Vermi-compost mini-guide
by Koroxid


1. Vermi-compost and vermicomposting

  • Vermcompost is the product of composting using various species of earth worms, to create an organic fertilizer and soil conditioner rich of water-soluble nutrients, from vegetable and food waste and other decomposable organic materials.

Harvested worm castings
Harvested worm castings

  • Vermicomposting is one of the fastest way to recycle food waste into one of the most powerful organic fertilizers. It produces immediately a liquid fertilizer, the “worm tea”, while the end product after two months is a solid fertilizer, the vermicompost, also known as worm castings, worm humus or worm manure. These products are not only rich in Nitrogen, Phosphor and Potassium, like chemical fertilizers, but also contain more than 60 types of beneficial bacteria and fungi.

  • Vermicomposting requires specific worm species and basic understanding of their vital needs. It also requires appropriate feeding and regular monitoring. Compared to classic composting, vermi-composting is “clean” and sustainable, it doesn’t smell bad, and with a special vermicomposting system, the worms are even able act as natural pesticide or reduce and disable specific harmful bacteria and chemical components. Vermicompost is black and smells the fresh forest.

2. The Earthworms

  • Eisenia Foetida
    Eisenia Foetida

Eisenia foetida are the most adapted, used and known earthworm species for decaying organic material. Originally from Europe, they are also known under various common names, including red worms, brandling worms, tiger worms and red wiggler worms. They are different from common worms species found in gardens or forest. They are red with yellow stripes.

  • external image red_worms.jpg
They are epigeal, i.e. they live at the surface of the ground. They thrive in rotting vegetation, compost and manure. They can rarely be found in soil, and prefer conditions where other worms cannot survive. Other specific earthworm species are also adapted to vermi-composting, like Eisenia Andrei. More common species, e.g. Lombricus or Dendrei, can also be used but produces more slowly inferior quality compost.

3. Natural habitat


4. Identification

  1. Earthworm Identification (excellent guide) :
  2. Eisenia Foetida vs.Lombricus :
  3. Eisenia Foetida :
  4. Eisenia Foetida :

I – The six essentials

Survival, development and production of compost worms depend of their environment, and more specifically of six essential variables.

1. Air or Oxygen

  • Worms breath and need oxygen. They cannot survive in anaerobic conditions, e.g. a hermetically closed compost bin. For this reason, a vermicompost bin includes aeration holes. Inside the bin, the worms make galleries at the surface that help aerate.
  • Eisenia Foetida worms can hardly survive under 50 cm of depth. The content of a bin must be kept not too deep or compact. A compost bin that lacks air smells bad and the compost take a brow-yellow color.

2. Temperature

  • Ideal temperature is between 15° and 25°. Under de 5° and over 35°, the worms will stop reproducing and look for a more favorable place deeper. Under 0° and over 40°, the worms die massively. At the extreme temperatures, the ecosystem is also affected: organic waste stop decaying or the elevation of temperature may boost undesirable bacterial or insect’s activity.

3. Moisture

  • Ideally between 70% to 90%, the level a “wet sponge”. Less than 50% is dangerous dor the worms, and more than 90% can pose aeration problem (see first point) or encourage the population of certain parasites (e.g. Collembola, Acarid)

4. pH

  • Ideally between 6.5 and 8, worms can survive until 5 and 9. pH of a compost bin tend to naturally slowly reduce. pH can be adjusted with acid (e.g. coffee grounds, mosses, pine needles, grass, bread, etc) or basic food (e.g. ashes, egg shells, etc). Next section details the nutriments. Generally, a low pH is better than a high one, as basic pH tend to break ammoniac equilibrium of the environment. A too basic pH can generate bad smells and hurt the worms.

5. Light

  • Worms doesn’t like light. Light may not be critical, but in the sun, worms rapidly die if they dry. As soon as being directly led, they will try to hide. The inside of a compost bin must by in the dark.

6. Food and Carbone/Nitrogen Ratio

  • The content of the compost bin must be balanced between carbon material C and nitrogen material N. Carbon materials are often “dry” nutriments, and include cardboard, paper, plan leaves. Nitrogen materials are often “wet” nutriment, and include vegetables and fruits. Most nitrogen materials also contain carbon but at a lower concentration. When feeding the compost bin, a high ratio of C/N must be kept, which means much more carbon than nitrogen. A good compost must have 60% of carbon material and 40% of nitrogen material. For more detail on C/N ratio (or C:N ratio) see references.

