While there are many ways for indoor and greenhouse cannabis growers to be sustainable, few grow types are more environmentally friendly and inexpensive to run than an outdoor, closed-loop farm, where everything used on the farm goes back into the land. For example, plants are grown on the farm to be used in nutrient mixes, composts and pest repellants, while excrement from the farm’s alpacas are used in compost.
Many commercial cannabis growers shy away from such systems, however, figuring they aren’t viable on a commercial scale. To be sure, accumulating enough worm castings and ingredients from your garden for nutrient composts and organic sprays for 1,000 plants sounds daunting.
But not only can it be done, it’s simple, said Mark Simpkins, chief cultivator at Sacred Flower Farms, the company he started on a former 16-acre pear farm in southern Oregon.
People don’t believe this can be done on scale, but “that’s simply not true,” Simpkins said. “We ran 1,400 outdoor plants, about 20,000 square feet of canopy and brought in nothing. Almost all our ingredients were grown onsite.”
Sacred Flower, for example, gets almost all its ingredients for soil nutrients and pest and contaminant control from a diverse army of plants and flowers, as well as five alpacas.
“We’re constantly striving to close as many loops on our farm (as possible), and what that means to me is to be self-reliant and have as many things growing onsite that we can use for our cannabis farm,” Simpkins said.
While Simpkins grows seasonally outdoors, he said many of these techniques can be used indoors or in greenhouses as well.
Securing Water
For Simpkins, the first step to establishing Sacred Flower was finding property where he could secure water rights. The solution: In 2016, he found a former 16-acre pear farm that was on a reservoir serving local agricultural businesses.
Simpkins has a commercial-grade, one-horsepower pump that can pull the water from the reservoir through hoses that run 30 yards through a multilayered filter system – it includes charcoal and sand filters, among others – to four, 2,500-gallon stainless steel storage tanks.
Two are brew tanks where he can make compost tea. One also has a large aerator, allowing Simpkins and his team to pour strained ferment into it to aerate for a couple of hours. The tanks are then opened to feed drip lines that run through the farm’s 24 cannabis beds. Each bed contains about 60 plants.
Simpkins’ drip irrigation system of choice is Netafim, an automated pressure-regulating drip irrigation system that he said doesn’t clog – a common problem with organic nutrient mixes. Simpkins said the pressure is set at 40 pounds per square inch so that each line can put out 18 gallons per minute for each bed.
“We run four of those lines per bed so that we’re making sure the entire bed is getting moist,” Simpkins said. Any runoff, he noted, helps – not harms – the environment.
“The way that we feed the plants and what we feed them is providing beneficial runoff as it runs through the soil, even in areas where the ganja isn’t,” Simpkins said. “It’s all good stuff. It’s nothing harmful. Everything we’re putting out there isn’t just safe but making things better.”
Simpkins said the Netafin system cost $58,000, and the pump, filters and tanks cost $49,000.
To keep that moisture in the ground and reduce the chance it will be lost to evaporation, Simpkins uses mulch and rice straw – the latter being one of the few products not grown at Sacred Farm.
Specifically, he top dresses his main layer of soil with mulch. Last year, he brought in 160 bales of rice straw and spread six to eight bails on each of the 24 cannabis rows. That protected the soil from overheating during the summer and freezing over the winter.
“It really holds a ton of moisture down where you want it. If you dig down, you’ll find a ton of moisture underneath the soil where you want it, even on 100-degree days,” Simpkins said. “When you employ methodologies like heavy mulching, you dramatically cut your water needs. And you’re keeping that soil alive because that top layer never dries out. That allows worms to come up and provide their castings on the top layers of the soil to keep things rich and alive.”
The next step in Simpkins’ water strategy is building a rainwater catchment on the roof of his 4,000-square-foot barn.
Improving the Soil
After Simpkins picked his farm, the next step was laying a foundation of top-shelf soil. He chose Plant Your Root, a company in Eugene, Oregon, that makes high-end soil that usually sells for about $200 per yard. Simpkins got a deal on some less-custom soil for $130 per yard, figuring he could add some ingredients himself.
The soil starts with a base of one-third peat moss, one-third compost and one-third aeration ingredients, like pumice and lava rock. The compost is made from many ingredients, including fish compost, organic mushroom compost, organic dairy cow compost, vegetable compost, worm castings and bug excrement.
The idea is that this is a one-time investment and the organic nutrients and the beneficial bacteria will improve the soil over time.
“Hopefully it gets better every year as we give more love to the soil,” Simpkins said.
