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Sustainability with GroGeo LLC
Subterranean greenhouse? Explain for me!
The facility itself is built into the ground, and if there wasn’t a roof on it, you’d fall into a 12-foot hole.The walls and floor are concrete with a glass roof, which pitches towards the south. Being mostly underground helps to maintain a consistent temperature in the grow space.
The idea itself comes from permaculture. There’s a structure called a “Walipini” that is essentially a subterranean greenhouse. We had some issues with airflow at first, so we started working on version two, which is what we’re currently growing in.
Tell me about the plants
We run a perpetual harvest system, and we harvest about 250 plants a week. In total, we have around 50 different strains. We hand water our plants with teas that we brew on-site. We even grow the plants that we use in the teas. We’re growing aloe, focaccia, comfrey, marigolds, and any other plants we can get our hands on.
What media and equipment are you using?
We currently grow in organic soil and use biodegradable plugs for our clones. The plugs eventually go into the compost pile. Because we’re in a subterranean greenhouse, we do need to use supplemental lighting and light deprivation depending on the time of year.
What automation and environmental controls are you using?
Most of our environmental controls are automatic or always-on. Our facility is designed with geothermal ventilation such that fans are constantly drawing air through the ground, which stays at a consistent temperature of about 60 degrees Fahrenheit. In addition to the geothermal fans, we have a bunch of fans that circulate air throughout the facility.
What pest issues have you had?
Back when Colorado was beginning its program, we accidentally bought some plants from some pretty horrible growers. The plants were covered in root aphids. We battled the root aphids for over a year, and eventually we decided the only way to get rid of the root aphids was to flush them out. We shut the whole greenhouse down, and it got up to 160 Fahrenheit for seven days, cooking the root aphids. We didn’t have that problem any more after that.
Nowadays, we mostly just face your standard fare of pests. If we run into issues, we quarantine the plant, and then use biopesticides such as predatory insects and teas to resolve the problem.
How does water management work for you?
The plants use up approximately 90-95% of the water we give them. Our “secret” is that we keep the environment nice and humid, so that the plants don’t need that much water in the first place. Right now, we’re in the process of tweaking our VPD with the goal of higher humidity and higher temperature. Our goal for our VPD is 90 degrees and 70% RH with supplemental CO2.
How do you utilize CO2 more efficiently?
Our facility was designed so that the CO2 has nowhere to go. The whole facility is solid concrete, and you have to take the stairs down or an elevator to reach the base level of the facility. The CO2 is kept at around 800-1200 ppm, so we’re well within safety standards for humans.
What does the electric bill look like?
When we built the facility, we considered setting up renewable forms of electricity generation. Our grow happens to be in a very windy area, which would be perfect for windmills. However, the cost would have ended up being a bit too high for our needs. Currently, we only run on a 200 Amp breaker, and we could probably survive on a 40 Amp breaker in the summer.
We’re getting charged about $2,200 a month in our electric bill for a 12,000 square foot grow. For reference, I rented my house in Tahoe to some growers, and they have a much higher electric bill for a smaller grow.
What was the cost of building a subterranean greenhouse?
It was actually very competitive pricing; it was almost comparable to building a commercial greenhouse. In my experience, Nexus greenhouses cost around $100 per square foot. Our subterranean greenhouse actually turned out to be around $80 per square foot. For us, digging a big hole and pouring concrete into it was cheaper than building an above-ground structure.
If somebody wants to grow sustainably like you, where should they go for more information?
I highly recommend any grower who is interested in our practices start reading up about permaculture. Permaculture is the core growing philosophy guiding our sustainable growing practices.
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Our plants are grown in organic soil that gets reused and recycled. We compost waste materials from the plants and even grow other plants to provide nutrients, including focaccia, aloe, and more.
The idea itself comes from permaculture. There’s a structure called a “Walipini” that is essentially a subterranean greenhouse. The goal of permaculture is to maintain a symbiotic relationship with nature, reduce waste, and use everything. We created our initial test grow, version one, based on the walipini. We’ve had some issues with airflow, so we’ve started working on version two, which is what we’re going to grow in. Our current grow measures 12,000 square feet.
We hand water our plants with teas that we brew on-site. We even make the teas ourselves, as we grow the plants that we use in the teas. We’re growing aloe, focaccia, comfrey, marigolds, and any other plants we can get our hands on year-round. Because we’re growing our own nutrients for teas, we don’t need to go to grow stores for nutrients.
