What is Compost Tea? Plus, How to Make it.

Compost tea is a game changer for the garden. This guide will give you all the information about what compost tea is, and why you should brew it!

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What is compost tea?

To put it simply, compost tea is the liquid version of compost! It is exactly as it sounds. Imagine steeping tea in a mug…except that tea is compost…and you will NOT be drinking this tea! Compost tea contains beneficial microorganisms that make plants healthier. There are numerous ways to make compost tea, but the goal is to extract plant nutrients and microorganisms into a liquid. This liquid can then be applied on soil, on leaves, or even incorporated into irrigation systems.

There are two main different methods, when it comes to brewing tea: aerated or non-aerated. Aerated compost tea is actively aerated with oxygen using a bubbler or any other device that can force air into liquid. Alternatively the non-aerated compost tea method just occasionally mixes the tea to stir up the solids that have settled to the bottom.

Compost tea benefits

You may be asking yourself, why go through the effort of compost tea? Well plants need micro and macro-nutrients for proper growth. When the compost is placed in water the nutrients are released into the solution and are readily available after the tea is put on the plants. It is especially helpful if you do not already have organic compost available to you. It is a really fast way to get those nutrients into the garden!

Encourages microbial growth
Suppresses plant diseases
Promote plant growth
Eliminates the need for fertilizer
Fast way to get nutrients if you don’t have compost built up yet
Unlike compost, compost tea can be applied directly to plant leaves, where they compete for space with pathogens. This can help protect the leaves from attack!

How to make compost tea

There are a variety of different recipes to properly make compost tea. We only use and recommend a aerated method, and here’s how to do it!

Gather the brewing supplies

You’ll need a few supplies! You can find commercial products to help get you started or you can easily make your own system. All you need is a 5 or 55-gallon container (a bucket works great!), clear vinyl tubing, and an aquarium pump. The most important things, of course, are good quality compost, (non-chlorinated) water source, aeration, and some compost catalyst for good measure.

Fill your bucket with water

Make sure you are not using tap water, the chlorine can kill beneficial micro-organisms.

Add the catalyst

Dump the compost catalyst into the bucket. The catalyst can either be rock dust, liquid kelp, etc. This essentially wakes up the micro-organisms in the compost and encourages them to multiply.

Float your compost

Put the compost in a “sachet” in the bucket. A sachet? Think of the wire-mesh containers used in brewing the tea you drink. (If you don’t have a compost pile at home, bagged compost from your garden center is a fine alternative.) If you choose not to float your compost…you’ll simply need to strain the solids out later. The solid compost can still be spread in the garden later.

Pump it

Aerating is essential for the beneficial fungi and bacteria in the compost to start working. For 24 hours, let the air pump through the liquid. The finished product is a rich, frothy brew. The foam lets you know that the nutrients, bacteria, and fungi are going to do their work on your plants.

Things to consider

Remember that not all compost teas are equal. Different brews vary in nutrient content depending on what recipe you use.
Compost tea isn’t just about the nutrients, but ALSO the microorganisms. Some plants prefer different proportions. For example trees, shrubs, and perennials like compost tea recipes that are rich in fungi, where annual plants and vegetables prefer more bacteria than fungi.
Water should NOT BE CHLORINATED.
All compost tea needs a small amount of sugary tea like molasses, or maple syrup to help grow bacteria populations.

How to use compost tea on leaves

Having perfectly clean leaves isn’t necessarily a good thing. Leaves cambered with beneficial bacteria and fungi that are found in compost tea compete for space with the less desirable microbes. Applying compost the is an preventative step you can take to avoid pest invasion and plant diseases. This is essential in organic gardening! Rather than treating diseases with fungicides after they’ve already taken hold, apply compost tea at the beginning of the growing season!

Properly brewed tea shouldn’t burn the leaves. When applying your solution avoid doing it in the middle of the day when the sun is hottest. We recommend applying it in the beginning or at the end of the day. Use a watering can or a sprayer to generously apply the compost liquid to the top and bottom of the leaves.

How to use compost tea on roots

Adding compost tea directly to the plant soil is a great way to get organic fertilizer and beneficial microorganisms directly to the plant’s roots. Getting to tea to the roots is as simple as watering the plant at the base of the plant. The liquid will carry all of the good stuff around the roots.

Drenching with compost tea is a great way to quickly deliver organic fertilizer and beneficial organisms from compost to a plant’s root zone. Simply pour the tea mixture onto the soil in the area below the plant’s leaves (or under the “drip line”). The liquid tea will carry beneficial bacteria, fungi and other microorganisms down to the area around the roots.

Compost tea recipes

There are countless ways that compost tea can be brewed! The recipe we use most frequently is a combination of: compost, worm castings, alfalfa meal/pellets, liquid kelp, fish emulsion, azomite, and molasses! We brew ours in a 55-gallon drum because we have such a large growing space. It can however be brewed in smaller quantities! If you want THREE of our very favorite compost tea recipes and a handy chart that gives amounts needed if you are brewing a 5-gallon bucket or a 55-gallon drum, we wrote a FREE EBOOK for you! Grab your compost tea recipe e-book here.

Compost tea frequently asked questions

Which is better compost or compost Tea?

Both compost and compost tea have wonderful benefits for the garden. If I had to choose only one, of course I would choose a good quality compost. HOWEVER, there is benefit to using both. Compost cannot be directly added to the leaves like a tea. Infusing the roots with a liquid is a fast acting way to get your plants healthy! If you can I would suggest BOTH.

Does compost tea burn plants?

Only compost tea that is not brewed properly, and is too “hot.” It is sometime common to brew manure teas, which can definitely burn plants if it is is done improperly. Using a tried and true recipe like one from our FREE ebook will ensure the tea is safe for the leaves.

Do humans drink compost tea?

Aerated and non aerated compost tea can contain Salmonella and E. coli, both of which can prove to be deadly to humans. Do not drink compost tea!

What plants can I use compost tea on?

All plants can benefit from a shot of nutrients. Trees, shrubs, perennials, annual flowers and vegetables all do well when compost tea is applied.