What is compost tea? Why do I need it? How do I use it?

Those are questions every grower should ask before implementing compost tea.

Simply put, compost tea is a concentrated liquid blend of microbial populations that help your plants become vigorous and healthy producers, aid in moisture retention of the soil, and increase activity in the root zone so the plant can take up needed nutrients.

Let’s look at why it’s so important to successful growing. But if you just can’t wait, click here to find our recommendation for OMRI Listed Compost Tea that’s ready to use on purchase and available in multiple sizes.

What is the Difference Between Compost, Compost Extract, and Compost Tea?

Watch this video to see how we use compost tea in our raised beds.

Compost Tea allows transplants to thrive and easily adapt to their new soil without transplant shock.

Alright, we admit it. We’ve turned into soil nerds because of what we’ve learned. But we don’t mind. It helps us grow better food!

When I first heard the words “compost tea”, I thought it was essentially the same as compost, just liquefied. But they aren’t exactly the same. Of course, good organic compost is an important resource for the garden and we should use it. The organic matter and what it provides is very valuable.

Compost creates a good growing base and contains beneficial bacteria. Then we take it a step further and add other organic matter, such as chopped (cut) leaves. All the organic matter turns into food and carbon for the bacteria and other nutrients that plants need to grow and thrive.

A compost extract is the biological matter taken out of a good compost and brewed into liquid. It has a good amount of bacteria and beneficial biology. It can be used in soil drenches to help disperse those nutrients in the root zone.

Compost tea takes compost extract a little further. Instead of having only the nutrients from a compost extract, the active brewing combined with microbial food and catalysts multiply the bacterial population. With plenty of oxygen and food, there’s exponential growth of these microbes.

I like to call it “super concentrated” because there’s so many more microbes. 1 teaspoon of compost contains about 1 billion bacteria, but a good compost tea can contain about 4 billion bacteria in a teaspoon.

Wait, seriously? My head hurts trying to comprehend that one.

Anyway, this amazing liquid is particularly useful in foliar applications, but we also can use it in the soil.

Is Compost Tea Safe?

Some might worry that compost tea breeds pathogens or wrong bacteria we don’t want. But it’s important to keep in mind that the process of making compost tea is key to controlling what you get in the end. It starts with high quality compost so that the organic matter is diverse and healthy.

By keeping enough oxygen through consistent bubbling in the brew, it’s the perfect environment for all the microbes we want. Good microbes thrive with the amount of air coming to them in the brewer. Bad ones don’t.

So yes, using compost tea is safe if you start with a high quality compost and brew it properly.

Watch this video from The Soil Food Web School to learn more about brewing these mixtures.

What Will Compost Tea Do for My Plants?

You might think it won’t make much difference if you don’t use it, but applying compost tea can dramatically increase the health of your crops, help in disease and pest resistance, and give you a better yield when you harvest.

This is because when you introduce the tea and let the microbes do their job, you’re encouraging the soil food web to work properly. At our farm, we’re passionate about soil and soil health. We believe that a healthy soil is the foundation of organic agriculture and is where everything starts. Even if you’re only growing on a small scale for your family, you need good soil.

Plants are going to take everything they need from the soil they’re grown in. If the nutrients aren’t there, they can’t give you the end result you’re looking for.

How Do I Make Compost Tea?

It can be overwhelming to learn about how to brew your own compost tea. If you’re new to growing it can be especially daunting. However, if you decide you want to give it a try, there are many kits available now to make it easier.

One easy kit that’s great for many different size applications is made by TeaLAB. The brew kit comes with everything you need to get started and the company has other amendments and catalysts that are needed for brewing good compost tea. Plus, you can get support and questions answered by TeaLAB.

What If I Don’t Want to Make My Own Compost Tea?

If you prefer not to dive into something like brewing your own tea, you have another option. A great choice for organic and OMRI-listed compost tea is made by AgMent LLC based in Texas. You can buy 1 gallon or 5 gallons (and even more, but you likely don’t need even that much). Find QUE4BE – OMRI Listed (Note that “Micronutrients” means compost tea).

For a reasonable price and easy application when you don’t want to invest in making your own, this is a great option.

How Do I Apply Compost Tea and How Often?

Compost tea is liquid, so it needs to be sprayed on. We apply it to the raised beds in our greenhouse by using a 56 oz. hand sprayer from Home Depot. It’s easy to use and spreads the tea evenly over the soil. Our recommendation is 1 tbsp. per full sprayer (if that is the same size you’re using).

The rate of application is once every 3 months. You can’t overdo the tea in the sense that you can fertilizers. When you apply too much fertilizer, even organic ones, it can create problems for the plants. Not so with compost tea. It won’t hurt them to use a little more than strictly needed. However, you don’t need to go overboard with it. The plants only need so much. Why waste it?

Spread the tea solution over the plants and on the soil. It’s best if you don’t do this in extremely warm weather. The microbes are sensitive to too much heat when first applied.

Other Factors to Keep In Mind

While using compost tea is a great help to your garden (or even lawns), remember that it’s not the only thing that will make a difference for your crops. It’s not a cure-all. You need to keep your soil alive by not using any chemicals and maintaining the growth that’s started.

Avoid tilling your soil since this will destroy the microbes an the surrounding soil food web. Read our post about improving your garden soil to learn more.

Adding red wiggler composting worms and mulched leaves are good ways to enhance your soil.

Topping off raised beds with organic compost every year is always a good idea. If you grow directly in the ground, the same principles apply.

Learning More

We became fascinated with the soil food web after stumbling across the information through our own research. Wanting to understand how to make our crops healthier and prevent issues such as pests and diseases as much as possible, we found the book Teaming With Microbes on Amazon. In it, Jeff Lowenfels explains more about the soil food web and the relationship between plants and the soil materials.

Teaming With Bacteria is the newest book in the series (there are 4 total) helping you see how to implement the soil food web and make it work for you. Instead of relying on outside amendments and fertilizers (even organic ones), we want to make our soil as regenerative as possible. The less we have to do to it, the better. Encouraging its own processes to create the right balance for growth means better yields, fewer pests and diseases, and greater end results.

Dr. Elaine Ingham is a leading microbiologist and is responsible for much of the information about the soil food web we have today. Her website has videos and courses that are invaluable resources for us as we continue to learn more. Watch this video on her site for an easy to understand guide to how this works.

(Warning: you might become a soil biology nerd after reading and watching these)

We never stop learning and finding ways to improve our growing techniques.

Have you used compost tea? How did it turn out?