Conserving water has become increasingly important for cannabis farmers, particularly those in regions facing drought, water shortages and/or municipal restrictions.
Many farmers have succeeded in reducing their water usage with rainwater-catchment programs and water-recapture and recycling systems.
But a small number of cannabis farmers are going a step further by not watering their plants at all using a practice called dry farming.
Native Americans have used dry-farming practices for thousands of years, and more-modern dry farming dates to the 19th century.
But with most of the Western United States experiencing a historic drought, dry farming is becoming less of a novelty in the 21st century and more of a necessity.
Necessities From Below
On the surface, not watering your marijuana plants seems like a death sentence. But lack of irrigation is only one part of dry farming. The far more important part is making sure there is enough groundwater in the soil for your plants to feed on.
“With dry farming, the water is down below. And you want to bring the water up the soil profile to the surface,” explained Sunshine Cereceda, the owner of Sunboldt Grown, who has been dry farming since 2016 on about 10,000 square feet along the Eel River in Humboldt County, California.
Cereceda grows about five strains and currently sells to two dispensaries. She is working on getting two more clients for next year.
Proponents of dry farming understand the skepticism it faces. But having mastered the practice, they say it’s not only possible but yields a superior product—one that is at least as potent and more flavorful because the plants can access soil nutrients that haven’t been watered down.
“At harvest, I don’t have excess water in my bud. It just dries and cures really nicely,” Cereceda said, adding that water dilutes cannabis flower. “The idea (of dry farming) is that by having less interference with the growing of the plant, you’re going to just get more terroir. You’re going to get more taste of the place and the genetics.”
Location Is Paramount
Dry farming is not for everyone, nor is it possible everywhere. And Cereceda credits part of her success to the location of her farm.
“I’m in a unique region where it’s most likely a combination of geology and soil texture,” Cereceda said. “The water table can actually be quite deep.”
Sunboldt Grown Farms sits on a floodplain near the Eel River atop a clay silt loam—soil containing at least 70% silt and clay and at least 20% sand—a composition that is especially conducive for allowing water to flow. Because Sunboldt is on a floodplain close to the Eel River, there is already a significant amount of groundwater.
In addition, the Eel River floodplain where Sunboldt is located sits on flat ground at the bottom of a hill, so rainwater and snowmelt naturally flow down into the farmland, infusing the soil with even more water.
“We’re like a big rain catchment on the flat,” Cereceda said. “And when I dug the hole (while considering dry farming), I felt that it wasn’t wet, but it was moist.”
Water Through the Soil
One advantage of dry farming, Cereceda said, is that it’s easy to begin a crop.
“I can take clone cuttings right out of the clone tray and put them right into the ground and water them once or twice and then just go to dry farming. It’s really efficient to be able to do that,” she said.
Cereceda likes to plant in June, after she’s had an opportunity to till the soil.
Tilling the surface—she goes well over a foot deep—opens up “the soil capillaries” and allows groundwater to reach where cannabis roots can absorb it, she said.
“You scrape the soil, and then it wicks the water up to the surface on the hottest days,” Cereceda explained. “When the ground is getting the hottest, there’s more moisture in the soil. It’s a little counterintuitive. It’s not a top-down thing. It’s a bottom-up thing.
“It’s probably done by evaporation. The ground gets hot and there’s water evaporating (and moving toward the surface). As it evaporates, it cools more,” she said.
Having a location with a high water table and silt loam will encourage successful dry farming, but dry farmers should take other steps to stretch out the water available to their plants, most notably using a compost-based fertilizer, which helps the plants absorb nutrients.
Dry farming also has its negative aspects, Cereceda said. One is that there is nothing growing in between the rows of marijuana plants, meaning that soil is bare and more susceptible to erosion. Also, the tilling—especially rototilling—required to open up the soil capillaries destroys the soil structure and soil biome, Cereceda said.
“There are some issues with dry farming. Yes, it’s great not to use water. But are we compromising our soil? What’s more important, not using water or conserving soil? I’m kind of leaning towards preserving soil,” she said. “So I’m looking for ways to dry farm where I won’t have so much bare soil and I also can be lighter on the tilling and yet still have water and move up the soil profile.”
One change she’s made that’s offering promise is switching from a rototiller to a roto-spader. The difference is that a rototiller “pulverizes” the soil, damaging the soil structure, Cereceda said, while a roto-spader does a better job of “maintaining the soil aggregates,” which are “the glue that holds the soil together.”
She also is considering spreading woodchips over the barren areas between rows with the hope that it will combat soil erosion while keeping the soil capillaries open.
Despite dry farming’s challenges, Cereceda believes she can make adjustments that will help her maintain soil quality while continuing to dry farm.
“Traditionally, cannabis growing takes so much water. It takes a lot of water to grow big plants. And so, for me, I’m making a choice to grow lower yields and use less water. Cannabis being grown with really intensive agriculture, I think, is just not necessary,” she said.