Worm Tea – What it’s All About 

I prefer to call this product Vermicast Solution and Enriched Vermicast Solution, but everybody else calls it Worm Tea so I yield to the majority, not because they're right but because I can't be bothered to try and change them. There are probably as many recipes to make worm tea as there are worms in a tin.  I find 5% solid vermicast by volume a sufficient base.  That is to say, 5 litres (or pints) of solid vermicast to 100 litres (or pints) of pure water.  By measure; not weight.  In my case, I use rain water from our roof which is as pure as you can get without going to distilled water.  The roof  is coated with a membrane, the gutters, downpipes and tanks PVC, so there is no hydrolysis and the water effectively pure.

You know of course that you must use tanks of inert material – once again so that there is no hydrolysis.  If you used zincalumed or galvanised tanks for example, your solution will be (maybe heavily) polluted with Zn ions which could have a harmful effect in certain situations.    But you probably all know that. 

If you want tea with a long shelf life, then you simply steep a bag or stocking (see below) of casting in pure clean water and give it a good stirring.    The micros will come into solution as will the amino acids and other plant growth stimulators - the auxins, cytokinins, gibberellins etc.   Your population of oxygen-demanding microfauna will be low, say 30,000 per gram of solution and so, the product will keep 30, 60 days, maybe more.   The story changes however if you want a high population.

I tie the vermicast into balls 50 - 75mm diameter in ladies stockings and suspend them in the solution.  Bigger volumes require bigger or more balls etc, but still no more than 5% of solid vermicast.    Be sure also that thenvermicast is fresh, not aged.   Then I use a submersible pump, and arrange the discharge pipe in the tank in such a way that it delivers to the surface and makes as much splashing as you can, simultaneously seting up a swirl so that I have mixing and aerating combined.   Splashing is a very effective means of dissolving oxygen in water.   These days good quality stainless steel submersible, solids passing pumps, are not very expensive.   That's just one way of doing it - there are many others - and they all seem to work.   Don't be discouraged by any big words and mystique surrounding the construction of these brewers.    Just remember, all you have to do is dissolve oxygen in water to support an increasing population.

The purpose of this whole exercise is dual.   A very secondary purpose is to liberate the soluble minerals from the solid vermicast. Secondary because these minerals are there only in traces and not significant.  The primary purpose is to provide a means by which soil and plant benevolent micros, particularly bacteria, can be exponentially increased.   

Now, as your bacterial population increases, they need to be sustained, both in “breathing” and in feeding.  The splashing of the pump usually provides enough oxygen entrainment but you can add air from an air pump if you wish.   Can’t do any harm and can only benefit.  If you do this, introduce the air at the pump as it sucks in the water, so that it is swirled and mixed thoroughly into the water by the impeller and then held inside the delivery pipe where more air is dissolved into the water.   BUT; you need to be a little careful here, if you introduce too much air in relation to the volume of water, you can cause the pump to cavitate.   If it does, you should hear this because cavitating pumps are very noisy, so you may need to fit a valve to your air line so that you can restrict your air flow if you need.   Be guided by your ear.   If you hear a vibrating sort of noise, then reduce the air flow further until the noise goes.  A cavitating pump won’t last long.  

So, you’re giving your bacteria plenty of oxygen.  Now you’ve got to feed them.   Bacteria are the richest source of nitrogen on the planet with a Carbon:Nitrogen ratio of 5:1 and you're setting out to make a nitrogen (very) rich solution !  So, feeding efficiently, you need a soluble feed with a C:N also of 5:1.  The cheapest source of soluble carbon is black strap molasses and the most prolific source of Nitrogen is urea.    Now, I know organic growers will probably bristle at the mention of the word, but we are using the urea to make bacterial food, not to act as fertiliser, and the formula of the manufactured urea is exactly the same as naturally formed urea which is CN(NH2)2.





If your “Organic Principles” won’t allow you to use the urea, just use the molasses on its own.  The system will work less rapidly, but it will still work, with the bacteria trapping nitrogen from the air (which is 78% N) by the action of bacteria designed to do that.  They are called azotobacters and if yu're relying on them, you will have to aerate longer.  I can't suggest how much longer. Dr. Thomas Barrett never worried about it and he made plenty of "tea'.   If you don't know of him, Google him.   He wrote "Harnessing the Earthworm".

By this method, in one example, benevolent bacteria in a solution, after 24 hours aeration/mixing, were increased from 32,000cfu to 360,000,000cfu per gram of solution (cfu = colony forming units). (See Page 110 of Organic Growing with Worms).   This is what you’re after in making the tea or solution – plenty of mobile, life boosting nitrogen-rich bacteria !    If your solution is loaded with 5:1 food when you apply it, then the bacteria go into the soil, taking their lunch box with them.   They have the opportunity to enter the soil, to soak down to the roots, and even to continue increasing their numbers while their food lasts.  But then, when the food cuts out, they start to die off.   That’s when the benefit starts to show.   When they die, they decompose to their component parts, basically just nitrogen and carbon. This is natural fertilisation at its supercharged best !

