What image comes to mind when you hear the term, “compost tea”? Well, compost tea is actually a nutrient-rich liquid that is created by steeping compost in water. It’s an excellent organic fertilizer and soil amendment that provides beneficial microbes, nutrients, and organic matter to plants. Here’s a basic recipe and method to make compost tea:

Materials Needed:

Vessel:

A 5-gallon bucket is enough to get started. However, depending on your requirements, more specialized brewers are available.

Compost:

High-quality, finished compost is best, so ensure it’s free from any contaminants or pathogens.

Tea Bag:

A cloth bag or pillowcase will work. However, I recommend using a paint strainer bag. This will allow plenty of room for microbes to be extracted from your compost, while preventing the larger material from contaminating the tea.

Water:

Use non-chlorinated water if possible. If you’re using tap water, let it sit out for 24 hours to allow chlorine to evaporate.

Aeration Equipment:

You’ll want an air pump that is powerful enough to distribute sufficient air to provide adequate oxygenation, as well as agitation of the suspended compost to distribute the microbes throughout the brewing vessel. Here is something similar to what I use.

You can connect multiple hoses to the provided splitter, and distribute them evenly around the brewing vessel for maximum efficiency. If you purchase and use the air stones that can work with this setup, keep in mind that you will want to adequately clean them between each brewing, and don’t forget to clean the tubing, as well. You can clean them the same way you clean the brewing vessel mentioned in the Tips section below.

Black Strap Molasses and Kelp Meal:

This provides a food source for beneficial microbes and helps increase microbial activity. People also add small amounts of alfalfa pellets/meal and azomite.

Steps to Make Compost Tea:

1. Prepare the Compost:

First, grab your “tea bag” and fill it with the compost and dry microbial food ingredients. Be sure you tie it off well so the compost stays inside the bag.

2. Fill the Container:

Next, fill a bucket or container with water. As mentioned, if using tap water, let it sit for 24 hours to dechlorinate.

3. Add Aeration:

If using a fish tank aerator, place the air stone into the bottom of the bucket. This will help oxygenate the water, promoting microbial growth. As previously mentioned, however, I recommend upgrading to a more powerful water pump as soon as you are able. Make sure it is one that can be submerged in water. If you have a specialized compost tea brewer, follow its specific instructions.

4. Add Compost Tea Bag:

Place the bag of compost into the water. Make sure it’s submerged. It is also important to suspend the bag in the water. If the compost bag rests at the bottom, the compost materials might settle and become compacted. This can hinder the extraction process, as well as promote anaerobic conditions.

5. Add Black Strap Molasses:

Add a small amount of black strap molasses (about 1-2 tablespoons per gallon of water). This feeds the microbes, helping them multiply more quickly.

6. Aerate and Brew:

Turn on the aerator or brewer and let the compost steep in the water for 24 to 72 hours (see below for guidelines on when to discontinue brewing). The bubbling action from the aerator will help extract beneficial microbes and nutrients from the compost into the water and incorporate aeration to properly oxygenate the brew.

7. Strain and Use:

After 24 to 72 hours, turn off the aerator or remove the compost tea bag. The compost is still full of beneficial microorganisms and nutrients and can be reused. Strain the liquid to remove any remaining solid particles.

Dilute the compost tea with water (usually a 1:4 to 1:10 ratio) depending on the strength and the type of plants you are feeding. Use the tea to water your plants, preferably within 4-6 hours of brewing for maximum benefit.

When to Stop Brewing:

Knowing when to stop brewing compost tea is essential to ensure that you’re extracting beneficial microbes and nutrients without promoting the growth of harmful pathogens. Several indicators can help you determine when to halt the brewing process:

Color and Odor:

The compost tea should have a dark, earthy color, similar to weak tea or diluted coffee. If it appears too light or clear, it might indicate that the extraction process hasn’t been thorough.

A pleasant, earthy odor is a good sign, indicating the presence of beneficial microbes. However, if the compost tea has a foul smell, resembling rotten or putrid odors, it may indicate the growth of harmful anaerobic bacteria, and you should stop brewing immediately.

Bubbling and Foam:

Initially, you’ll notice vigorous bubbling due to the aeration process. As the brewing progresses, the bubbling might decrease, and you might observe a foam forming on the surface. Once the foam starts to subside, it can be an indicator that the brewing process is nearing completion.

Duration of Brewing:

Typically, brewing compost tea for 24 to 48 hours is sufficient to extract beneficial microbes and nutrients. However, the exact duration can vary based on factors like temperature, aeration efficiency, and the desired strength of the compost tea. Monitoring the tea throughout the brewing process can help you determine the optimal brewing time.

Visual Inspection:

Inspect the compost bag and the water. If the compost materials appear to be thoroughly soaked and broken down, and the water has a rich, dark color, it’s a good indicator that the brewing process has been effective. Conversely, if the compost materials still seem dry or unbroken, you might consider extending the brewing time.

Tips:

• Always use the compost tea within 24-48 hours of brewing to ensure freshness and prevent harmful microbes from growing.
• Store unused portions in a cool, dark place.
• Regularly clean and sanitize your compost tea brewing equipment with water, a mild dish soap, and less than 1% bleach to prevent the growth of harmful pathogens.
• Adjust the brewing time based on temperature; warmer temperatures can lead to faster microbial growth, while cooler temperatures might require a longer brewing period.

By following these steps, you’ll be able to create a beneficial compost tea that can enhance soil health and promote plant growth in an organic and sustainable manner.

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If you enjoyed this post, you may want to read my posts about Thermophilic Composting and Vermicomposting.