Ask the Budding Botanist: what are hydroponics in cannabis?

With more states legalizing cannabis, interest in cultivating the plant continues to rise. And while cannabis may grow like a weed, it takes time, care, and consideration to craft top-shelf buds.

GreenState knows that people have lots of questions about growing cannabis. To help take the guesswork out, professional cultivator Kurt Kinneman, owner of Kinnektion Farms, is here to answer your budding queries. From seed to smoke, GreenState has you covered.

RELATED: Ask the Budding Botanist: how can you tell a male cannabis plant apart from a female?

Question: what is hydroponics in cannabis?

Hydroponic growing is any cultivation technique that uses water to deliver nutrients instead of soil. The root system is supported in a grow media such as rock wool, coco coir, expanded clay pellets, peat moss, perlite, or any other porous, well-draining material. The benefit of a hydroponic system versus soil is constant delivery of nutrients vital to plant growth.

The nutrient solution that is supplied to the plant requires pumps and valves to move it through the hydroponic system. It also requires monitoring to ensure the plants can easily uptake the nutrients that are suspended in the water. Hydroponic systems take a lot of maintenance and monitoring to ensure they work properly.

How water is applied to the root system determines what type of hydroponic system is being utilized. Roots can be supplied a nutrient solution using an ebb-and-flow system, a deep water culture system, or an aeroponic system.

Ebb-and-flow system

An ebb-and-flow system uses a medium like rock wool or coco coir to support the root system. The medium is saturated and allowed to drain or dry back multiple times throughout the day. These events are timed to allow the media to dry back in between waterings and prevent the roots from becoming oversaturated. When the medium is saturated, new nutrients can be introduced into the roots. 

Deep water culture

In deep water culture (DWC), root systems are suspended in an oxygenated nutrient solution. The plants are supported using expanded clay pellets and net pots. Specialized containers are used to hold the net pots above a large reservoir, and the roots are suspended in a nutrient solution. Nutrient film technique (NFT) is a similar technique where roots are suspended above a flowing nutrient solution.


Aeroponics uses pumps and specialized spray nozzles to apply an ultra-fine mist to a plant’s root system. The root system is suspended above the spray nozzles using net pots and media like expanded clay pellets or rock wool. The fine mist that is applied to the root systems allows for more oxygen around the root system, which greatly benefits the plant.


Aquaponics involves growing fish and plants in the same water. Water from fish tanks is pumped through specialized filters to remove waste solids and leave nutrient-rich water. The water is then delivered to the plants in an ebb-and-flow or DWC system. The plant’s roots will absorb the nutrients from the water, which can then be delivered back to fish tanks as fresh, clean water for healthy fish!

What nutrients are used in hydroponics?

Nutrients for hydroponic systems come in liquid bottled form or as dry salts that have been carefully crafted for easy uptake by a plant’s root system. Liquid nutrients can be derived from chemical or organic sources like fermented plant extracts and compost teas. When using compost teas in hydroponics, care must be taken to ensure particulate matter is filtered out of the water to prevent damage to water delivery systems. 

It is important to follow manufacturer mixing instructions to ensure elements don’t fall out of the solution. When nutrients fall out of the solution, they cannot be absorbed by a plant and form precipitates in the solution. When precipitates appear in a solution, nutrients are wasted, and the particulates can cause damage to watering systems.

Maintenance and monitoring

Hydroponic systems must be meticulously maintained to prevent unwanted bacteria build-up and line clogging. Moving water is a critical component in any hydroponic system, so ensuring lines and filters are not clogged is part of everyday maintenance. 

Monitoring is crucial to ensure that water parameters are maintained to allow root systems to absorb nutrients from the water efficiently. Key parameters are pH, electrical conductivity, total dissolved solids, and temperature. 

Hydroponic growing requires a pH of 5.8 to 6.2 and water temperature in the low 60’s. The electrical conductivity and total dissolved solids indicate the nutrient load of the water and are adjusted based on a plant’s stage of growth. Cultivators can use handheld sensors to monitor water conditions. Sensors can also be integrated into monitoring systems for 24/7 data logging. 

Hydroponics in cannabis: water, water everywhere

Hydroponics is the art of growing with water solutions.  Well-draining grow media is used to support the root system and allow nutrients to be absorbed by a plant. There are many different hydroponic systems with all levels of complexity, but the most important part of any system is its maintenance and monitoring. Any change in water conditions can drastically affect a plant in a matter of hours, so tread lightly when considering hydroponics! 

This article was submitted by a guest contributor to GreenState. The author is solely responsible for the content.


Kurt Kinneman is a cannabis cultivator and owner of Kinnektion Farms. He is also a horticultural engineer at AI Grow, a provider of automation solutions for controlled environment agriculture. In addition to cannabis, Kurt also grows pumpkins on his family farm.