Editor’s Note: Check out our related article on compost teas!
Because we’re in a subterranean greenhouse, we do need to use supplemental lighting depending on the time of year. We have 1000W DE HPS lights scattered throughout the grow. In the middle of winter, we run them all day long, but during the summer we barely run them. We also use light deprivation year-round, and it helps keep the heat trapped inside during the winter months.
During the summer, the geothermal fans keep the facility cool. In the winter, our light deprivation systems help keep heat stored inside the facility while it’s dark outside. Most of our systems rely on simple timers, although we are investigating other controllers.
Eventually we decided the only way to get rid of the root aphids was to flush them out. We shut the whole greenhouse down, including the fans. The greenhouse reached up to 160 Fahrenheit for seven days, cooking the soil and killing the root aphids and their eggs in the process. We didn’t have that problem any more after that.
Nowadays, we mostly just face your standard fare of pests. We maintain really good cleanliness protocols that keep out the pests. If we run into issues, we quarantine the plant, and then use biopesticides such as predatory insects and teas to resolve the problem.
Our “secret” is that we keep the environment nice and humid, so that the plants don’t need that much water in the first place. The dewpoint for our grow is 66 degrees. Right now, we’re in the process of tweaking our VPD with the goal of higher humidity and higher temperature. In the past, I wouldn’t have predicted it, but our three-feet-tall plants are growing buds that are almost as big as my head. Our goal for our VPD is 90 degrees and 70% RH with supplemental CO2.
Editor’s Note: Want to find out your grow’s dewpoint? Check out this nifty dewpoint calculator from the Image Permanence Institute.
The CO2 is kept at around 800-1200 ppm, so we’re well within safety standards for humans. Unsafe levels for people are over 5000 ppm. We have alarms that will go off if our CO2 level approaches dangerous levels.
We’re getting charged about $2,200 a month in the summer, $4,500 a month in the winter for our electric bill for a 12,000 square foot grow. If you know how expensive electric bills for grows can be, that’s really amazing. Some growers I know in California are paying $4,000 a month for a 1600 sq. ft grow.
The other thing I want to point out is that many greenhouses today are not designed for a cannabis grower. They are designed with a fruit and vegetable grower in mind. Fruit and vegetable growers don’t dump CO2 like we do. They don’t need light deprivation as much as we do. We designed our greenhouse explicitly for cannabis, and it really shows in the cannabis. I’ve had managers from well-renowned dispensaries go out of their way to get our cannabis. We’re located in Boone, Colorado, and dispensaries that could get cannabis from anywhere near Denver will reach out to us.
In the meantime, I highly recommend any grower who is interested in our practices start reading up about permaculture. Permaculture is the core growing philosophy guiding our sustainable growing practices.
Editor’s Note: Stay tuned to Growers Spotlight for relevant educational information as well!
About Anthony and GroGeo
Go green, baby.Anthony Mollins
Eventually some friends of mine wanted help making their own grow rooms, and I made a business out of it. We ended up designing 35 different grow operations. My wife and I started Tahoe Herbal Care and ran it until 2014 when we sold it. I gained all sorts of experience in indoor growing, light deprivation, and more.
I decided to move back to Colorado and started working on a sustainable greenhouse. I had an idea floating in my head about a subterranean greenhouse. I traveled around for several years, researching permaculture at different communes, and I realized that I was the only one thinking about a subterranean greenhouse for cannabis. I decided to build it because I wanted a sustainable practice.
One other issue that we have is due to our location. Our grow is located in Boone, Colorado, which is located pretty far out in rural Colorado. It’s a very small town, and many of my the neighbors work for me. Finding talent can be particularly tricky.
The said, growing in Boone has been a, well, boon. They’ve welcome the grow with open arms because it is sustainable, clean, and not an eyesore like many other grows. Out of sight, out of mind.
Additionally, we are actually showcased as part of Willie’s Reserve. And there’s been lots of little successes along the way, such as finishing construction on the facility, growing amazing cannabis, and more. As I mentioned before, I’ve had people go way out of their way to buy my cannabis.
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- Want to figure out the dewpoint for your grow? Check out this handy calculator from the Image Permanence Institute.
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About the Author
Hunter Wilson is a community builder with Growers Network. He graduated from the University of Arizona in 2011 with a Masters in Teaching and in 2007 with a Bachelors in Biology.