Organic Compost Teas: Brewing Beneficial Microorganisms

    Cannabis growers who are organic purists can approach fertilization and supplementation in a few different ways. Many growers choose to build-up their mediums with organic substances that will break down over time and give nutrition to the plants. These growers may or may not include liquid supplementation to their “nutrient rich” mediums. 

    Another tactic organic growers use is liquid fertilization. These growers rely on more inert mediums and provide most, if not all, the nutrition via liquid fertilization. Hydroponic growers fall into this category as the plant’s nutrition is completely provided by the nutrient solution. 

    In order for any organic grower of cannabis plants to achieve the largest yields and highest quality possible they must promote or supplement beneficial microorganisms. Beneficial microorganisms found in and around the plant’s root mass are responsible for the breaking down of organic matter into compounds absorbable by the plant. Whether growing in soil, soilless, or hydroponics an organic grower will need to find a way to maximize the beneficial microbes in the garden. Thanks to modern compost tea brewing methods there is a fast and easy way growers can continuously supply their organically grown plants with active beneficial microorganism. 

    Compost Tea

    The idea behind compost tea is fairly simple: soak organic compost in water, much like you would a tea bag in a cup, to obtain the soluble nutrients that are readily available for plant absorption. In most cases a straining bag or filter is used to hold the organic matter which makes for quick removal of the unwanted matter after the tea is done. The most popular “compost” products to brew tea from are worm castings, various manures including bat guano, and vegetable compost. The organic matter used will determine the nutrient make up of the finished tea. For example, a tea brewed from fish meal would be rich in nitrogen (and smell like death), while a tea brewed from high-phosphorus bat guano would be rich in phosphorus. This basic method of soaking organic matter in water to create liquid fertilizers has been around for many years. More recently though, with the addition of supplemental oxygen (usually provided by using a cheap aquarium pump), growers have taken compost teas to a whole new level. 

    Oxygenation of Compost Tea

    By adding small air bubbles to a classic compost tea a grower can not only acquire the water soluble nutrients from the organic matter but also breed a much larger population of beneficial microorganisms. Many of the beneficial microorganisms found in soil are aerobic creatures. This means they do well in oxygen-rich environments. The better oxygenated the environment, the faster these little creatures can reproduce (assuming there is an adequate food source). 

    Carbohydrates to Supercharge

    In addition to supplying oxygen directly to the brewing compost, growers looking for the largest possible populations of beneficial microorganisms should supplement a carbohydrate formula as well. Many of the microorganisms found around a plant’s roots have a symbiotic relationship with the plant itself. The beneficial microorganisms will actually feed off carbohydrates secreted by the plant’s roots and, in turn, create enzymes which aid in the breaking down and absorption of nutrients. The beneficial microbes will also use the carbohydrates secreted by the plant’s roots as food to grow and reproduce. By supplementing a carbohydrate formula into the tea, cannabis growers can facilitate the natural processes that happen in and around a plant’s root zone. This includes the growth and reproduction of many beneficial microorganisms. Compost teas supplemented with carbohydrates create even larger populations of beneficial microorganisms than compost teas that use oxygenation alone. 

    Additional Filters for Hydroponics

    Organic purists who still want to enjoy the benefits of hydroponic growing may do so with the use of microbial-rich compost teas. Unfortunately, rich compost teas may be a nuisance for the hydroponic grower because emitters and pumps may easily be clogged and, frankly, make a mess out of everything. Hydroponic growers looking to gain the benefits of compost teas but lose the hassles should implement a triple filtration process. 

    Filter 1 (Initial Brewing Filter)

    First, filter the organic material in the brewer. As previously mentioned, most gardeners use a screen bag or some other filtration to remove the bulk of the organic material from the tea upon completion. This filter should be used by all gardeners whether they grow in hydroponic systems or soil. After the initial filtering, soil growers can go ahead and apply the tea. 

    Filter 2 (Secondary Brewing Filter)

    A smaller screened filter should be used for the secondary brewing filter. Some of the extraction bags sold at hydroponic retailers can actually be used as a secondary compost filter bag. Organic purists can also implement a natural filter for the secondary filter. I have seen some impressive natural filters built from five gallon buckets and gravel. If used regularly, a natural filter will eventually create its own micro-ecosystem complete with its own beneficial microorganisms. 

    Filter 3 (Equipment Filters)

    Last, but not least, organic hydroponic growers using compost teas should use filters on all pumps being used in the hydroponic system. Most submersible pumps come equipped with their own filter. In addition to that filter, a pump filter bag can be used to make certain any remaining sediment in the compost tea remains in the reservoir and does not affect sprayers, emitters, or the plant’s roots. 

    By oxygenating the compost teas and supplementing with carbohydrates, cannabis cultivators can produce the most microbial-rich teas possible. With the proper filtration organic hydroponic growers can enjoy the speed and convenience of hydroponics while incorporating organics for heightened quality and flavor. 

    Eric Hopper is the Editor in Chief for NUGL Media. He can be contacted at


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