Compost Tea Hydroponics – How to Make and Use Compost Tea

What are compost teas, and how exactly do they help in the process of organic horticulture? Well, the use of compost teas helps to enhance the microbial population in the soil, which is an essential biological component of organic horticulture. Besides, applying compost teas that have been exposed to air would greatly boost the general health of a plant. To illustrate this, it strengthens the plant’s resistance against pests and diseases, improves the absorbance rate of water and nutrients, as well as increasing the overall quality and quantity of production. Furthermore, using compost teas is a very affordable method as it allows people to even DIY at home. Putting it into simpler terms, the effect of compost teas on the soil is basically like how yogurt supports our digestive tracts and fortifies our immune system. With that, let us take the discussion on compost teas further in the following sections below. 

Using Tea as Plant Fertilizer

To provide some background on how fertilizers work, certain bacteria and fungi have the ability to break down insoluble minerals and matter into nutrients, increase the rate of absorption by sourcing beneficial nutrients and water to be dispatched to the roots. Also, bacteria are a form of food for organisms that helps to excrete even more fertilizer. Meanwhile, plants utilize certain microbes of their choice to change the pH levels accordingly so that they can defend against diseases causing microorganisms. This can work to a gardener’s benefit if they should need to adjust the pH of their soil.

Now, compost teas come into the play as it provides the soil with endless microbes which allows the plant to access essential nutrients. Using compost tea is highly advantageous with the reduced need for water and fertilizer, as well as having enhanced root growth and larger capacity in containing nutrients. 

Guide to Making Compost Tea

While brewing tea, the most important point to take note of is the type of compost used. On one hand, a high-quality compost can contain countless species of fungi, bacteria as well as nematodes, and protozoa. However, those of poor quality and immaturity could easily create opportunities for pathogenic bacteria and fungus to take over. 

Therefore, it is crucial for you to source a compost of good quality. To help our readers out, we would like to recommend vegetarian composts, simply because fertilizers derived from animals are often high in salt content and this increases the risk of having more pathogens.

The types of compost to be used usually depends on the type of plants you are growing as different plants naturally have different sets of requirements. For example, to achieve teas that are dominant in fungal content, compost high in wood chips or dried leaves is utilized. Whereas woody material is less essential in making a tea rich in bacteria, although it requires more application of sugar.

To brew an exceptional compost tea, the list of apparatus required is as outlined:

  • A bucket with a capacity of 5 gallons
  • An aquarium air pump 
  • An air stone

As this is just a general list, you are free to use more complex equipment when you become more proficient in brewing.

Steps for Making Compost Tea:

  1. Fill the bucket with water, let it rest overnight to allow the chlorine to evaporate entirely.
  2. Add either one cup of sugar cane or a quarter filled with unsulphured blackstrap molasses.
  3. Add a quarter cup filled with humic acid, seaweed extract and rock dust, although optional if you want a stronger vitamin and minerals filled solution.
  4. Use a cheesecloth, pantyhose, or an old tube sock to store one dry gallon of compost and let it sink in the bucket
  5. Utilize the air pump and air stone to expose the tea to oxygen for up to 18 to 24 hours.
  6. Detach the compost bag and the tea brewing is completed. 

In the process of brewing, microbes found in the compost undergo mass-replication as it feeds on the oxygen, sugar, humic acid, and minerals. As such, the tea is able to contain more microbes that the supported compost. 

After the brewing process, you should observe a pleasant sweet smell and the formation of foam. If you spot other results such as an unpleasant odor, do take immediate steps to properly clean the equipment as it is highly likely that they shelter harmful pathogens. 

Next, we would like to recommend for the aerobic compost tea to be used immediately after brewing completion because the shelf life is only 24 to 36 hours. To apply to both hydroponic and soil gardens, you can utilize the tea at its maximum strength. If not, you can also choose to have it diluted with non-chlorinated water, with a composition of one-tenth water to one part tea. Usually, the reason by diluting the compost tea is to enhance the coverage rate in a larger agricultural setting such as the greenhouses. Compost tea, both diluted and undiluted can be applied to the plants either as a drench or through a sprayer. If you prefer to use a sprayer, we suggest running the tea through a filter such as to prevent the nozzle from clogging up with compost particles. 

For application in hydroponic gardens, the advised ratio of compost tea to the reservoir is one or two quarts to 10 gallons. However, do take note that the ratio varies. At the same time, remember to maintain constant aeration. This is because a stagnant reservoir is a thriving environment for anaerobic bacteria as the oxygen levels go down. The addition of sugars is to act as a food source for the bacteria while the humic acid and seaweed extract provide a mineral solution. 

Another factor to consider is the use of a structure that helps to host the microbes and we recommend materials such as silica stone and biochar. Besides, in the absence of a media, with only Rockwool to make do, you can fill a bag of your selected material and set it in the reservoir. This should help the microbes to colonize it and proliferate. 


With that, we have reached the end of this article and you should be well-prepared to brew up a set of compost tea by yourself! Have fun, enjoy the process, and all the best!


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