In the gardening world, worm tea is heralded as the fix-all solution to plant and soil health. As much as I, as a full time worm farmer, would love for it to be that simple, it’s simply not.
Let’s bust some myths, learn more about worms and soil microbiology, and have some fun along the way!
What is Worm Tea?
Worm Tea is a liquid “fertilizer” made using worm castings.
It is a mix of water, and all of the goodness of worm castings such as:
- Water-soluble nutrients
- Humic & fulvic acids (liquid forms of organic matter)
- Plant growth hormones
- Beneficial bacteria, fungi, protozoa, and nematodes
- Enzymes and metabolites worms naturally produce
The Problem with Worm Tea – Does it Really Work?
In my definition of worm tea, I emphasize goodness because it should be implied that the worm tea is fit for “plant/soil consumption.” Worm tea is a highly populated culture of microorganisms – a living product. It can go bad, or be made bad.
Quick – think of your favorite food! I’m guessing when you imagined it, it was fit for human consumption and wasn’t moldy/rotten. That’s because we have laws in place to provide a standard of quality on a given food item, and you don’t have to specify that you want to buy an “edible” pasta vs. a month old pasta when buying some food. It has some standard of quality assumed without specification.
Unfortunately, a standard of quality has not been established for worm tea. When someone refers to worm tea, it could be a 3 star Michelin dish, or it might be a burrito made with spoiled rice – people are still calling it “worm tea.”
I believe this is where a lot of the differences of opinion stem from, and why people may report huge results from worm tea, while others might report no effect or even a negative effect on their plants, saying that worm tea is a fake.
A bad worm tea definitely does not “work,” but let’s look at if a good worm tea does!
The Benefits of Worm Tea
The benefits of a well made worm tea are almost unbelievable.
- Beet farms have increased their yield by 42% and improved sugar content using just 7 gallons of compost tea per acre.
- Potato farms have reduced pest pressure and boosted yield by 42% with 30 gallons per acre.
- Pastures have seen 50% higher protein levels in grasses and a 25% increase in cattle weight using 20 gallons per acre.
So…How is this possible?
So… how is this possible?
These results come from experts. The figures above come from case studies by Todd Harrington of organiclandcare.com, who has spent decades mastering how to cultivate a diverse, active microbiome in compost and worm teas — and how to apply it successfully in the field. Other growers have reported similarly impressive outcomes.
Of course, the average home gardener won’t see results quite this dramatic. But it’s still worth understanding why worm tea works, because anyone can capture some of this magic at home.
It’s NOT the Nutrients – It’s the Microorganisms
In these large-scale trials, the worm tea was diluted so heavily that the nutritional content alone was negligible. If you’re only thinking about NPK, trace minerals, or chemistry, you’ll miss the real benefit.
The magic is in the biology.
In every tiny droplet of diluted worm tea, there might be a single bacterium, a strand of fungal hyphae, or one small protozoan.
And from that:
- One bacterium becomes two
- Two protozoa become four
- And so on, multiplying exponentially
That tiny, almost invisible inoculation eventually becomes billions, trillions, even quadrillions of organisms in the soil once they establish themselves.
These microorganisms are responsible for the true functions of healthy soil: nutrient cycling, improving structure, increasing water retention, helping suppress pests, and building organic matter over time.
Now it makes sense why some people brush worm tea off as a fake — while others swear it’s a fix-all solution. It all comes down to the biology at work beneath the surface.
Worm Tea vs Worm Extract
Before we go any further, I want to introduce an easier alternative to worm tea — one that’s more stable, quicker to make, and still delivers most of the same benefits.
Worm tea gets a lot of attention, but worm extract is often the simpler, more foolproof option. It has most of the benefits, without the fuss, and it’s almost impossible to get wrong.
Worm extract is essentially worm tea without the added food source and without the need for aeration.
You’ll see the full method in the next section, but here’s the short version:
Simply place the worm castings into a tea bag or mesh bag, submerge it in water, and gently massage the bag so the water flows through the castings. This releases all the “worm goodness” – the biology, enzymes, and soluble nutrients – into the water.
If you want it stronger, just empty out the bag and add fresh castings.
Keep going until the water becomes a rich, earthy colour. The beauty is:
- you can’t add too many castings
- you can’t add too few
- and you can’t make it too concentrated or too diluted for your plants
It’s truly that simple, and honestly, it’s the best place to start before diving into full-blown worm tea.
But because worm tea tends to attract more excitement (and more questions!), and because the two are similar enough to explain together, that’s where we’ll focus next.
How to Make (Good) Worm Tea
What You’ll Need:
1. The Worm Castings
Worm Tea starts with good worm castings. Red wigglers are the easiest species to use. You can buy red wigglers to produce your own worm castings, or skip the wait and get worm castings from someone close to you. You should prioritize worm castings that have been tested for a healthy and active microbiome.
