Benefits of Compost Tea – Garden Tips 2024

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Nobody questions the benefits of compost. So, how are compost teas different from compost? Quite simply, it’s a liquid version of the solid compost material we value so much to improve the soil in our gardens and improve plant growth. 

So, the benefits of compost tea are much the same as the benefits of regular compost. However, there are some very important safety measures that you will need to follow to avoid any unintended contamination from disease-causing pollutants. This is also important to ensure that compost tea has maximum benefit. 

What is compost tea?

Compost tea is a brew that many organic gardeners and farmers like to make. In essence, all they do is add small amounts of mature compost to water that hasn’t been heated. Then they leave it to steep or sit so that the water absorbs the rich compost. 

According to The University of Arizona College of Agriculture & Life Sciences Cooperative Extension, the process they use is an aerobic one. There are many ways to make it, largely depending on the scale of the process. 

The methods that home gardeners normally use involve placing compost in an enclosed space and maintaining it in an aerobic state. This encourages the microbial biodegradation of organic matter. 

This process also helps to degrade any potentially harmful pathogens that may be present in the raw organic matter. 

Rick Carr, from the Rodale Institute which trains farmers and educates consumers about organic farming, advises that we can apply compost tea as a soil drench or foliar spray. It also works well if growers incorporate it into an irrigation system. 

He talks about two diverging methods that we can use to prepare compost tea:

  1. Aerated
  2. Non-aerated

The aerated compost extracts need to be actively aerated with oxygen using a device like a blower or a bubbler. The other type is usually just stirred to mix in any solid materials that settle at the bottom of the mixture. 

How fast does compost tea work? 

Many people refer to compost tea as a vitamin boost for plants. Solid compost is more like a balanced and healthy diet. 

But one of the advantages is that researchers have found that compost tea works almost immediately. So, if plants are deficient in minerals like calcium and zinc, they will sort out the problem right away – or certainly within a couple of weeks. 

Benefits of compost tea

Compost is a great amendment for plant soil. It adds essential nutrients and microorganisms to the soil and helps to get rid of harmful organisms and possibly also plant diseases.  

It improves the structure of the soil, loosens the soil structure of clay, and helps sandy soil retain water and important nutrients. It also helps to prevent runoff, improves water retention, and makes it generally easier to work the soil. 

Even though compost is the most vital component of compost tea, there isn’t that much research to tell us how effective it is. To a large extent, the benefits of compost tea seem to depend on the compost used, and the method and temperature of brewing.

Evidence From Researchers at Harvard 

At Harvard University, researchers have been experimenting with compost tea as part of their organic landscaping and maintenance program. What they do is to “coax” the beneficial organisms from the compost and deposit them into an aerated water solution that also contains various food sources. 

They have found that beneficial bacteria doubles every half hour during the brewing process. They have also found that applications of the compost tea are great for trees and lawns that don’t need a high percentage of straight organic matter. 

Additionally, they have discovered that if compost tea is applied carefully it can speed up the process needed to balance the biology of the soil. But, it will take time to test and achieve effective compost teas. 

There is also evidence that compost tea can improve the ability of plants to manage disease-causing organisms.  

Evidence From Researchers at Arizona University 

The researchers at Arizona University focus on the compost tea benefits in arid environments where water for irrigation is often limited. They have found that organic farms that use compost tea use less water. 

The reason is that the compost tea reduces the need for plant growth. It also provides the soil and the plants with multiple benefits. 

Disadvantages of compost tea

It is commonly accepted that the main compost tea benefits rely on the quality of the compost used to make the tea. So, it stands to reason that the disadvantages lie largely in the inconsistency of products used to make it. 

The U.S. Department of Agriculture (USDA) has developed a compost tipsheet that includes the use of compost teas. While they don’t highlight disadvantages as such, they do emphasize the importance of meeting the guidelines that the National Organic Standards Board supplies. 

Even though these are not regulatory requirements, if you don’t follow them, your compost tea may not be of decent quality. 

For example, if you use compost that hasn’t maintained a temperature of at least 131 ℉ for three days, it’s likely to be substandard. If you start adding things to your compost tea, you can easily promote the growth of harmful organisms. 

If you make compost tea with additives and it isn’t tested or doesn’t meet water quality guidelines, then it isn’t safe to harvest crops or home-grown veggies until 60-120 days after you’ve applied your compost tea. 

Ultimately, the USDA doesn’t encourage people who are growing edible foods to spray them with compost tea. Their main concern is that it could inoculate food with e.coli and other harmful pathogens. 

How often should I use compost tea?

There are contradictory suggestions about how often to use compost tea. Some people say you can use it every day while others say limit it to every 14 to 30 days.  

But it’s not a good idea to use kind fertilizers more than once a week or once a month. 


Compost tea is a fertilizer that has lots of benefits. But there can be problems if you don’t follow important safety measures. 

It works fast and can improve soil structure and plant growth. Because of this, there is a lot of research on the go to find out more and establish safe guidelines for use. 

Probably the biggest problem relating to compost tea is that while the tea helps plant growth, the USDA has concerns about human health issues. 

If you decide to make and use compost tea, it’s prudent to follow the USDA guidelines, even though they aren’t mandatory.

t to follow the USDA guidelines, even though they aren’t mandatory.

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