The nitrogen is taken by nitrifying bacteria in the soil and converted to nitrite - NO2,  then others convert the nitrite to nitrate - NO3, the form in which nitrogen can be taken up by plants. (This is a very small snapshot of the complexity of a soil biota). The carbon is released into the soil as carbon dioxide CO2.   Some of this is absorbed by the moisture in the soil, making carbonic acid, pH around 6.5 - 6.8 or so, which helps to regulate the Ph of the soil at around neutral. 

The rest of the CO2 percolates up through the soil and as it escapes most is captured by the stomata on the underside of plant leaves.   They are there for that reason and evolved in that position when the organic matter OM of soil was much higher than it is today - around 20% and higher - and the atmospheric CO2 - much higher than it is today.  

It’s worth adding here that most of our food plants are known as sub-optimal photosynthesisers.  Simply put, they're equipped to photosynthesise much more than they do, but they are not able achieve their full potential because there is insufficient CO2 to allow it.  They evolved during a time when atmospheric CO2 was at much higher levels than it is today, as much as 1000 parts per million (ppm).  This is why as atmospheric CO2 increases, crop yields do too but without an increase in chemical fertiliser application.  The higher the level of CO2 in the atmosphere, the better will be the yield of our crops.   

Back to our tea !  As with Biodynamics BD 500 (see pages 124 - 131 of Organic Growing with Worms), teas need to be applied out of direct sunlight, or on a cloudy day or at night.  This enables those bacteria which do not fall on soil, but on plant leaves, to establish a UV barrier before the sun comes out to kill them (Ingham, personal communication).   The tea is loaded with beneficial bacteria and food, so they can very densely colonise leaf surfaces.   One special member of the bacteria family are actinomycetes, special because they will also produce an incredible range of antibiotics, like Streptomyces, which then produce a further sub-species of antibiotics such as Erythromycin, Neomycin, Tetracycline and Cefoxitin.




Teas also have the ability to ward off flying pests, micro and macro.  Have you ever seen white butterflies (they are butterflies, not moths) land on brassicas recently sprayed with worm tea (enriched with 5:1 food or not) ?  They don’t !  They fly away.   I don’t know why.   Vermicast tea is odourless and tasteless, but it has that effect.

In application by spray, you will more than likely kill the bacteria if you use high pressures.  It’s not the pressure which kills them, it’s the sudden change of pressure as they leave the nozzle and enter the free atmosphere.  An instantaneous pressure change from say, 50psi to 15 may cause their bodies to burst.  They are tender littler creatures.  You can pump them out but make it a low pressure spray.  On my veggie patch I like to apply tea with a rose on a watering can, but that's very low numbers.  One customer used to apply it by helicopter, but still at low poressure.   On page 120 of Organic Growing with Worms there’s an illustration of a farmer (Davo Davidson) applying tea to his property through a low pressure fire fighting pump.  You can see that the rig he's using is not sophistocated or expensive and on the web page Home Page there's a big spray rig putting it out, but again at low presssure.   It’s just a question of what is most suitable to do the area you are working.  By using worm products like enriched tea, Davo has doubled the carrying capacity of his farm in under 3 years and the worm population of his soil has gone from close to zero to over 400/m2. It will only get better.

Now, the question of shelf life.   As mentioned above, if you make only a weak solution, you will have a much longer shelf life than the enriched tea described above.   Ideally, the enriched tea should be prepared just before it's to be used - just like Biodynamics. If you store your enriched tea in a stoppered container for too long, it will quickly use up the oxygen.  Bacteria use oxygen just as we do - to sustain life - and they need it in the same concentration that we do - around 20% of the atmosphere.    “Too long" may be as short as overnight if your population is high.   Kept refrigerated will be much better - it will stay aerobic longer.  

Most bacteria are facultative, which means they can change their hats according to their environment. Today they are aerobic, and the tea, sweet smelling.  Overnight, they use up the oxygen but they don't die.  They simply change their hats and become anaerobic and stink !  People say “It was sweet last night, I don’t know where the bad ones came from !”.  Well, they were there all the time, just waiting for the chance to ambush you !! 

So, what do you do now with several gallons of stink ?    Well, you can put the air back in by bubbling or pumping/splashing.  They’ll very quickly change their hats back to aerobic again.   Or you can just apply it as if it was still a sweet smelling brew.  Be sure you have no near neighbours though !

