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 five 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?

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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:

• high quality compost
• microbial foods (e.g. molasses, kelp, fish emulsions)
• dechlorinated water

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. 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. 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.

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). 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. If not...

You're going to start breeding harmful pathogens, like E.coli.

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 almost all of the benefits of applying compost to your garden, without the hassle of moving truckloads of soil around your yard.

Up here in Ontario, we grow a lot of tomatoes; however, they're often infected with blight. That was until...we started making compost tea and applying it to their foliage and soil. The tomatoes that received this added TLC throughout the season, were much more resistant to the disease; some of them resisted it all together.

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.

To learn more about compost tea recipes, including when and where to use various types of teas, please click here.

Compost Tea Supplies

Making compost tea is becoming very popular. When we first started brewing, about five 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. Other pumps are too strong and actually kill the microbes in your brew.
3. Not all compost tea bags are created equal. Some bags are woven far 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 selected several reputable companies who provide high quality compost tea supplies.

Microscopy and Compost Tea Analysis

In order to do justice to the world of compost tea, we must delve into the world of microscopy. We are referring to the use of microscopes to analyze and assess the organisms in your compost tea.

Using a microscope is the absolute best tool to assess the quality of your tea, so much so, that entire businesses have been built around this very thing. For example, Soil Food Web.

We've chosen not to introduce this topic to you until now for two reasons. The first is that we haven't taken adequate microscopy training yet, and second, most gardeners don't need to go this far "down the rabbit hole" to experience the benefits of compost tea. From our interactions with our tribe members, it appears that most of you are interested in using compost tea on a small scale, you're comfortable putting your trust in a quality compost tea brewer, and would like to leave the "details" up to the experts.

However, we noticed a couple complaints creeping up on the web about us not mentioning microscopy when discussing making compost tea, so we wanted to add this section to our site. If you're REALLY keen on learning more about the science of making compost tea and microscopy, we recommend you visit one of the gurus in this field - Tim Wilson at Microbe Organics. We also suggest you get in touch with Soil Food Web and consider taking a microscopy course...maybe we'll end up sitting beside one another in class.

Five Free e-booklets

Interested in learning more about compost and compost tea?

What if we told you you're just one click away from being able to download five free compost e-booklets?

All you have to do is click on the Compost Tea and Vegetable Gardening booklet to the right and read our Free Goodies page.

Got a Question About Making Compost Tea?

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Read Questions by Other Compost Junkies

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