The amount of water you need will depend on your region's climate, the growth stage of your hemp plants, and your irrigation system. As mentioned, drip irrigation requires the least amount of water, but you will still need between two and three gallons of water per plant per day during peak growing season. At 900 gallons per plant per season, 26,000 plants use 23,400,000 gallons per season (3.1 million cubic feet of water). Twenty-three million gallons would mean that 12 inches of water falling on 71 acres would provide enough water for Outlet Creek Valley's entire 65-acre cannabis crop, provided it is properly harvested and stored in the rainy season for use in the dry months.
Even in dry years, Mendocino gets about 40 inches of rain, and Outlet Creek Valley covers 103,616 acres, according to Fish and Wildlife. Hemp is not as immune to drought as its supporters claim, according to a soil researcher at Colorado State University who analyzed two years of Colorado hemp production. Hemp has great potential to compete with crops such as corn, cotton and soybeans, but as the industrial hemp supply chain builds, those crops are not going anywhere, Campbell said. Purdue University's Hemp Project reports that most hemp varieties need between 25 and 30 inches of rain a year, especially in the first few weeks of life.