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Secrets of Making Compost Tea

Brewing compost tea is easy. We’re going to teach you why making compost tea just makes sense, and how it will help you grow stronger, healthier plants by feeding your soil.

We were introduced to the concept of making compost tea about six years ago. Since then, we’ve talked to many experts, read a lot of books, and experimented with many different compost tea recipes. What we’ve found, is that we’re now able to grow greener lawns, more vibrant flowers, as well as higher quality vegetables…have you ever heard of brix?

In our opinion, making compost tea is a necessity if you want to get the most out of your gardening experiences.

Do you have a question about making compost tea?

If so, submit it using this form.

What is Compost Tea?

When we refer to compost tea we actually mean a product called Actively Aerated Compost Tea or AACT. In order to make sense of this term, we’d first like to tell you what AACT is not.

Actively Aerated Compost Tea is NOT…

Compost leachate – which is the liquid that comes from squeezing wet compost, or running water through compost, and allowing it to leach out. Compost leachate does not generate the massive number of beneficial microbes that are present in properly made AACT.

Compost extract – which is the mixture you get when you allow compost to steep in water for an extended period of time (e.g. 1-3 weeks). This extract will have bred more microbes than compost leachate; however, these microbes are predominantly anaerobic, which is not what you want to add to your garden. We’ll explain more about aerobic and anaerobic conditions below.

Manure tea – which is very similar to compost extract except that you allow a bag of manure, instead of compost, to steep in water for an extended period of time. This extract typically contains harmful pathogens, such as E.coli, because it has been allowed to go through anaerobic conditions. We do not recommend using manure teas in your garden.

Now that you know what AACT is not, we’ll tell you what it is…

Actively Aerated Compost Tea is the liquid product that is created by combining the following:

These ingredients are then placed in a container, such as a 5-gallon plastic bucket. An oxygen source (e.g. air pump and air tubes) is then placed into this bucket. Once in place, the air supply is turned on and oxygen is bubbled through the mixture for 12-72 hours (depending on the size of your brewer and desired level of microbial development). When completed, the air supply is removed, and the liquid is applied to your garden. Oftentimes, the liquid will need to be filtered prior to application, especially, if it is going to be applied through a sprayer.

Your GOAL When Making Compost Tea

The goal of brewing compost tea is to physically pull beneficial microbes from compost into a liquid medium. This is one of the main functions of the air bubbles (aside from providing a means of aeration). By agitating the compost, the air bubbles knock the microbes off into the water. Once in the liquid, you want to provide these microbes with the proper foods and conditions (e.g. adequate temperature and oxygen levels) to allow them to grow and reproduce. If you can do this successfully, you will have created an incredible organic compost tea, and it will enhance all of your gardening experiences.

Making Compost Tea

Aerobic vs. Anaerobic

One of the most critical things to consider, when making or buying high quality compost, is whether or not the compost has gone anaerobic (i.e. gone without oxygen) for an extended period of time. The exact same principle applies to making compost tea. You must make sure your compost tea does not go anaerobic. This means that there must always be enough oxygen present in your brewer to meet the needs of your microbes.

Visit our Compost Tea Maker page, to learn more about properly aerating and agitating your compost tea.

Aside from using a quality brewer, an easy way to tell if your brew has gone anaerobic is to smell it at frequent intervals (i.e. every couple hours). Your tea should always have a sweet, earthy odor. If your tea smells sour, or anything resembling vomit, it’s gone anaerobic and needs to be thrown out (not in your garden). The easiest way to ensure your brew doesn’t go anaerobic is to use high quality brewing supplies, and follow a compost tea recipe (see below).

Benefits of Compost Tea

  • increased pest resistance
  • increased disease resistance
  • increased yields in your vegetable garden
  • increased frost resistance
  • increased blossoms on your flowers
  • increased weed resistance
  • increased water holding capacity of your soil
  • increased breakdown of toxins in your soil
  • increased quality and taste of fruits and vegetables
  • 100% safe
  • 100% natural

Most importantly – compost tea is cheap and you get several of the benefits of applying compost to your garden, without the hassle of moving truckloads of soil around your yard.

Please note – compost tea is by no means a replacement for balancing the minerals in your soil or adding organic matter. If the minerals in your soils are not balanced and you’re lacking adequate organic matter, you will never fully realize the magic of compost tea.

Sun flower

Step by Step Instructions

The process of making compost tea is quite simple. However, we want to make sure you have all the guidance you need, so here are a list of step-by-step instructions in how to make compost tea. We will be using the K.I.S. 5-gallon brewing system. Please write us if you have any questions about your own brewing adventures.

Compost Tea Recipes

When you first start making compost tea, we suggest you follow a specific compost tea recipe. Once you’ve figured out the basics, you can start experimenting with other ingredients.

One of the first things you’ll notice, when looking at various compost tea recipes, is that they typically state whether the recipe will brew a tea that is fungal- or bacterial-dominated, or balanced. More specifically, there are certain compost tea ingredients that will help feed fungi, and others that will help feed bacteria. Depending on where you will be using your compost tea, you’ll want to ensure it contains the appropriate microbes. For instance, if you’re applying your tea to an annual flower garden, you’ll want to ensure your compost tea is bacterial-dominated; whereas, if you’re applying your tea to an established perennial garden including trees, you’ll want to ensure it has more fungi in it.

Update – March 2012

As of right now, we no longer recommend trying to brew one type of tea versus another. Instead, we recommend trying to brew as diverse a tea as possible and letting Nature select what She needs at that given time. The more diverse the set of microbes in your tea, the better chance you’re going to provide your soils with beneficial organisms.