For example, every year Simpkins and two employees top dress the soil with 5 yards of worm castings plus alpaca manure; they then add a top layer of mulch. Alpaca manure contains numerous trace minerals that are vital to cannabis, and it’s also high in nitrogen and potassium, according to Simpkins.
“Every year, more organic matter is going into that soil, keeping it alive and thriving,” he added.
Whipping Up Nutrients
Almost all the nutrients that Sacred Flower puts into its cannabis are so-called dynamic accumulator plants that are grown on the farm. Such plants have root systems that go deep into soil and draw nutrients back into the leaves.
One of Simpkins’ favorites is comfrey, which is rich in key nutrients, including nitrogen, potassium, calcium, magnesium and iron. He also likes stinging nettle for its high levels of nitrogen, calcium and potassium.
“These are very powerful plants that have produced great results for us,” he said. ”We’ve been able to keep things incredibly clean. No bottled nutrients or pesticide or fungicide.”
However, plants that are high in nitrogen during flowering stage are not ideal, so comfrey and stinging nettle are out. Marigolds, meanwhile, are high in phosphorous and potassium, making them a good choice.
To make nutrient ferment, Simpkins cuts down whole plants he plans to use and chops them up. The chopped leaves are mixed with a roughly equal amount of brown sugar, which helps release moisture in the plant and acts as a food source for the beneficial bacteria. Through osmotic pressure, the mix releases “a ton of moisture.”
To kick that moisture into fermentation, he uses something called Bokashi bran, which is Bokashi inoculated with EM1, or effective microorganisms, a slew of beneficial bacteria contained within the dry bran. Simpkins typically ferments the mix for about three days and strains it through a cheese cloth or cider press. That removes any clumps and ensures easier passage through drip irrigation hoses.
Simpkins generally doesn’t add water to the mix, so it’s a very concentrated solution. When it’s time to feed, the dilution rate is usually between 500 and 1,000 parts water and one part fermentation solution. Simpkins estimates that putting
3 gallons of ferment into one of the 2,500-gallon water tanks is sufficient.
“A little goes a long way,” he noted.
After the ferments are done, he stores them in 2-gallon and 5-gallon buckets with lids. The sugar in the mix works as a preservative, so there is no need to refrigerate.
Simpkins doesn’t have a set feeding regimen; instead, he observes the plants and gives them the ferments Sacred Flower has on hand. Generally, however, Simpkins runs the ferments through the irrigation lines at least once per week, sometimes twice, depending on what he has stored.
Taming Pests and Disease
Sacred Flower’s pest and disease control program also depends on farm plants and incorporates predatory bugs that prey on pests.
As with Sacred Flower’s nutrient plan, farm plants are used to make ferments that can be used in sprays to keep pests off plants and protect against disease.
When it comes to repelling pests, Simpkins said they hate strong smells, so he grows several different fragrant herbs – including peppermint, lemon balm, lavender and rosemary – that can be fermented, diluted with water and used as a foliar spray. He also makes a ferment from jalapeno and habanero peppers.
Simpkins uses the same process to make the pest-prevention sprays that he uses to concoct nutrient ferments. When using the mix preventatively, he dilutes it by about 1,000 parts water and one part mix. If he spots pests, the mix will be stronger, diluted by 100 parts water and one part mix.
“Those really potent, strong-smelling herbs really help drive bugs away. They don’t like those intense smells,” he said. Next season, he plans to try companion planting these fragrant plants in marijuana beds to deter pests.
Once the plants hit a certain size, or get into flower mode, Simpkins stops spraying and instead introduces predatory bugs.
“Once you get to a certain size, foliar spraying becomes far less effective because you really need full coverage,” he said.
Simpkins found a non-GMO predatory bug supplier, Natural Enemies in Clackamas, Oregon, from where he mainly gets Amblyseius andersoni and Amblyseius swirskii predatory mites to fend off Russet mites.
They come in slow-release sacks with a cardboard hook that you can attach on a stem. One per plant is ideal, Simpkins said, but having one on every other plant often suffices for prevention. You should reapply the sacks every three or four weeks, Simpkins said.
Simpkins said Sacred Flower spends $7,000 to $10,000 per year on predatory bugs, making it one of his biggest expenses.
And if a cultivator can say their biggest expense tops out at $10,000, they’d be pretty pleased, considering many growers spend 10 times that much or more on electricity, or 10 times that much or more on nutrients, and other cultivation necessities.
There’s also something to be said for cannabis grown in a closed-loop system.
“The more you can do it in tune with nature, the better the product is going to come out,” Simpkins said.
“It’s not extremely difficult,” he added. “It’s just having fun in the garden.”
– Omar Sacirbey
