A cultivation method that uses sand, gravel, or, most commonly, water, with added nutrients, rather than soil.  Liquid nutrients are added directly to growing media such as coco coir (coconut husk fibers), clay pebbles, or another lightweight, expandable aggregate to replace soil. Hydroponic cannabis gardens are considered more efficient than traditional soil-based gardens, as the open-root system allows for direct uptake of nutrients and oxygen.

He wanted to grow plants year round, so he decided indoor growing using hydroponics was the right cultivation method for his cannabis business.

There are multiple methods of hydroponics — the best one for you will depend on your budget and level of experience.

cannabis hydroponic growing Photo by: Gina Coleman/Weedmaps

Origin of hydroponics

Hydroponics is used to describe this particular cultivation method, which uses another growing medium instead of soil to deliver nutrients to plants. .

The use of hydroponics is believed to date back to 600 BC, where the cultivation method was used in the Hanging Gardens of Babylon. Hydroponic techniques were  also used in the 10th and 11th centuries by the Aztecs to grow crops at Lake Texcoco, and references to hydroponics were found in the writings of Marco Polo following his exploration of China in the late 13th century.

Hydroponics is widely considered to be a more effective cultivation method than soil-based gardens because it allows water and other nutrients to be applied directly to the root — as opposed to soil-based gardens, where water and nutrients are absorbed through the soil. This allows roots to access the nutrients without having to “search” through the soil—which can result in larger, healthier plants.

Hydroponics vs soil

There is a growing body of research suggesting that hydroponic agriculture is a more efficient and reliable method than traditional cultivation in soil. For example:

  • A study published in 2015 compared strawberries grown in soil to strawberries grown hydroponically. This project found that, although soil produced the largest individual berries, the “hydroponic strawberries were higher in terms of fruit yield and plant survival rate.” Additionally, the hydroponics setup also produced fruit that was more consistent in terms of size.
  • Another 2015 study concluded that hydroponics is a promising technique with great potential for high-efficiency agriculture. Researchers noted that there are still too many energy inputs required to make hydroponics significantly better than soil on a large scale, but suggested that technological advancements could fix this. At that point, large scale hydroponics agriculture would become much more efficient than soil-based agriculture.
  • A 2018 study showed that hydroponic agriculture has a higher growth rate than soil-based agriculture, and concluded that hydroponics could be a promising way to grow plants more efficiently than growing them in soil.

Advocates of hydroponic farming argue that hydroponic techniques produce a better final products, as they provide much more control over the growing environment. Additionally, hydroponic techniques are often more efficient than growing in soil because they require fewer inputs and use only what's needed to feed the plant. There is very little—if any—waste, whereas growing in soil requires many more inputs and a much larger portion of those inputs (plant food, fertilizer, water) go to waste in the soil. At this point, the only real downside to hydroponics is that many setups are indoors, which requires a lot of energy for lighting and ventilation.

When it comes to the final product, the hydro vs soil debate is a matter of preference. Some say that plants grown hydroponically are better quality because they were grown in fully controlled environments. On the other hand, many claim that plants grown in soil have a more complex set of flavors and tastes—something like the “terroir” that wine lovers talk about—that come from the unique environment in which a plant grows.

What is hydroponic cannabis?

Simply put, hydroponic weed—often called hydro weed—is cannabis grown using a hydroponic method. Typically, hydroponic weed is grown indoors in a fully controlled environment. This approach gives cannabis growers complete control over the plants' environment, which can produce more reliable crops, more consistent buds, and faster harvest cycles.

How to grow hydroponic weed: Common hydroponic techniques

To grow marijuana hydroponically, it's important to understand the various techniques used by successful growers. There are many systems that fall under the hydroponics umbrella, since it encompasses anything that's soilless and provides oxygen, water, and nutrients to plants. With that in mind, this simple hydroponics cannabis growing guide outlines some of the more popular techniques:

Deep water culture

Arguably the most simple of all hydroponics systems, the deep water culture technique is popular with beginners or cultivators looking to keep costs low. 

In this technique, each plant is placed in a separate pot or container. Thecontainers are then placed in a tray and water added to submerge the roots. If the containers have the ability to hold water individually, the tray is unnecessary.

Nutrients are added to the water, which is kept oxygenated using air pumps, allowing the roots to remain submerged.

Wick system

The wick system is another hydroponics technique favored by beginners due to its simplicity. With the wick system, plants are placed into a container over a reservoir containing nutrient-filled, oxygenated water. One end of a wick, which could be constructed from any absorbent material like cotton or cloth, is placed in the reservoir while the other end is placed in the container. The wick acts as the delivery system, drawing up nutrients and water to feed plants.

Nutrient film technique

Similar to deep water culture, nutrient film technique involves continuously submerging the roots of the cannabis plant in water. However, nutrient film-grown plants are placed in a “planting tube” (typically constructed from PVC piping). Oxygenated water containing nutrients is pumped from a reservoir into the tube. The tube is placed at an angle, allowing the water to flow through the tube and soak the roots of the plant before draining back into the reservoir.

Drip system

Drip systems are popular with commercial growers because they allow for better control of the amount and frequency of nutrient solution delivered to each plant. With a drip system, each plant has its own individual water jet through which the nutrient solution is delivered using a time-controlled pump. Any excess solution is then collected back in the reservoir through the recovery system.

Ebb and flow/flood and drain

The ebb and flow system, also known as flood and drain, is unlike other systems in that it doesn't keep the roots of the plants constantly submerged in water. Instead, the grow tray is flooded with the nutrient solution. After the flooding, the nutrient solution is then drained back into the reservoir, exposing the plants to oxygen before repeating the process again.

Materials needed for hydroponic growing

While the materials will vary based on hydroponics system, there are a few materials necessary for all hydro weed operations, including:

  • Seeds or clones
  • Nutrients
  • Containers for the plants
  • Potting medium (such as clay pebbles or coco coir)
  • Grow lights
  • Water pump
  • Aquarium air pump

Ideal pH levels for hydroponics nutrient solution

One of the largest contributing factors to successfully growing hydroponic weed is the pH level of the nutrient-filled oxygenated water solution. In order for plants to be healthy, the pH of the solution should be kept slightly acidic, between 5.5 and 6.5 pH. The exact pH level will differ, depending on the stage of growth. There are a number of products on the market to help growers accurately measure pH levels.

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The information contained in this site is provided for informational purposes only, and should not be construed as medical or legal advice. This page was last updated on July 13, 2021.