Compost Tea Supplies

Making compost tea is becoming very popular. When we first started brewing, about six years ago, there were only a small handful of companies that were selling compost tea supplies. However, as it is with any growing market, when there is money to be made more companies will pop up to grab their share. Sadly, not all companies create products of equal quality, so here is a little advice before you buy

  1. Not all compost tea brewers are created equal. Some brewers don’t circulate the oxygen completely, which allows small pockets of harmful anaerobic microbes to grow.
  2. Not all compost tea pumps are created equal. Some pumps aren’t strong enough to provide enough oxygen to ensure your brew doesn’t go anaerobic. More often than not, these pumps also have a very short life span because they are overworked.
  3. Not all compost tea bags are created equal. Some bags are woven too tight and do not allow the larger microbes (e.g. fungi and nematodes) to be pulled into the solution.

The above list isn’t intended to scare you. It’s purpose is to help make you more aware of various things to consider when purchasing compost tea supplies.

To help remove some of the guesswork, and save you some money, we have partnered with one of the most reputable compost tea companies in the market – Keep It Simple. If you’re in the market for a brewer or other tea supplies, please visit our store

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Read Questions by Other Compost Junkies

Click below to see questions asked by other compost tea enthusiasts.

Hose End Sprayer for Applying Compost Tea to Lawn 
I would like to have a setup where I could take a couple gallons of fresh brewed compost tea and apply it to my lawn using a hose end sprayer. I have …

The Foam is Not the Measure of the Tea 
I was wondering if you would comment on the relationship between a “foamy” and a QUALITY compost tea? I remember reading that the foam is, for the most …

Temperature and Compost Tea 
I was wondering if there are parameters for the temperature of compost tea. I am doing a 5 gallon bucket outside Oregon and the temperature is between …

Where Do I Buy an Aeration Pump? 
Dave: I’m brewing my compost tea in a 5 gallon pail and have been using an aquarium pump with two air stones. I would like to buy a larger pump but do …

Homemade Compost Tea Bags 
Are all the ingredients in your tea recipes supposed to be in the compost tea bag or should they be left to float around in the liquid?

Building a Homemade Compost Tea Brewer 
I am going to build my own 20L/5-gallon version of a compost tea brewer. I’d like to replace my 44-gallon sealed plastic barrel setup, which I realize …

Using Compost Tea – Should I Dechlorinate My Water? 
When using compost tea, how do I apply it to my lawn and garden? I’d like to be able to hook it up to a hose, but I’m on city water and am concerned that …

Compost Tea and Biochar 
What is your experience with “charging” Biochar with compost tea? Does it work? Do you have any tips?

Compost tea in winter 
I want to apply compost tea to all of my planting beds (15 in all) over winter. I live in Southern California, zone 8b. I have very bad soil, high alkalinity. …

Compost Tea Book Recommendations 
I am starting a green business that would involve applying compost teas to residential landscapes. What books (if any) would you recommend to start researching …

Should You Use Surfactants When Spraying Compost Tea? 
The question I have for you has to do with spraying compost tea. Do you use a surfactant, or wetting agent, to help the tea stick to, and become absorbed …

Air Pump Went Out Overnight 
I had a batch of compost tea brewing last night and at some point, the power cord that (the air pump was plugged into) went kaput. The tea smells fine, …

Creating a Compost Inoculant with Specialized Bacterial Cultures  
I run an industrial composting facility in Ireland and we are very interested in producing a higher value product from our composting system. Unfortunately, …

How Long Before Compost Tea Goes Bad? 
How long is compost tea good for before it should not be used on plants?

Water Turns Brown Before Adding Ingredients To My Tea 
Is it normal for the water in my brewer to turn brown before I add all of my compost tea ingredients? Even before I turn on the motor it starts leaking …

How Long Does Compost Tea Keep? 
I’ve just brewed my first batch of compost tea and there’s more than I need for today. Can I keep it or should I put it on my lawn? I’ve heard compost …

Adding Mycorrhiza Fungi to Compost Tea 
I’m interested in adding mycorrhiza fungi to my compost tea. I’d like to apply this blend to my fruit trees. Would this be beneficial? I assume that if …

Bubble power 
I have a homemade compost tea brewer using a pail, pantyhose, and a marine bubbler, and seem to have some success. The bubble action isn’t close to the …

Everything Boiled Out of the Bucket? 
I made my first batch with my own recipe. 1 cup worm castings, 2TS seabird guano, 3TS Alfalfa Meal, 1TB greensand, glacial rock, 1ts Humic acid, myco, …

How Long does Compost Tea Last After Brewing? 
My plants are at different stages of growth and my watering times vary quite a bit. After brewing my compost tea for 48 hours, how long will it last? What …

Is it Possible to Keep Compost Tea for 6-12 Months? 
How can I store compost tea for a long time without damage? (6-12 month) Our Answer Monier, Please refer to the following post… How …

Are worm castings fungal dominated? 
If not, can I use worm castings to make worm tea, and use fungal food (such as soybean meal) to make a fungal dominated tea for fruit trees?

Using Bacterial Tea as a Starter for a New Batch of Tea 
I received some worm compost from a friend and made bacterial tea. I would like to make more tea but no longer have any more compost. Can I use some of …

Use of Compost Tea for Fruit Trees 
When making compost tea, what type (bacteria heavy or fungi heavy) do you recommend for the following types of fruit trees? : Pear, Cherry, Persimmon, …

Making Compost Tea with Vegetable Scraps 
I am going to school for horticulture. Last semester I made compost tea for my experiment in Greenhouse Crops. We used fresh vegetable remains and only …

Am I Making Compost Tea? 
From my chipper I put this mulch into a bath tub which is elevated above a 5 gal. bucket. Water is poured over the mulch and collected in the bucket under …