Compost Tea Brewing

Compost Tea Brewing

What are the benefits of Compost Tea?

  • Tea-applied microbes consume and out-compete pathogens for plant surfaces and food resources
  • Reduces application rates of chemical pesticides, herbicides, and fertilizers.
  • Increases the number of organisms on and around the plant to compete with disease-causing organisms.
  • Occupies the space around the infection sites so even if the disease-causing organisms start to grow, they can’t penetrate into the plant’s tissues.
  • High nutritional value for plants and soil
  • Provides food to:
    • Feed beneficial organisms that protect plants (occupy infection sites)
    • Sustain and inoculate plants
    • Help extend root systems
    • Add nutrients (biology) to the soil
  • Increases water and nutrient retention
  • Increases microbial numbers and activities
  • Aids in the breakdown of toxins in the soil and on plants
  • It helps our watershed soil and water quality by improving soil structure, which in turn increases water infiltration/retention, oxygen diffusion, and microbial activity
  • Enhances organic taste of fruits and vegetables
  • Creates a safer place for people and animals by using a natural approach to plant and soil health rather than using chemicals
  • Impossible to over-apply to plants and soil because it is completely natural and organic
  • Since you are able to spray the tea directly on the leaves of the plants, this puts the organisms directly on the plant as opposed to adding compost to the soil around the plant.
  • Portability-You can spray at a rate of approximately 5 gallons per acre, depending on the biological numbers of your tea solution and 20 gallons per acre on soil drench.

What is compost tea?

Compost tea is an aerobic water solution that has extracted the microbe population from compost along with the nutrients. In simple terms, it is a concentrated liquid created by a process to increase the number of beneficial organisms as an organic approach to plant/soil care.

The concept behind compost tea is quite simple, though the actual process of making compost tea becomes scientific and very complex. The idea is that compost (full of beneficial microorganisms) is put into water and then nutrients or foods for the microorganisms is added to allow the bacteria and fungi to multiply rapidly. Air is sent through the water to keep the water oxygenated, as this favors the beneficial bacteria and fungi over the pathogens (ex.-e coli).

At the end of the brewing cycle, what you have is a concentrated liquid full of billions of microorganisms (bacteria, fungi, protozoa, nematodes) that can then be sprayed directly onto the leaf surface. This puts the “good” biology where the plant needs it to protect itself. It keeps the plant healthier and helps it to fight off potential diseases. The “good” biology occupies the infection sites on the leaf surface and is held there by simple sugars that the plant puts out (exidates) that work as a glue to keep the beneficial microorganisms thriving and protecting the plant.

Compost tea has been used by many people all over the world with mixed results. Part of the problem relating to studies on compost tea is that there is a high diversity in the quality of the compost tea produced in many of these studies. After all, if you don’t start with good compost, don’t add the proper amount of nutrients, or don’t keep the brew sufficiently aerated, you could be selected for the “pathogens” rather than the “beneficial,” and end up with compost tea that could potentially harm your plants. Much more likely is that the compost tea would be low in bacteria and fungi and have little more effect than putting water on your plant. At Keep It Simple, we take great care in our tea production and have tested all of our products thoroughly every step of the way. Our recipes have taken years to develop and we worked to maximize the biodiversity of our final tea product.

How to Apply Compost Tea 

After brewing the compost for 12 – 18 hours with the 5-gallon brewer or 24 hours for the larger brewers, the tea may be used as a foliar spray with a backpack sprayer on your plants or lawn. The backpack sprayer has a more useable nozzle that will not clog with the application. You may also apply with a watering can directly to the roots.

The application should be done in the morning or under cool conditions. It may be done in the rain when applied to the soil/lawn. When applied to leaves, it should be done during dry conditions. Because the microbes are active, they will attach themselves in 20 minutes.

The compost tea is most effective when used within 4 hours after the brewing process is completed. When the machine is turned off, the microbe population starts decreasing and you will want to use the tea when it has the highest microbe count. Four hours is the maximum time delay before application.

How to make Compost tea.

Brewing Instructions for the KIS 5-gallon Brewer

Once the brewer is assembled, fill your bucket with water just shy of 5 gallons, making sure the insert is in securely.

With dry hands, plug your motor in, put the lid on the bucket and start the motor.

Run for approximately 20 minutes if you have chlorine in your water.

Drop the “tea bag” and contents of the plastic bag into the bucket, again covering it with the lid.

Brew for at least 12 hours before use.

You may brew for up to 20-24 hours, although as you approach 24 hours, you will need to add more food and compost.


It is challenging to get high fungal numbers in your compost tea. The most important variable is your compost. If you don’t put high fungal biomass into your brewer at the start of your brew, there’s no way to get a high fungal count in your finished compost tea. Our fungal compost has extremely high levels of beneficial fungi and allows us to make a diverse, bacterial/fungal balanced tea with high nutrient cycling. Many commercial and homemade brewers make good bacterial teas, but without good fungal compost, foods, and aeration, you’ll never get high numbers of beneficial fungi onto your plants and into your soil


“The KIS brewers are extremely easy to set up and use, very easy to clean, and make great teas by extracting all the species of bacteria, fungi, protozoa, and nematodes present in the compost into the tea. Using the right resources, the KIS brewer can get fantastic fungal biomass growing in their tea maker. Using the KIS starter foods and compost, we have never seen the KIS brewer have a problem maintaining aeration. Even if “poor compost” has been used, where E.coli and other pathogens were in high numbers, these problem organisms have been dropped to less than detectable levels by the proper use of this machine.”

~Dr. Elaine Ingham, Soil Microbiologist, author the “The Compost Tea Brewing Manual, 5th ed.”
Corvallis, Oregon

“From the instant I got my KIS brewer, I knew it was going to be fun. The instructions were so simple that I set it up in about three minutes and turned it on before I went to bed. I used the tea in our greenhouse the very next morning (14 hours later instead of 12, but that was only because I slept in!). It was a fine looking brew with a great smell, good feel, and excellent color. I was quite sure my plants would appreciate it and I couldn’t wait until the snow melted and I could get our and use the KIS-made compost tea on our gardens and lawns.

Since that first day, I have made dozens of brews with the very same KIS brewer. And what a joy it is to use. The machine is so easy to assemble that I can decide to make tea one minute and be brewing it the next. And it is just as easy to disassemble for cleaning. The stopper is a real nice touch that allows the cleaning of the inside of the system. Cleaning the system takes me all of 30 seconds and that long only because I do such a good job.

Am I pleased with my KIS? Just try and take it away from me.

Thanks for this important machine. It will change the world. I know it has changed the way we garden here in Alaska.”

~Jeff Lowenfels of Garden Writers of America, author of “Teaming with Microbes, A Gardener’s Guide to the Soil Food Web.” Jeff is a member of the Garden Writers of America Hall of Fame, he is a leading proponent of gardening using the concepts of the soil food web. His life-long love of gardening has led him to write countless articles, host a popular gardening television show, and founding a successful program for soup kitchens called “Plant a Row for the Hungry” that is active in 48 states and has resulted in over 14 million meals fed to those in need.

“This was the best garden I’ve have had in years! I really noticed a difference with the health and taste of my vegetables and I didn’t have any disease problems. I love the smell and my garden loves it too!”

~Carin N. , Home Gardener Seattle, WA

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