7. Supplies for Vermicomposting for school and home.

III – Feed the worms

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Organic materials for vermi-composting : compostable materials

  • Materials rich in nitrogen or Wet materials

o Fruits and vegetables, raw or cooked without oil, peels, they love watermelon and melon. They like bananas and artichokes. The fruit can also attract fruit fly.o Potato peels: the worms love it, but can attract Fungus Gnat.o Coffee grounds and paper filters, grapes grounds, tea bagso Egg shells (preferably crushed), shells of nutso Cheese crusts, ham rindso Pasta sauce and fat-free radicalso Cereals leftovers cooked or raw (without fat milk or sauce)o Lawn and grass clippings (in moderation)
  • Materials rich in carbon or Dry materials

o Cardboard, papero Tissues, paper towelso Newsprint (beware of the toxic printing ink)o Dead leaves, dead flowerso Hay, Lawn dried plants, garden residues sweepero Wood chips or sawdust (in moderation)o Ash cooled (in moderation)o Stems soft plants, straw, weeds (without ripe seeds)Materials more difficult to composto Bread, rice, pasta without sauce, harder and longer to compost, and are quite acid. To put in small quantities.o Garlic, Onion: are quite acid. To put in small quantities.o Egg shells: Reduces the acidity of the compost. To put finely chopped.o Citrus fruits and barks, e.g. oranges : Citrus fruits may be added but only in small pieces. They are also very acid.o Corn: long to decompose.
  • Materials NOT to put in the composter (toxic for worms, plants or humans)

    • · Lemon: too acid.

    • · Meat, fish, bones dairy products: their biodegradation off a strong pungent odor and are toxic to worms.

    • · Fat (butter, oil) and products with gravy, cheese

    • · Plants with illnesses or diseases

    • · Plants running to seed, plant roots freshly uprooted: to regrow in the bin

    • · Plants treated with chemicals (e.g. treated turf)

    • · Plastic, metal

    • · Litter and animal excrement can be vectors of disease.

IV – Getting and using tea and compost

external image 0clip_image010.pngCompost teaIn the lower tray, the liquid flows is called compost tea is a natural liquid fertilizer. This liquid is water that has percolated into the compost, and was full of active nutriments. The top tray must be removed to get the tea in the bottom tray.

Compost is a bit more difficult to collect[[#_ftn2|[2]]]. First, make sure it is mature, or retrieve the most mature part. Then, to get the worms to restart the bin, compost and the worms inside must be separated. Once harvested, the compost can be stored for about a year before starting loosing its active properties. Mature compost is black, mossy and with small balls. It may look like a chocolate mousse or very dark earth.

To separate the worms, just spread a layer of compost to the bottom of a plastic bag and retrieve the surface while the worms will go deeper. Worms too small to be detected can remain in the compost, and continue to enrich it where it will be used. The following illustration explains the procedure:


Use compost and teaThe compost must be spread in layers of 1 cm on the ground to enrich. The passage of nutrients will be gradual when watering. To prevent it dry, this layer can be covered with soil. Compost can also be directly mixed with compost (10% mixed), and used for new plants. Compost tea must be diluted in 10x volume of water and poured in plants.
IV: Maintaining a compost bin and worms
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In this section we will only mention the levels compost bin model, probably the most appropriate for domestic or small scale composting, but many other models exist.
The binThe compost is a levels model. In this model (see above left), when a level is full, another level can be added, and the worms migrate to fresh food. It currently consists of two stacked tanks (see above right), but may be extended by similar containers (see above center). The lower tray (4), used to recover the liquid compost tea, is covered with a plastic bag to improve its seal. The top and center trays (2) serves to house the worms and compost waste. They have holes at the bottom, allowing the liquid to flow. At the sides holes are pierced for air and covered with a cloth to prevent insects from entering. Covering the bottom container, a plastic bag with holes (3) prevents worms from falling into the liquid. The top level of the bin is closed with a cover.
When the top tray is full, a new floor can be added (see above center). Just find the same size of polystyrene box (10kg) for the upper floor: Drill the bottom holes of 0.5 cm every few inches, drill vents on the side and close them with cloth. Then you can stack the new floor and put fresh food inside.
Regular maintenanceThe regular bin maintenance is to monitor the content, e.g. weekly, and correct the system if it is going wrong. Open the bin and prospect the contents to identify:
§ Presence of Compost tea.
§ Smell, compost color and moist level in the bin
§ Living populations and their global spatial distribution, proportion and evolution
o Adult worms and if they try to escape the bin
o Babies and young worms, signs of well being
o Microorganisms, e.g. Mold, Acarids, Collembola, Flyes (see nextsection).
Young worms are the best indicator of the good quality of the content of the bin. If everything goes well, they can be found everywhere. Young worms or cocoons resemble to white threads or brown balls of few millimeters. When things go wrong, the worms stop reproducing, and if it's going very bad, they will try to massively leave the bin, for example by taking refuge in the lower tray. Un bébé vers sort du cocon[[#_ftn3|[3]]]

