What is hydroponic marijuana? Is it better?

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Hydroponic marijuana is grown in a highly-controlled, indoor grow system that does not use soil. These systems use water (hydro), nutrients, and a soil-less growing medium to get the job done. A nutrient solution comprised of water and dissolved, inorganic fertilizers is directly supplied to the plant roots.

The most common soil-less mediums used for hydroponics grows are coco coir, rockwool, hydroton, perlite, or vermiculite. Growers may use one or a combination of these media to provide support for the roots.

Hydroponics grows are high maintenance, so we don’t recommend them for the novice grower. However, the control they offer with the decreased need for pesticides makes them a compelling option for cannabis growers with some experience under their belts.

Hydroponics is Nothing New

In a 1982 Journal of Plant Nutrition review, Professor J. Benton Jones, Jr. reports that the use of hydroponics systems can be dated back to the mid-18th century, though he concedes that the use of nutrient rich water to grow plants is likely as ancient a practice as human civilization itself.

In 1860, German scientists Julius von Sachs and Wilhelm Knop prepared standardized inorganic salt solutions in order to determine the nutrients plants needed to survive. The term hydroponics was coined by Nebraska-born plant physiologist William Frederick Gericke in 1936.

According to a 2003 Food, Agriculture & Environment report by Professor Dimitrios Savvas of the Technological Educational Institute of Epirus in Greece, Gericke released numerous studies attempting to use hydroponics systems commercially. Although these experiments yielded disappointing results, the idea of hydroponics gained traction in the media and became explosively popular. This interest galvanized researchers to continue to experiment with hydroponics, and today these systems are extremely productive at the commercial scale.

Vegetable growing with LED Light Indoor farm, Agriculture Technology. Organic hydroponic Brassica chinensis

Why Use Hydroponics?

Like all indoor grow systems, hydroponic systems give the grower almost complete control over the cultivation process. Inclement weather, drought, flooding, animal and human intrusion, and most risks associated with cultivating outdoors are eliminated when the grow is moved inside. In addition to mitigating risks, indoor grows allow producers to control temperature, humidity, water, and nutrient flow in ways that optimize the cannabis growing cycle.

The reason many commercial grows are turning to hydroponics is specific: hydroponics systems do not use any soil. While there are many advantages to growing cannabis in soil, the risk of exposing cannabis to soil-loving pests and pathogens leads most growers to use pesticides. Pesticides are costly, environmentally hazardous, and can be dangerous for humans, so removing the need for them is a compelling reason to consider hydroponics.

In fact, a 2019 Environmental Science and Pollution Research International review by Professor Dimitrious-Panagiotis Manos of the School of the Pedagogical & Technological Education in Greece and Professor George Xydis of Aarhus University in Denmark argue that hydroponics system answer many of the problems presented by mass-urbanization and the subsequent degradation of the environment. Because the nutrients used to grow the plants are kept in an enclosed tank, they are not leached into soil and surrounding waterways. In fact, even when they are evaporated, they remain enclosed in an isolated system that will not threaten the macroenvironment.

The Risks of Using a Hydroponics System

Although soil elevates the risk of disease and pest infestation, it is also a living medium that, when properly maintained, can provide an environment rich with beneficial microbial life. For example, worms thrive in soil. They assist in the decomposition process by consuming dead organic material and the waste they leave behind leaves the soil rich with natural nutrients that will not burn the roots that absorb them. Once this microbiome is established, it sustains itself, removing the need for the intensive labor and maintenance required of less organic growing systems like hydroponics.

Moreover, hydroponics systems can be complex, requiring the use of many components. Each of these components must be properly maintained to avoid the growth of algae, mildew, mold, or nutrient build up—all threats to the productivity of the hydroponics grow, plant health, and harvest yield. The complexity of a hydroponics system is not just mechanical—growers will need to be savvy when it comes to pH and nutrient levels, which, when used in excess, can damage the plants.

Top 5 Hydroponic Systems

A closeup of marijuana roos grown in a clone machine. Marijuana plants are often grown from clones, instead of seeds. Cuttings are taken and rooted in foam discs while newly-formed roots dangle into nutrient-rich waters. These roots are pure white and form quickly; plants grown this way are ready to plant in a fraction of the time it takes to germinate and grow a seed to the same size.

There are many hydroponics systems out there, but not all of them are suitable for growing cannabis. Here are 5 we recommend.

Deep Water Culture System. This is one of the most popular methods of growing cannabis for a reason. In this system, cannabis roots are mostly submerged in a deep water tank infused with a nutrient solution. A pump makes bubbles that oxygenate the roots.

Bubbleponics. This very cute sounding hydroponics system produces some of the quickest yields of all hydroponic methods. It is just like a deep water culture system, except water is also pumped to the top of the roots. In these systems, the roots are absorbing nutrients from their end in the water tank and from their top in the soil-less medium they are placed in.

Nutrient Film Technique. This process involves dripping the nutrient solution onto cannabis that has been placed in a tilted container so that a “film” of nutrient-infused water flows from the first plant’s roots down to the bottom of the container, hitting each plant. The water is then drained into a tank and recycled.

Drip Irrigation System. This set up drips nutrient-infused water onto the roots from a top feed directly into the soil-less medium. The water can either be drained or recycled back into the reservoir from which the solution is pulled.

Aeroponics System. In an aeroponics setup, roots are suspended over water and continuously sprayed with a nutrient-dense mist. This is an excellent method for ensuring oxygenated roots.

You Need These Nutrients for Your Hydroponic System

Nutrient solutions are specifically made for the growing medium. That means growers should make sure they purchase nutrients that are designed for hydroponics systems. While organic nutrients work wonderfully in soil, hydroponic system users should opt for mineral-based nutrients that contain no organic matter. Finally, the nutrient solutions should contain the micronutrients that would typically be present in the soil to compensate for that loss.

The 3 most important macronutrients for any cannabis grow are nitrogen, phosphorous, and potassium.

Hydroponic nutrient solutions should also contain trace amounts of these micronutrients:

  • Magnesium
  • Calcium
  • Iron
  • Sulfur

Most water sources contain the following minerals, but extremely soft water may be lacking:

  • Boron
  • Colbalt
  • Copper
  • Manganese
  • Molybdenum
  • Zinc

If you are using very soft water, the above nutrients are a helpful addition to your hydroponic solution.

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