So you heard about worm tea and need to get clear what it is, whether it’s one of those big garden myths or wonders. Why you should or shouldn’t bother making any and how. 

Composting with worms has been gaining attention for a number of reasons. The more we learn about our damaged environment the more we need to know how to live more sustainably, regenerate soil to make sure we continue to be able to grow food that feeds us and doesn’t cost the earth and our health.

Earthworms play a vital role in this. Vermicompost (worm excrements) add vital enzymes, microorganisms and easily accessible plant nutrients to the soil. They do vitalize the soil. 

How does worm tea fit into this? Read on to find out! 

What Is Worm Tea?

Let’s start by what it’s not: It’s not the liquid that percolates through and out of a worm bin. This is called leachate. Although this liquid can be useful and contain plenty of soluble minerals and nutrients for plants, it is also likely to pick up any pathogens and phytotoxic (harmful to plants) anaerobic microbes (link) of the worm bin where organic matter is still decaying and rotting. 

However, leachate can have positive effects on germination and growth but it depends on what goes into the wormery. Test is best in case.

Worm tea on the other hand is an organic, high power liquid fertilizer, pesticide and soil enhancer all rolled into one. It is a product made from worm compost and castings, essentially the worm poop. 

When worm castings are soaked in rain water microbes, enzymes and nutrients move from the worm castings into the water and are therefore quickly and easily available for plants to use. 

Benefits of Worm Compost Tea

The quality and composition of worm compost extractions and tea depends what went into the worm composter, the composting conditions and therefore the quality of the vermicompost. 

High quality vermicompost from a mix of organic plant based material will provide

  • Fungi – especially useful for wooden plants like trees and shrubs
  • Aerobic bacteria especially beneficial for vegetables and flowers

However, this is not an either/or scenario. In fact, vermicompost will have fungi as well as aerobic bacteria and plants will use what they need. Soil and plants are self-regulating systems and worm tea will help boosting fertility gently. 

Worm Compost Tea Benefit #1: Regenerate and Boost Soil Fertility

Adding the brew to soil means adding lively microbial mass. This has multiple beneficial effects depending on what the soil needs. What isn’t needed will not do any harm.

One effect is the stimulation of minuscule flora populations and growth which in turn improve root growth of plants. One recommendation therefore is to inoculate seed soil with worm compost tea 1-2 weeks prior to sowing.

Liquid vermicast extractions and tea have also been used to regenerate and repopulate soil with microbes where agricultural or even industrial chemicals have left behind depleted and damaged soil landscapes.  

The tea is also packed with readily available macro and micro nutrients such as NPK and many more.

Worm Compost Tea Benefit #2: Pest Repellent and Improved Disease Resistance

First off, healthier plants are more resistant to pests and diseases. Providing plants with the nutrients they need and encourage diverse beneficial microbiological life in the soil are vital for their growth and high yields of vegetables and flowers.

This doesn’t mean pests and diseases can’t occur in an organic garden or in a greenhouse. However, worm compost tea will introduce certain microbial populations which can outcompete anaerobic and disease related organisms on roots and leaves. 

This way the immune system of plants is enhanced. 

Vermicompost castings contain a variety of enzymes, some of which are various forms of chitinase. Insects have a strong aversion against it as chitanase is involved in degrading their chitin shell.

Worm tea has been used to get rid of aphids, tomato cyst eelworms and root knot nematodes. 

When worm tea is applied to affected plants it will act on insects and disease affected areas directly but also boost the plants’ own immune system, making it stronger for future attacks. 

Worm Compost Tea Benefit #3: Germination, Growth and Yield Booster

Even though worm compost tea made from high quality worm castings often doesn’t necessarily contain high levels of nitrogen, potassium and phosphorus, commonly referred to as NPK levels. 

And yet, it has been shown over and over again to outperform chemical fertilisers with regards to growth and (even more important for sustainability) overall health, vitality of plants and soil.

Why and how?

One component of compost in general is humic acid. This compound plays an important part in making nutrients from the soil available to the plant as needed.

Vermicompost also slowly and steadily increases nitrogen levels in a form the plant can use. 

It is therefore fair to say that vermicasts and their tea and liquid extractions are life enhancers.

This makes vermicompost and tea very useful as a safe, harmless fertilizer across the garden, greenhouse or for flower pots on the window sill. 

How to Make Liquid Vermicompost Fertilizers

There are two ways to make worm tea. One involves simple soaking of vermicompost to obtain a worm compost extraction. The other is a proper, more involved (cold water) tea brew in order to boost the quantity of microbial activity in the liquid.

4 steps to Make a Liquid Vermicompost Extraction

You will need: 

  • Porous bag such as used burlap or paint strainer bag, panty hose
  • Chemical free water (rain water is good, let tap water from the mains sit for a day to remove chlorine which would otherwise kill off microbial life in the vermicompost
  • Vermicompost
    Note: Ratio Vermicompost in lbs /water in litre about 1:20, for example 1lbs compost in 20 ltr water


  1. Fill the porous bag with vermicompost (see above for amounts)
  2. Tie the top with a piece of string to be removed later
  3. Put the bag in the water
  4. Leave for 24-48 max (if you leave it longer, aerobic microbes will die off and decrease the benefits of the extract

How to Apply the Worm Compost Extraction

The liquid should be used shortly after extracting. The longer it sits the more it turns anaerobic.

Use to water any plants you want to boost.

It can also be filled in a spray bottle or mister and applied to foliage

Two recommendations from Sierra-worm compost:

  1. Spray trees and shrubs two weeks before bud break and then every other week at 1:5 part dilution.
  2. Mist or soak seeds prior to planting.

Add the ‘spent’ vermicompost to the garden soil or potted plants. It still has plenty of beneficial microorganisms to make the soil more fertile. 

How to Make Aerated Worm Compost Tea

Here is the main principle: Molasses (black treacle) and air are added to the water in which the vermicompost is seeping. The additional food and oxygen boosts the amount of microbes and bacteria to create an even more potent fertilizer compared to a worm compost extraction described above.

You will need:

Basic  Optional for better results
Worm castings
Porous bag to hold the worm castings
Chemical free water (rain or pond, let tap water sit for a couple of days to chlorine)
Aerator (aquarium pump for a 1 gallon liquid, larger pumps for bigger amounts of water – more technical info here)   Air stone for more and finer air bubbles
1-2 tablespoons of molasses (black treacle) as food source for bacteria and fungi Fish hydrolysate or alfafa meal to feed bacteria and fungi (more in depth info at

How to Use Aerated Worm Tea

Aerated worm compost tea full of aerobic bacteria and fungi needs to be used as soon as possible after switching off the pump as a decrease in oxygen will cause the micro biomass to decrease quickly. 

The brew can be applied using a watering can or spray bottle. 

Applying to the soil will boost microbial life and make nutrients easily available to plants. 

The tea can also be used on foliage as a safe pest repellent. Just make sure to apply it on leaves when there is little sunshine, so early or late hours is best or aim for an overcast day.