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Everything You Need to Know About Composting With Worms

by Rob Avis

Following my recent blog post on the Do-It-Yourself Vermipod, I’ve been receiving a ton of questions from folks who built Vermipods and are looking for information on how to manage and maintain their new pets. So here’s a compilation called Everything You Need To Know About Composting With Worms….

Common Worm Species

Eisenia fetida: Pronounced “iSEEnee a FETid a”, is a worm that can process a large amount of organic material in their natural environment. They tolerate large temperature, moisture and pH ranges and can also tolerate handling well.

Eisenia andrei is closely related to the Eisenia fetida and is known as the “red tiger”. This worm performs as well as the E.fetida, and it does not hurt to have a combination of both worms in your bin.

Lumbricus rubellus is another worm that can be used for vermiposting. Some consider L.rubellus to be the true red worm. It is also called the dung worm, or red marsh worm. This worm loves manure and compost piles but has also been found working the earth which makes it doubly effective as the two other worm varieties stay mostly at the surface of the soil. This worm is great to use in indoor vermipost systems.

Bedding Materials

Worms, like you and me, need both protein and carbohydrates to get a balanced diet. Carbohydrates for worms come from carbon-based bedding materials. To reduce the environmental footprint, try to choose a local material that is a waste product instead of buying something from far away. These can include:

  • non-coloured, non-glossy newsprint
  • coconut fibre for those living close to the tropics
  • peat, if it is a waste product (mined peat is not an environmentally sustainable product)
  • shredded office paper
  • colourless, gloss-less cardboard
  • unbleached paper towel that has been used to wipe counters without chemicals
  • toilet paper roles
  • wet wood chips in moderation
  • bark in moderation
  • moist straw
  • brown leaves
  • brown grasses

Environmental Conditions

Composting worms originate from warmer parts of the globe, typically in wet regions. They have evolved to stay above the soil where it is moist, but not too wet. Most of these worms are litter eaters, not soil workers, so it is important to provide them with a moist bed of litter and food. The Vermipod makes it almost impossible to drown the worms as it is designed to breathe and drain freely. The worms respire through their skin which is most effective when their skin is moist. The worm’s body is comprised of about 75% water, and therefore if you keep their bedding at the same moisture level, they won’t have to work as hard to breathe, eat, or process their food. To get 75% moisture in their bedding, take 1 kg of bedding and add 1.5 kg of water to it. If you are not the scientific type, take the bedding and add enough moisture so that when you squeeze it, only one drop is extracted from the bedding.

These are the conditions that the worms thrive in.

  • Temperature: 15 – 25 C
  • Moisture: 75%
  • pH: slightly acid
  • An aerobic environment, i.e. lots of oxygen.

How Much do They Eat?

Worms eat a little over their weight in food every day. This means, if you have 1 lb of worms, they will eat 1 lb of food every day. As your worm population increases, the amount of food you feed them will increase as well!

What do they produce?

Worms produce the most amazing amendment for the garden! Worm castings (their poop) is one of the most valuable products that you can introduce into your garden! It is like probiotic yogurt for your garden! Castings are loaded with beneficial microorganisms (see below) which build fertility in the soil continuously. They are very high in organic matter (also known as OM and soil carbon) and humates which are both extremely important to plant and soil health.

In addition to castings, the worms produce worm juice. This juice is also loaded with beneficial microorganisms which can be watered down and added to your vegetable and flower gardens. Some people are even using the juice in modified hydroponic systems and calling it vermiponics!

How do I Use The Castings & The Juice?

I really like to plant my seeds and seedlings with castings in the spring. If I have additional castings in the summer, I top dress my vegetables with castings and then apply mulch over them to keep the sun off. They are really powerful, so you don’t need to add much.

The juice can be watered down at a ratio of 10:1 and applied right to your plants. You can also add worm juice to compost tea’s which is a discussion for another post. In the winter time, I use it for my indoor plants in the greenhouse, or on my outdoor garden beds.

Sex Life of The Compost Worm

Illustration 1: from Worms Eat My Garbage by Mary Appelhof

These little composters are both male and female and are pretty promiscuous. According to Mary Appelhof, author of Worms Eat My Garbage, 8 of these worms can reproduce into 1500 or 1.5 pounds in as little as 6 months. If you extrapolate that, 1000 worms can reproduce into about 180,000 (180 lbs) worms in as little as 6 months if your have the right conditions. Worms reproduce by rubbing up against each other exchanging sperm which allows them to produce cocoons. These cocoons can contain as many as 3-4 worms each and can hatch anywhere from 3 weeks to 6 months depending on conditions.

