a substrate that holds your seed before it cracks and starts to establish roots. We also buy carefully selected seeds from European breeders that are specifically tailored for hydroponic growth. We bring in other elements, such as nutrients, and then, of course, water.
KT: Where does your water come from?
JM: Right underneath our feet! We were standing on a giant aquifer, so we've got tons of water! Northwestern Indiana, overall, has a lot of water. But this particular area was formally wetlands, known as the Grand Kankakee Marsh, which still feeds the Kankakee River that essentially goes into Lake Michigan. Therefore, we use only well water for all of our irrigation. We then run it through a reverse osmosis system to clean it out of any minerals and substances that we don't want in it. But, by and large, it's clean water! However, we still test it daily and send it to a separate lab two times a week just to make sure there's no contaminants in it.
KT: What do you do with all the runoff water once the plants are irrigated?
JM: I know it is hard to tell, but all the tables are actually pitched downward at a 3-degree angle. The reason for that is that we want to use gravity to have the water flow down without having to use any energy. Then the building itself is pitched to the southwest corner for the same reason. This essentially allows us to recapture all of the water that is not absorbed by the plants and reuse it, which accumulates to approximately 40,000 gallons of recycled water a day. This water is incredibly valuable, you see. It’s filled with nutrients, and that’s something we want to keep as much as we can. You don't want to throw it out!
KT: So, how does the system work?
JM: The system itself comes from Finland, so anyone can buy it really, but operating it is a completely different matter. These are what we call gutters, which are 18 feet long and about two inches wide. They hold all of our plants. As you can see, there are 19 lines which enter into the greenhouse and are automatically pushed into their designated place by a computer system with belts and sensors that let us know if any jams or dealignment occur during this process.
For the first two days, you want to keep the seed in a dark and damp place, which is at the back end
of the lower level. As the seeds complete germination, the gutters are pushed northward into the LED lighting area, where the plant growth continues. It is crucial that the lights are directly on top of the plants so that they do not waste energy trying to reach the light. This is what will allow you to grow robust and stubby plants that give you that crisp when eating a salad.
After approximately five days, the gutters continue to move northward and then get taken by an elevator to the top level.
KT: Is the rest of the operation done by natural light then?
JM: Exactly! So as you can see the shades are down right now, that is because we want to be careful not to have too much energy in here. Basically, we don't want to get too hot. The shades are also run by a computer system which is constantly adjusting the amount of light we let in. Of course, there are cloudy days and short winter days to account for too. Those days, we are forced to turn the lights on to ensure our plants are well-fed. That's our biggest energy consumer honestly, which is why we try to use as much natural light as possible.
KT: You mentioned winter, how are you able to keep the ideal temperature through the cold?
JM: So, at the entrance, you should’ve seen a large water tank. That’s our hot water storage, which holds 260,000 gallons of hot water. That hot water is then run through pipes all around the greenhouse keeping the ideal temperature. It kind of works like your old school radiators at home.
It's the most efficient way of doing it, but the best thing about it is that it doesn’t make the air overly dry. You don't want it overly humid either but you definitely don't want it dry in here! Dryness will destroy your plants.
KT: How do you maintain that balance of humid vs dry?
JM: One of the most crucial tasks to address here involves managing the airflow effectively. Towards the far end, you'll notice the climate corridor running along the wall. This extensive passageway spans from north to south and serves as the conduit for regulating our indoor climate.
The mechanism involves generating our own climate and propelling it through this corridor. This process is facilitated by a series of 73 large box fans positioned at the base of the corridor. These industrial-grade fans operate incessantly, 24/7, creating a continuous stream of airflow. They are interconnected and play a vital role in driving air through the conspicuous white tubes underneath the corridor.
These tubes, if observed closely, feature openings on the sides that emit air. The primary objective is to push the air through these tubes, allowing it to rise. Although the system isn't flawless, it represents the cutting-edge technology within the industry.
An added benefit of this setup is that as the air circulates and passes through, it carries a fine mist, which effectively reduces the temperature. This cooling process is particularly efficient in arid and dry climates, and it significantly contributes to maintaining the desired climate within the space.
Meticulous efforts are employed to uphold the optimal climate conditions. Consequently, a significant amount of my family's time is dedicated to ensuring that the climate within the facility remains as close to perfect as possible.
KT: How important is flavor?
JM: Oh, it's everything! Once you lose the flavor you lose the magic of the lettuce. You wanted nice and sweet, but also crunchy, that's just as important. Have you had our salad yet?
KT: I eat it every day in the dining halls. I'm not joking! It is always sweet, never bland, and so crispy. That must be from the lighting placement you spoke of before.
JM: Yes! But it also has a lot to do with the nutrients. You see that beautiful sheen right there? Shiny right? That means the plants are really eating up the nutrients making it nice and healthy. I didn't know about it until we had a horticulturist come in here and inspect our lettuce.
KT: Do you ever need to spray the plants with any chemicals?
JM: We never spray our plants with anything ever. No pesticides, no herbicides, zero! We don't need to! That's the beauty of a controlled environment. All we feed our plants is clean water and nutrients; that's it. We then recycle that nutrient-filled water and start the whole process again and again. That's how you get big healthy plants.
KT: For you, what is the most exciting part of growing in a controlled environment like this one?
JM: I don’t have anything against the field business. I myself come from the field business, we are very blessed to have a food structure as productive as the one we have in this country. But I think we should always try to make that structure better. That's what it’s all about. We just want to make local fresh food more sustainable. This system allows that; we don’t have to use pesticides, we don't have to use herbicides, we don't have to worry about nutrient leaching or degrading our solid. We just don't have those problems, sure we get some bugs in there but in a controlled environment, that is much easier to deal with. That’s what makes it different, the control we get.
Originally published by at green.nd.edu on November 14, 2024.