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04/03/2014 at 15:54

Hi Edd, when you say ready for harvesting what do you mean? How do you separate the compost from the worms?

04/03/2014 at 16:07

This is the difficult part Ashleigh. I have several methods depending on how much compost i have. 

The one i use the most is called the light method. I tip the compost onto a table i have outside and pile it into a cone shape. (just a pile really) Then i leave it for 1/2 hour in the bright light so the worms move to the bottom of the pile in the middle. They hate sunlight and try to get as far away as possible, into the dark. Then you just scoop of the top and leave for a while and keep doing this until you are left with a ball of wriggling worms to put back into the new bed. You can do this in a garage with a bright spot light. 

I will get some pics for the barrel method that i use when there is a larger amount of compost to be sieved.



04/03/2014 at 16:19

DIY worm harvester. There are several different system but this one is the best and the one i use.


04/03/2014 at 16:25

The plans are here. courtesy of Washington State University website.(freely) available

04/03/2014 at 16:46

Thanks Edd

05/03/2014 at 13:51

I really want to have a go at this, if you keep your container outside how much longer does it take compared to indoors? 

05/03/2014 at 14:32

The temperature indoors is constant so they are happy all year. Once the temperature outside gets to about 12 degrees everything speeds up dramatically. It all depends on the amount of worms and if they are happy with the conditions they are in. If they think there is enough food then they will reproduce at a astounding rate. Each worm can produce its own body weight in compost each day, in the right conditions.

I artificially raise the temperature of my outside bins by adding lots more coffee grounds as they heat up.

06/03/2014 at 22:21

Thank you, Edd.  Lots of info there.

07/03/2014 at 08:40

Hi Hester.

Let me know how you get on after you have mixed in the new bedding materials, please.

07/03/2014 at 12:57

Separating worms from casts. Continued.

  Most composting worms will not move away from the finished compost immediately unless you entice them to (although Eisenia Fetida are more likely to roam around). Slowly through time, the worms will move out to look for more food, but this can take many months.

It is really hard to create a 100% worm free worm cast product because there will always be some baby worms you will have missed out, or cocoons where new worms will hatch out from in the future. However there are effective ways to remove most of the worms from the compost to give you a good quality final product (and you will want as many worms back to start your next batch of vermicomposting).

Having a small number of worms in your final worm compost is not a problem at all!

In fact if you spread some of the worms with the worm cast in your garden it will be a bonus for your garden soil. Composting worms will not survive for very long if there is not a lot of dead organic matter around the surface, but for the time it is there it can help aerate the surface of the soil and continuingly add fresh worm cast in to the surround garden soil.

You can use food to entice the worms to move, and this can be done in two ways.


The first way is horizontal separation. This will be the best way to separate worms if your worm system is a simple tub or box. Imagine splitting your worm box in half down the centre. Feed on one half of the worm box only and leave the other half to rest. Very soon the worms will all migrate to the half with food leaving the other half without food to mature and harvest. Now once the other half is ready for harvest, swap the halves and repeat the process.

The other way is vertical separation, and is used for vertical stacking wormery systems.

These are boxes with perforated bottom trays which stacks on top of each other. As one tray is finished with the composting process, you will need to add another tray on top filled with food and new bedding. The worms naturally migrate upwards looking for food, and will crawl up through the perforated base into the new tray, leaving in the old tray harvestable cast free from worms.

Another method to separate worms from cast is to use the light method as I have mentioned in my previous. This is also a great method to use to further separate any worms which may still be in the cast after vertical or horizontal separation.

Worms are sensitive to light and will try its best to get away from it.

Grabbing a handful of the cast, create a pile on a covered surface and use a lamp to shine on to the cast pile or just use bright sunlight. Any worms will start burrowing down to the lower surface. You can now remove the top surface of the cast pile revealing the worms. With the detection of light, the worms will again burrow further down the pile allowing you to remove another surface of pure cast.

Repeat this process until you end up with a ball of worms.

You have successfully separated your worms from your cast!



07/03/2014 at 13:10


Just to clarify, worm bin reservoirs catch what’s known as ‘leachate’ – basically liquid (mostly water) that has drained down through the worm bed. Some mistakenly refer to this liquid as ‘worm tea’, and while it CAN be used in this manner (best if diluted though), it is definitely not as high quality as genuine worm tea. The best way to make worm tea is to soak high quality worm castings in aerated water. I will go into greater depth on producing worm tea later .


11/03/2014 at 14:02

Leachate/Worm tea.  

The liquid that drains from a vermicomposting system can be called whatever you want. I call it leachate as it has drained down through decomposing organic matter. It’s definitely NOT the same thing as vermicompost/castings tea.

When a system (whether stacking, single-compartment flow-through, or regular plastic tub with drain holes) DOESN’T produce leachate this shouldn't be viewed as a bad thing. IMHO this is actually what we should be aiming for! I’d much rather conserve my nutrients and produce a top notch vermicompost than be constantly collecting run-off from my systems.

Vermicompost/castings tea is created when you submerge high quality vermicompost in water (preferably not straight from the tap) and either let it sit and steep or vigorously aerate it. 

Leachate CAN be used as a liquid “fertilizer” of sorts, but the quality will be highly variable – depending to a large extent on how old the system is and how well maintained it is. Liquid coming from mature vermicomposting system that has been well maintained will likely going to be much better quality than a brand new worm bin operated by someone who is not all that familiar with the fundamentals of vermicomposting.