Since worms reproduce based on the presence of the right conditions, if there is no new food or bedding, the population is too high, or the whole bin is full of only their castings, they won’t reproduce.

Because the amount of breeding these worms do is based on the proximity of other worms (the closer they are, the more bumping into each other they do), a smaller bin will encourage more breeding. If your goal is breeding, you could run a small bin to encourage the worms to reproduce, harvest the cocoons and transplant them into new bedding material.

Sizing Your Worm Bed & Buying The Right Amount of Worms

To size your worm bin, you need to know how much food scraps you are going to produce per day. You can do this by collecting your compost over a 1-week period and dividing it by 7 days. So if you collected 10 lbs of food scraps in 1 week, you would be averaging 1.4 lbs per day.

If you are using a conventional worm bin, Marry Applehof (Worms Eat My Garbage) recommends that for every pound of food you produce per day you require 1 square foot of worm bin surface area. So 1.4 lbs/day requires about a 1.4 square foot worm bin.

In this instance I would recommend buying ½ a pound to 1 pound of worms and breeding them up to meet your food scrap supply.


Availability of minerals in the soil is determined by the life in the soil. It is the soil life that facilitates trading of minerals with exudates (plant-produced sugars) from plants. If the specific microorganism that makes a specific mineral is not available, it has the same effect as not having the mineral available in the soil at all. As the worm system is a “probiotic” system, we can mineralize the castings by adding supplements to the system. I am not a fan of chemicals, so I try to add natural supplements that have multiple benefits. Because worms have gizzards, instead of teeth, they need to have some grit to help them decompose their food. I typically add a handful of rock dust every six months which provides the mineral supplement as well as the grit for their digestion.

How to Add Food

When you start your worm system, it is good start slow. It is easy to overload the system if you are not used to it. Also, worms are only one of the many critters that make the process work, and it takes time for these other critters to start working as well. If you have 1lb of worms, add ½ a pound of food every other day for a few weeks. Monitor the food on a daily basis to see how quickly it is decomposing. If it is building up and starting to smell, stop adding food until it is gone.

When adding food, pull some of the castings aside and bury the food under 2cm of castings and bedding. If you have no castings, make sure you cover the food with damp bedding material. Another technique is to mix the food scraps with damp bedding and wrap it in newsprint. Place this food gift into the vermipost bin and cover with more bedding. If you don’t cover your food with castings and bedding, you can end up with a bit of a fruit fly problem.

Harvesting vermipo
st Illustration 2
from Worms Eat My Garbage, Mary Applehof

To harvest the vermipost, stop adding food until the majority of it is in the form of castings. Remove the castings onto a plastic sheet and make fist sized piles. Make sure that the room where you harvest the castings is well lit. Worms hate light, so they will go to the centre of the pile to avoid it. Leave the piles out for 30 minutes to an hour and then start peeling the piles back until you reach the worms. Put the worms into a dark container and once you have them all separated, you can weigh them.

Will Worms Leave my Bin & Take Over my House?

No, if you feed them, they will stay right where the food is.

Will Worms Take Over The World if They Breed so Much?

No, worms cannot survive our winter and such will not take over our soil. An interesting fact about Canadian earthworms is that they are not native either. They were introduced from Europe.


Fly problem

If you end up with a ton of fruit flies emerging from your system there are a few things you can do to remedy the situation.

  1. Bury your food scraps under bedding and castings. The deeper you bury them, the less likely the flies are to lay eggs.
  2. Introduce beneficial nematodes
  3. “Gift” wrap your food scraps in newspaper for your worms
  4. Add lots of moist bedding on top of your worms
  5. Get a small milk saucer and add apple cider vinegar with a drop of dish soap. Place this near the Vermipod to trap the flies.

Odour Problem

An odour problem is your worms way of saying, “I have too much food”. Stop feeding your worms, add more moist bedding and wait for the food to be consumed!

Worm Resources


  • Worms Eat My Garbage, Mary Appelhof
  • The Worm Book: The Complete Guide to Gardening and Composting with Worms, Nancarrow, Loren


Verge DIY Vermipod Article

Beneficial Insects:


  1. Great article Rob. Thank you. There are some excellent resource books for worms generally and for Australia in particular there are David Murphy’s books “Earthworms in Australia” and “Organic Growing With Worms.

  2. hey, nice timely article. i’ve been keeping worms for about 6 months now on my balcony here in tokyo, and they are great. only problem is i get a lot of mold appearing on the food scraps, mold is common in japan. is this a problem (overfeeding?), or is it all part of the breaking down process?