The stinking tea that falls on the soil is still full of bacteria, and even though it is now anaerobic.  The bacteria still have a C:N ratio of 5:1 and are still the richest source of Nitrogen on the planet.  Exposed to the air, they very quickly do a Marx Brothers hat change and return to aerobic.  Tea is an exceptionally robust product, intended to be aerobic and will always return to aerobic on exposure to air. 

Dilution.    You can dilute enriched tea with pure water, virtually as much as you like.  Go to 100 times – not 100%, that’s only two times -  1 litre or gallon made up to 100 litres of gallons by the addition of more water.  It will still work.   I have often seen 50 times used and it always worked well.  There’s a colour photograph of pasture at my place sprayed with 50 times diluted (plate 9) on the fourth of the colour pages in Organic Growing with Worms.  Look at that pic, compare and wonder at the power of this amazing product ! 

A little tip.    Once you have made your first brew, the dissolved minerals are so unimportant they are not worthy of consideration in these brews.  It's the benevolent bacteria and other microfauna and flora you want, even more so than the cytokinins, giberellins etc and amino acids.   This means that once you have made up one brew, you can then simply keep adding water and food, keeping it aerated and agitated.  The areation and agitation doesn't have to be any more than soldiers marking time.   Just use a small aquarium aerator to keep the air bubbling in your brew.  If you find you can detect an unpleasant odour, add another aerator (It all depends on how many gallons/litres you have).  That will be adequate to maintain a Master Brew, from which you can keep drawing supply.  If you want to sell at weekend Farmers Markets, and you have a trailer, you can make your Master Brew in one of those 1000L tanks so common these days and tow it to market in your trailer, aerating with an aquarium bubbler powered from your car electrics.  If you have some empty bottles, customers love to see their brew freshly drawn from the Master and soon, they'll turn up at market with their own empty container to be filled from your Master Brew.  It’s a good way to establish a rapport and long term relationship with your customers.  

There’s been quite a bit written and claimed about putting the bacteria to sleep, or into suspended animation as part of these magical liquid bio-brews.    Well, pigs might fly also !   I suppose it may be possible, but I haven’t seen it yet.    Maybe they hypnotise them !   All I’ve seen so far is smoke & mirrors, mumbo jumbo and bullshit !  Pay no attention and give them no credit. Above all, don’t feel that you’re not doing it right because you’re unable to do this yourself.    Nobody can !  You’re not at fault and you’re not failing in your efforts at becoming a competent maker/marketer of worm products !    As I’ve written above, the bacteria will change hats with bewildering speed so don’t worry about it.  People who make those claims are only weak marketers who think they have to surround their products with mastery (I think I'm smarter than you but I'm really a dill syndrome) and mystery.   It’s a clear sign that they don’t know their products and therefore lack confidence because the truth is much more exciting than their rubbish. 

One thing you can be sure of.  You will never kill or harm any plant with worm tea.   In fact, the reverse is the case.   I have applied it liberally to trees that looked entirely dead, dead, dead.  And some recovered.  One was a 150 year old beautiful Lemon Scented Magnolia in our front garden, which fell victim to a 10 year drought.   We couldn’t water anything properly because we had very little water in our tanks and everything in the garden died from the front to the back.  The Magnolia looked absolutely stark with only a few leaves left on it and if you bent a branch it just snapped as dead ones do.  After the rain finally came, some trees recovered, but not this one.   It’s actually a wetlands tree, and we’re in a low rainfall area, so it's not really in the right environment.  I made up 100 litres of enriched tea, and over a week diluted it 50 times and pumped it into the ground around the tree.  Within a fortnight it was showing leaf buds and now 6 years later is about 80% fully recovered.  I don’t think it’ll get any better.   I tried the same system on a couple of others, but, alas, the magic was not powerful enough !

I could keep writing for more pages and still not cover every question you may have.    There are no hard and fast rules with this product and it's very hard to make mistakes.    Remember it can go from aerobic to anaerobic to aerobic in conditions which you might expect all the bacterias to be killed, but it will still be good and you won't get sporulation.     

The process description above is good for 20 gallons or litres to 5000 and I have customers who have made batches of even more. Farmers use it to fertigate - use the diluted product to irrigate their vines and crops - and the result is clear. Just have confidence in it, make and use it any way you like and you'll be right.   A customer in South Africa rang me one night to very jubilantly tell me she had followed the instructions in my book and had trebled her millet yield in the first year !    Doubling of crops is common.  If you have more questions you can use gthe communicator on the Home Page.  Don't forget to include your email address and I'll get back to you without delay.     You can also use This email address is being protected from spambots. You need JavaScript enabled to view it.©