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How Long Does Compost Tea Last? (And how to Make it Last Longer)

Most gardeners are very familiar with all the benefits compost tea can bring to their gardens.

This is especially true among those who like to employ the DIY approach when tending to their plants.

Made by steeping the compost in water, this high-nutrient and organic-rich liquid decreases the use of water, deters pests, and reduces the reliance on chemical additives to ensure the healthy growth of plants.

One of the major advantages of compost tea is that it’s relatively easy to make and use in your garden.

However, you should be aware that it’s basically a living thing filled with micro biotic bacteria.

This means that it has limited time of use, as the longer you wait to use it, the more microbial activity will decrease.

Still, as many gardeners make more of it than they use right away, it’s important to know how long does compost tea last.

So let’s find out together!

How Long Does Compost Tea Last?

Compost tea has a fairly short shelf-life, which can span from only 24 hours to a couple of days, depending on several factors.

If you can, it’s best that you use the compost tea as soon as the brewing process is finished, at the height of microbial activity.

This way, you’ll maximize its usefulness for your plants, due to the highest amount of beneficial aerobic bacteria and fungi living in the liquid during the first 24 hours after the brewing.

After that time, unless you additionally aerate the compost tea, the good aerobic microbes will become less effective, go dormant, or even die.

This happens because aerobic bacteria, which are the most common in DIY-made compost tea, quickly use up the available oxygen in the water, creating an unlivable environment for themselves.

So, the longer you leave the compost tea, the more microbial activity will decrease, making it less valuable.

How to Make Compost Tea Last Longer?

Compost tea making by Stefano Lubiana (CC BY 2.0)

In some cases, you won’t be able to use compost tea right away, for various reasons.

Fortunately, there are ways to extend its shelf-life, so you have more time to use compost tea before it goes bad.

The key reason why the compost tea doesn’t last long is the lack of oxygen, which is the necessary prerequisite for microbe development.

If you can provide them with enough oxygen and ensure that the oxygen levels in the compost tea stay high, the microbes will continue to thrive and be active.

So, the best way to keep your compost tea good for a longer period is to aerate it.

The easiest way to do this is by regularly stirring the compost tea. However, this will only slightly raise the level of oxygen.

The more efficient, but also the more expensive, way is to add an aerating device to your compost tea setup.

How to Store Compost Tea?

Proper storage of compost tea is another way you can make it last a bit longer.

Keeping it in a tightly sealed and light-proofed (opaque) container can potentially extend the usability of the compost tea for a couple of days.

However, when storing the aerobic compost tea this way, you’ll need to provide aeration.

This can be done by using an aquarium pump  or a bubbler stone.

Adding these aeration devices to your composting setup will provide continuous aeration, and allow microbes to stay alive and lively, creating a favorable environment for their development.

By making the compost tea last longer, you will be able to schedule your plant maintenance easier and provide better conditions for their healthy growth.

How to Tell that the Compost Tea has Gone Bad?

Sometimes, you may lose the track of how long the compost tea has been stored.

While it’s very likely that it has gone bad, it’s best that you learn how to identify if it’s still usable or if it’s just a waste.

The easiest method to establish if your compost tea has gone off is to simply smell it.

In general, the compost tea will not have an unpleasant odor and will likely have an earthy smell similar to traditional compost or soil.

However, if due to the lack of oxygen, the aerobic bacteria in the compost ta have been replaced by non-aerobic varieties, the smell will change.

Anaerobic compost tea will commonly have a foul odor, mainly because it will become a source of methane and other greenhouse gases that emit an unpleasant smell that you will sense if you get closer or handle it.

Why the Compost Tea Shouldn’t be Kept for Long?

As I already explained, the longer you keep the compost tea, the lower the oxygen levels will be, decreasing the active microbe population.

However, besides decreasing the number of microbes, this also reduces their diversity.

In the process of making the compost tea, a highly diverse set of microorganisms is extracted from the original compost.

As the compost tea brews, the number of microbes initially increases, which is of course beneficial.

However, if you wait longer microbes will adapt to the environment in the compost tea, and the living conditions will favor certain types of microbes over others, decreasing their diversity.

Having a high variety of microbial species in your compost tea will increase the chances that its use will be beneficial for the plants.

The diverse set of microbes will allow the plants to select what they need the most at a particular moment.

Can Non-Aerobic (Anaerobic) Compost Tea Last Longer than Aerobic?

Anaerobic tea will typically last longer than the aerobic type, mainly due to the fact that anaerobic microorganisms don’t need oxygen in the liquid as most of these microbes are either dead or dormant.

This is why when the level of oxygen decreases, aerobic microbes are replaced with their anaerobic counterparts.

The main reason for brewing anaerobic compost tea is for the nutrients, not the aerobic activity.

Which Type of Compost Tea to Use?

Still, even though the anaerobic compost tea can be kept longer, its application is more limited.

Aerobic compost tea brews work to increase the beneficial microbial population on plants and soil and do it much faster than the non-aerobic variants.

Additionally, anaerobic compost tea may contain the wrong variants of nutrients and microbes.

Because of this, it should be used only as a soil drench and applied sparingly and heavily diluted.

On the other hand, aerobic tea can be used every time you water your plants and works as both foliar and soil drench.

Conclusion

Compost tea is one of the best options when it comes to providing your plants with nutrient-rich food to ensure their healthy growth.

It’s very simple to prepare and you can make it with materials and ingredients that you already have in your household.

However, for compost tea to maintain its beneficial properties, it shouldn’t be kept for too long. Most likely, it will go bad rather quickly after it has finished brewing.

So, it’s best to apply it in your garden immediately after the end of the brewing process, or at least within 24 hours.

This will minimize the risk of the development of dangerous variants of bacteria and ensure that the beneficial microbes that you have worked to develop are still active.

Under certain circumstances, compost tea may last longer, but make sure to monitor it and discard it as soon as it starts to smell bad.

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