How Long Does Compost Tea Keep?

I’ve just brewed my first batch of compost tea and there’s more than I need for today. Can I keep it or should I put it on my lawn? I’ve heard compost tea has some sort of shelf-life but was hoping for some clarification.

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Dec 29, 2011
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Making Compost Tea For Later
by: Compost Junkie Dave

The jury is still out on this topic.

Years ago, it was thought that compost tea had no shelf-life. As soon as you brewed it, you had to use it. However, the research in the area of compost tea is blossoming and new discoveries about extending it’s shelf-like are emerging.

According to the most recent Compost Tea Brewing Manual (5th edition) by Dr. Elaine Ingham, the key to extending the life of your tea lies in the amount of available oxygen and food. That is, if you can’t use all of your compost tea immediately after brewing, keep aerating it and consider adding small amounts of food after 2-3 days. If you want to get technical, we recommended that you use a meter to monitor dissolved oxygen levels. You want to make sure these levels stay above 6ppm.

If the microorganisms in your compost tea have adequate oxygen and food, they will continue to survive. BUT, and that’s a big but, this can’t go on for long…

When initially making compost tea, you extract a highly diverse set of microorganisms from your source compost. As your brewing continues, these microorganisms increase in number, and also start to self-organize, which reduces their diversity. That is, the microbes start to adapt to their living conditions and those conditions start to favor certain microbes over others. That’s why the number and variety of microbes in a tea after 12 hours of brewing are not the same as the number and variety at 24, 48, and 72 hours. If you want to ensure you have a high number of diverse microbes in your tea we recommend using a lab-tested compost tea brewer.

Ensuring you have a diverse set of microorganisms in your compost tea becomes even more important if you plan to use it for foliar sprays (versus soil applications). Remember, we never really know what Mother Nature wants, so it’s best to provide her with as diverse a tea as possible and let her select what she needs at that moment in time.

To add to this topic, we learned something new about the shelf-life of compost tea recently. A friend sent us an article by a company out of Australia called Nutri-Tech Solutions (NTS). The article was titled “8 Essentials of Successful Microbe Brewing“. The author of the article claims that they have a product that can extend the shelf-life of compost tea by several weeks. How cool is that? To learn more, you can read the article here. Please note – We have not used this product, so we can’t vouch for the product benefits that NTS refers to in their article. Maybe we’ll get lucky and they’ll send us a sample or two…hint, hint.

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