2. A Brewing Container
On a small scale a 5 gallon bucket will work, but anything larger you’ll want to get a conical bottom tank.
3. A Tea Bag
400 micron mesh bags are best
4. An Air Pump
Do not use air stones – they are difficult to clean and biofilm can build up inside of them harboring harmful microorganisms that can affect the quality of your teas. Options like the bubble snake are good for 5 gallon buckets, or use a regenerative pump for larger ones.
5 Food to stimulate microbial growth
Molasses is not a great option! Molasses is a very simple sugar, which means it will breakdown by bacteria extremely rapidly. This rapid growth can deplete the oxygen in the tea even with a bubbler, driving the tea anaerobic and bad.
Besides that, we don’t really need to focus on growing more bacteria, there will already be plenty in the tea without molasses. The organism we should try to focus on is more fungi. Choose other foods, like fish hydrolysate or soluble kelp, which will help develop fungal growth and a more microbially balanced worm tea.
Quick Fact: The liquid that falls out the bottom of the worm bin is NOT worm tea, but is called “leachate.” It is not recommended to apply to plants as the liquid came from a waterlogged worm compost – deprived of oxygen. Without oxygen, harmful microorganisms may be abundant in the leachate.”
Making Worm Tea Step by Step
Step 1: Fill Container with Non Chlorinated Water
I shouldn’t recommend using chlorinated water, but I have used chlorinated water and ended up with great tea. But, removing chlorine is the safest way to do it and its pretty easy to do it – just leave water outside for 24 hours (ideally in the sun) and most chlorine should gas off.
Step 2: Place Air Pump into water
Set your air pump above the water line.
This way, if the power cuts out, water won’t siphon back into the pump.
Step 3: Add Worm Castings to a Tea Bag
Scoop your worm castings into a mesh bag or “tea bag” and suspend it in the water.
You can’t really overdo the castings, but 1 pound per 5 gallons is a great starting point.
Step 4: Add Food for the Microbes
Less is more here!
You only need a tiny amount to wake up the microbes. I’ve used as little as 1 mL of fish hydrolysate per gallon (roughly 1 part food to 4,000 parts water) and seen excellent microbial activity.
Make a note of how much you used so you can adjust next time if needed.
Step 5: Aerate and Wait
Let the tea brew for at least 12 hours, but aim to use it before 36 hours for the best microbial activity.
You’re looking for aeration that resembles a gentle rolling boil.
It should be strong enough to push microbes off the worm castings and keep the water well oxygenated, but not so intense that it splashes out of the bucket or becomes harsh on the organisms.
The warmer the temperature, the faster the microorganisms multiply – which means shorter brew times. Cooler conditions may need a little longer.
Make a note of how long you brewed the tea and what the temperature was so you can fine-tune your process next time.
This product has an excellent video showing good aeration. The product itself has everything you need to start a 5 gallon tea brewer (besides the bucket and worm castings)
Step 6: Use Immediately
Once the tea is removed from oxygen, its countdown to “expiring” begins. For best results use it right away.
For applications at home; you can dilute it, or not dilute it, as much as you’d like. It’s pretty easy to make another batch of tea, so I’d favor just making more tea over diluting it too much – whatever is easiest for you!
Assessing Worm Tea Quality
- Using a microscope to examine the microbial profile.
- This is the best/most scientific way to ensure you have a high quality tea (and not just an OK tea), but this is a whole other topic that you might see covered on potager project later!
- A good earthy smell similar to a forest is best. Foul smells are bad signs.
- Besides lingering smells from the food source – fish hydrolysate is inherently a bit stinky
- A rich brown color
- If you have a pH tester handy, a 6-7 pH is best, and wild pH readings may indicate a bad tea.
You might not have a microscope to do a microbial analysis on the tea, but fortunately the best test possible is available to anyone – testing its quality by actually testing it on plants, which is what its all about anyway!
Record how you made the tea, which food, amount of food, how long it was brewed for at what temperature, which castings you used, how much you applied on the plants, etc.
Choose some plants to be the treatment group and other plants to be the control. For best results, make sure the treatment group and control group are as similar as possible and experience as similar conditions as each other – besides the worm tea application of course.
Treat the treatment group with worm tea and record any changes you observe compared to the control group.
How to Use Worm Tea
Using worm tea is quite simple – if you made a good worm tea you can’t do it wrong! It won’t burn plants and doesn’t need to be diluted. Spray it on the plants as a foliar spray (which is technically the way you’re “supposed” to do it), use it to water plants, drench transplants, or anything you can imagine really – just don’t drink it yourself!