Because the material the liquid is draining from will be at varying levels of decompostion (and aerobicity), there can be all manner of different compounds (some of them potentially phytotoxic or worm-toxic) being added to the “tea”.

I recommend diluting any liquid that comes from the bottom of a worm bin – and potentially even aerating it for a period of time before use. I would also recommend only using it in your garden (vs small potted plants) just to be on the safe side.

Nevertheless i have achieved good results with worm leachate and can clearly see the positive impact it had on the plants i used it on but

when i started to brew “proper worm tea” using pure undiluted worm castings and molasses in the process i was blown away by the results.

In my humble opinion there can be no doubt that a freshly brewed worm tea is clearly much more beneficial for plants and soil than any run off liquid from even the best of worm farms.

Making worm tea does NOT need to be complicated!

Here’s how simple my tea was: fill a 5 gallon bucket with rain water and toss in 15 oz of castings(3 oz of vermicompost per gallon.) Keep it near the front of the house where I will walk by it a few times during the day. Leave a stick in the bucket and whenever I walk by, give it a good swirl to add oxygen. Viola!!! Wormcompost tea in a couple of days. I have also placed the compost in a cloth bag, and even a nylon stockings. Then dunk the bag repeatedly into the water.The vigorous dunking not only helped to get lots of ‘good stuff’ out of the vermicompost and into the water, but it also helped to aerate the mix.

Now for a my tried and tested approach.I do consider myself a bit of a worm tea guru.

Here is a basic supply list:

  • High quality vermicompost / worm castings. 3 oz of vermicompost per gallon. 
  • Some type of permeable bag – muslin bags or old tights 
  • Aged water – if you are using tap water you should let it sit for a day or two so as to remove the chlorine. Preferably, use some rainwater or pond water if you have some on hand.
  • A bucket 5 gallon.
  • A basic aquarium air pump and tubing – an airstone will help, but it’s not vital
  • a source of simple sugars – I use molasses (1 oz molasses per gallon.) and it works very well. This is used to help increase the population of beneficial microbes in the mixture
  • One hand full of materials like quarry dust/rock dust, kelp etc can apparently help to boost populations of the ‘good’ microbes, while adding some additional nutrients to the mix. I just use a hand full of Quarry dust or fine river sand if i run out of dust. 

I plug in my air pump ( powered by a stack of waggon batteries and charged with a very little wind turbine that i have knocked up at the top of my garage.) to start aerating the tea. I will likely leave it going for 24 hours or so. Then use it on the garden either through a watering can or a spray leaf feed.

The results will blow you away.Better, Greener, and Cheaper than any bought feeds. Magic stuff.

24/03/2014 at 18:55


24/03/2014 at 22:27

Hi, Edd. Thank you for doing this thread. I can't wait to get started! Will start my bin tomorrow and leave it to 'season', as you suggest. Off to find my worms, now. Night and thank you.

27/03/2014 at 01:33

Can you use sawdust in your worm bins?

The short answer to that question is no. Worms do not possess the digestive capability to process (and derive nutrients from) materials such as wood chips and sawdust. As is the case with 'regular' composting, it is important to keep in the mind the "carbon to nitrogen ratio" that i talk about a lot.

Pure sawdust has an extremely high C:N ratio (I've seen it listed at 600:1 or higher), not to mention the fact that it also has an extremely resistant structure - made up cellulose, hemicellulose and lignin, the compounds responsible for the strength and structural integrity of woody plants (one look at a giant Redwood makes you realize just how strong the combination of these materials must be!).

Woody wastes and debris tends to be broken down very slowly over time, primarily by fungi. This is not to say that you can't make sawdust and wood chips more worm-friendly and then use it as a food source. Some extra steps will however be necessary.

If I wanted to use some sawdust in my worm systems I would first mix it with something rich in nitrogen - farm animal manure would be a great choice - then let it sit for at least a few months to encourage some rotting. If you really feel like getting serious, you might want to try making large hot composting piles, assuming you have some equipment to help you turn them over periodically.

Another interesting possibility might be to use the sawdust to grow edible mushrooms, such as Shitake or Oyster mushrooms, which actually rely on woody materials for their nutrition. Then when your crop has finished fruiting you can mix the spent substrate (which will be full of fungal mycelium) with other worm foods, such as manure or food scraps, and start feeding it to your worms.

Wood digesting fungi such as these have specialized enzymes which aid in breaking down the resistant structure of woody materials, rendering them more prone to attack by other micro organisms.

Incidentally, some of the products derived from wood, such as cardboard, paper and newsprint are actually excellent materials for a worm bed, and can be broken down much more readily (even though they too have a very high C:N). Another strong argument for using these materials rather than sawdust is their high water holding capacity (in comparison).

Wood chips and saw dust can't soak up moisture the way paper and cardboard can, so apart from offering little nutrition they can't even be used as an inert bedding material (unless well rotted and mixed with other materials).

Something else to keep in mind if you are thinking about using sawdust or wood chips in your worm beds - even if you do mix them with manure etc and allow them to rot, you are almost certainly going to be left with some woody debris in your vermicompost.

For the casual vermicomposter this certainly isn't a big deal, but for someone who is keen to sell their castings this might be an important consideration since your final product may not look as finished as you would like it to (even if it may still be an excellent compost).



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