A basic hydroponic setup, deep water culture (Amy Phung/Leafly)

A method of growing cannabis plants using water as a medium, rather than soil. In hydroponics, roots are suspended in water and water not initially absorbed gets recycled through the system for later use.

“My friend grows some hydro that is absolutely killer.”

“Growing hydroponically is cleaner because you don’t have to mess around with soil.”

What is hydroponics?

Hydroponic cultivation suspends cannabis plant roots in water, instead of using soil as a grow medium. There are several types of hydroponic systems, including deep water culture (DWC), ebb and flow, drip, and more. Hydro systems typically involve a chamber or tray to house plants, which is filled with nutrient-rich water. Roots can either be continuously suspended in water, or flooded with water at intervals, and then left to dry out, depending on the system. Often, hydroponic cultivation is done using cloned cannabis plants, rather than seeds.

Hydroponics allows the grower more control over plants, as the growing medium (water) can be regulated more easily than soil or other mediums. Because of this, weed grown hydroponically is typically of a higher quality. However, these setups tend to require more labor as you constantly have to check the pH and ppm levels of the water and nutrients. In addition to extra labor, a hydroponic system will likely be more costly to set up, and will require more skill and knowledge.

The history of hydroponics

Humans have been experimenting with some form of hydroponic cultivation for thousands of years, going back to the Hanging Gardens of Babylon and the chinampas of the Aztecs. Modern hydroponic cultivation started in 1929 with William Frederick Gericke at the University of California, who was able to grow a 25-ft. tomato vine using hydroponic cultivation. 

Recent research suggests a benefit to hydroponics is that “Compared to the soil-based system, the hydroponic system provides a more homogeneous nutrient medium to the plants with less risk of soil-borne diseases.” But research is more divided on water efficiency of hydroponic cultivation: While a 2019 white paper by the Massachusetts Cannabis Control Commission notes that “Hydroponically grown cannabis is much more water intensive than other crops,” a 2017 study argues that they use much less water than traditional growing systems.