Storing Worm Tea
Worm Tea is a living product – it’s not really meant to be stored, which is why I don’t recommend buying any worm tea that hasn’t been made for you fresh. If you need to store it just for 12 hours or so, place it in a cool area out of the sun, and don’t “bottle” it – keep it in contact with oxygen. If practical, shaking it/stirring it to reintroduce air can help too.
Worm Tea FAQs & Myths Busted
1. What is Worm Tea, Exactly?
Is worm tea worm pee?
No — worms don’t pee. Worm tea is made from worm castings, not worm urine.
Is worm tea the same as leachate?
No. Leachate is the liquid that drains out of a wet worm bin. It’s usually anaerobic and can contain harmful pathogens, so it’s not recommended for plants.
2. How to Make Worm Tea (and Common Mistakes)
Do I need an air pump to make worm tea?
Yes you do need an air pump to make worm tea. Without aeration, the tea quickly becomes anaerobic.If you’re not using a pump, make worm extract instead — it’s safer and more stable.
What food should I add to worm tea?
When considering what food to add to worm tea, avoid molasses — it can cause harmful bacterial blooms. Instead, use fish hydrolysate or soluble kelp in very small amounts.
Are air stones good for worm tea?
No — air stones are not good for worm tea. Air stones grow biofilm inside them, which can’t be cleaned and will contaminate future teas.
How long should worm tea brew?
Worm tea should brew for 12–36 hours, depending on temperature. Warmer conditions = shorter brew time.
How do I know if my worm tea went bad?
It will smell rotten or have an extreme pH. Healthy worm tea smells earthy and fresh.
3. Using Worm Tea in the Garden
Does worm tea need to be diluted?
No — worm tea does not need to be diluted; it can be used straight or diluted. Either is fine for home gardeners.
How often should I apply worm tea?
You can apply worm tea as often as you like. A few times per growing season is a great baseline.
Can worm tea burn plants?
No — worm tea won’t burn your plants.
Is worm tea safe for all plants?
Most fruit, veggie, and ornamental plants love it. Carnivorous or nutrient-sensitive plants won’t benefit.
Can worm tea revive dying plants?
Worm tea can help revive dying plants, especially if poor soil biology is part of the problem.
Should I use worm tea as a foliar spray or soil drench?
You should use worm tea as a foliar spray and as a soil drench. Plants have ecosystems above and below the soil, therefore, foliar + soil applications deliver the best results.
Does worm tea attract pests?
A good worm tea won’t attract pests. In fact, teas made from chitin-rich materials can help reduce pest pressure.
4. What Does Worm Tea Actually Do?
What does worm tea do for plants?
Worm tea provides beneficial microbes, enzymes, and growth hormones that support healthier soil and plant growth.
How fast will I see results from worm tea?
You will often see results from worm tea within 24 hours – plants will look perkier! Long-term benefits build gradually.
Can worm tea replace fertiliser completely?
For many gardens, yes, worm tea can replace fertiliser completely! It naturally improves nutrient cycling. Heavy feeders may still need additional amendments.
Is worm tea better than compost tea?
Often, yes. Worm castings tend to contain a richer and more stable microbial community than compost tea.
Worm tea vs synthetic fertiliser — which is better?
Synthetic fertilisers give quick nutrients but don’t improve soil structure or biology. Worm tea boosts soil health, not salt-based nutrients.
5. Storing, Buying, and Selling Worm Tea
Can I store worm tea?
You can only store worm tea for 12–24 hours, and even then the quality declines fast. Fresh is always best.
Should I buy bottled worm tea?
No you shouldn’t buy bottled worm tea — bottled tea is usually inactive or dead. You won’t get the microbial benefits.
Can I sell worm tea legally?
Regulations vary — check your local laws before selling or distributing worm tea.
6. Extra Myths & Troubleshooting
Is foam or bubbles a sign of good worm tea?
No, foams or bubbles are not a sign of good or bad worm tea. Foam has no correlation with tea quality.
Why did my worm tea smell bad?
Too much food or not enough aeration causes the tea to go anaerobic and smell bad.
Can worm tea go mouldy?
Yes, worm tea can go mouldy. Once oxygen is removed, it can spoil or grow mould.
Is leachate harmful to plants?
Leachate can be harmful to plants. It’s generally best avoided unless properly treated
About the Author
Scott Kent is a worm and microbe farmer with a passion for helping gardeners build healthier soil. What began in 2014 with a single worm bin quickly grew into a full-time career, and today Scott runs Hungry Worms, one of the largest vermiculture operations in the USA.
His studies with the Soil Food Web deepened his understanding of soil microorganisms and the powerful role they play in plant health. Scott’s mission is to share the benefits of worm castings and soil biology, making it easier for gardeners to grow thriving plants, naturally.