  3. That was a pleasure to read, however just a query. Feeding paper to the worms is infinitely better than sending it to landfill, but isn’t recycling paper the more environmentally friendly choice? After all it would reduce the number of trees being felled (admittedly some are plantation sourced), and cut out many of the energy demanding and polluting steps involved in the paper industry.

    1. Hi Adam, I’m not sure about where you live, but I live in an area where shredded paper isn’t recyclable. So if you have little pieces or shredded confidential documents this would be perfect for your worms!

  4. Hi Rob,

    Nice article, really enjoyed it. Worms punch well above their weight. I don’t have either garbage or sewerage services where I live. Worms are great because they eat everything that the dogs and chooks don’t want to eat including the sewage, black and grey water! Nothing organic leaves the property and the vermicast and worm tea are awesome soil starters and conditioners. In addition to this the grass and weeds that grow from this provide food for the native animals and birds, which in turn provide me with scats for the orchard. Go the worms!



  5. Has anyone experimented with fermenting the food via bokashi before feeding it to the worms? The worms don’t actually “eat” the food before it’s predigested by the other microorganisms, and it looks like bokashi would accelerate that and help to prevent flies from reproducing in the waste before the worms can get to it. I had a bad vinegar fly issue with my basement bins that only recently ended once the worms finally processed the waste. Not fun!

    1. I have a better idea for you and it will get rid of your fly problem. Instead of waiting for fermentation just take your scraps and run them through a food processor. You are basically making a worm soup that is easily and quickly consumed by your little toothless babes. It’s like worms on speed.

  6. I’ve been doing this for years. A few additional tips:

    1) The only time I’ve killed a bin is by using shredded office paper. Don’t know if it was the bleach, sharp edges, or what. But you recommend unbleached paper towels for a reason, I’d say that would eliminate office paper by your own rules.

    2) Eisenia fetida will definitely escape into the garden in temperate climes. I’ve even observed them climbing stems of shrubs and fences during dewy evenings! What they do when they get out there is live under the thatch of the lawn or under potted plants, doing their same decomposition work. I’ve not read of this being a problem, but it wouldn’t surprise me if they were edging out native species somehow. Whether or not you think this is a bigger concern than doing something smart with your food waste is your decision.

    3) 100 worms will breed up to process a household’s waste no problem. Of course nobody sells them by 100, but if you can bum 100 off a friend, or if you’re building a new pile from an old one, 100 is all you need. Another way of looking at it is that if you’re using an old pile, you don’t need to get out every last worm and put it in a new pile. Did that a few times :)

  7. Excellent article Rob! Thx for putting that together so concisely. Hope you guys are both well :)

  8. Hi,

    I would like to introduce worms to my 50 acre property in the south east Tasmanian midlands (I’ve yet to find one). Can you advise me which species would be best suited.



    1. Perhaps also consider checking with local Agricultural bodies, David, to check that there won’t be a conflict of interest with introducing a potentially invasive species that is not local.

  9. Congratulations on this well written article. Iv’e been a professional worm farmer for more than 15 years now and really enjoyed your site.

    One tip on composting worms that have escaped during rain.
    Most of them are easily captured by placing a sheet of corrugated cardboard next to the worm farm on the ground. Worms love corrugated cardboard and they will crawl underneath it or even into it to feed.

    This way the worms won’t get stranded somewhere the next day and dried out by the sun or get eaten by predators. Try it, It works like a bomb and can save you thousands of worms

    Kind regards


  10. my worms are suffering from the huge amount of ants that attach them I pour water around the warm farm boxes but it seems they enjoy eating the juicy worms what can I do to stop the ants coming into my worm farm?

    1. I’ve often had ants present but they’ve never been a problem that I’ve been able to tell. They seem to come and go, depending on the conditions – type of food, season, moisture levels, I’d guess. What makes you sure they’re eating the worms? Are they large ants?

    2. Salut,
      Pour éliminer les fourmis : leur donner à manger des flocons d’avoine (dans les coins des litières). Elles mangent puis boivent et explosent. Cruel mais efficace.

      Web Edit Via Google Translate:-
      To eliminate the ants feed them oatmeal ( in the corners of litter ).

  11. What a great article Rob.
    I have written previously about how we keep worms at Pobblebonk but there is so much great info here that I am going to go and insert a link to your article.

  12. It’s a shame you don’t have a donate button! I’d without
    a doubt donate to this outstanding blog! I guess for now i’ll settle for bookmarking and adding your RSS feed to my Google account.
    I look forward to new updates and will talk about
    this website with my Facebook group. Chat soon!

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