Following table summerize the problems that can be found and theit solutions.

(1) Oxygen low
· Insufficient Air
· Compost is too compact

· Presence of bad odor
· Compost is a brownish color
· Aerate or mix bin content
· Add dry carbon food
· Stop the wet food

(2) Temperature
· Temperature too high or too low

· Micro-activity is much increased or reduced (e.g Acarid, Mold)
· Move the bin to a cooler or warmer place

(3a) Moist high
· Moisture too high

· Significant increase of Collembola population
· Lack of air symptoms, same as (1)
· Add dry carbon food
· Stop the wet food
· Aerate or spread bin content
(3b) Moist low
· Insufficient Moisture

· No or little compost tea produced
· Compost dries out
· Presence of ants
· Pour water
· Add wet nitrogen food
· Stop the dry food

(4a) PH high
· Too high or basic pH

· Ammoniac smell
· Worms avoid areas (e.g. around ash pile)
· Add acid food in small quantity
(4b) PH low
· Too low or basic pH

· Worms avoid areas (e.g. around an orange)
· Add basic pH food in small quantity

(5) Light
· Too much light

· Worms doesn’t consume or visit enlighten areas
· Cover or shade the waste or the bin

(6a) Food
· Excessive amount of wet nitrogen food
· Filament of mold on the surface of the compost
· Add dry carbon food
· Remove wet food
(6b) Food
· Insufficient Food

· All waste get consumed
· Worms migrate to the surface
· No Mold
· Add dry carbon food
· Add wet nitrogen food

V – Compost bin inhabitants

The vermi-compost is a specific ecosystem favorable for many detrivores, beside the worms. Some are necessary or beneficial to composting, such as Acarids and Mold. Others are harmful or just useless. All are annoying when proliferating.

Here are the appropriate response to each parasite :


Very low

Mold Filaments Overpopulation

Compost is too Wet
· add dry material
· stop or remove wet food
· remove mold

White or Brown Acarids Overpopulation


Collembola Overpopulation

Woodlouse Overpopulation
Too many wood
· remove wood
· add dry food
Ants Presence
Compost too dry
Presence of bread
· pour water
· add wet food
· remove bread
Fruit Fly Presence
Compost wet
Presence of potatoes
· 4 weeks of dry material diet
· Remove fruit
· Fruit Fly “Traps”
Fungus Gnat Presence
Compost wet
Presence of potatoes
· 4 weeks of dry material diet
· Remove potatoes

Beneficial detrivores benefits:

Mold. Molds are like bacteria, microorganisms that predigest waste. It is common to see them appear, especially at the start, mold form, in general, white filaments. They do not affect the correct functioning of the vermi-compost and disappear after a few days. Their appearance is often the source of a boost at the start of the vermi-compost.

White and brown Acarids. They measure less than 2mm. They are necessary but must not proliferate. They thrive when food is too abundant or very wet compost.

Harmless detrivores :

Collembola. Near visually white Acarid, can jump. Proliferate when the bin is too wet.

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ile:Meat eater ant feeding on honey02.jpg

Ants. Ants may come in the bin when the compost is too dry. They are also attracted by the bread or pasta.
Harmful detrivores:

Fungus Gnat. Tiny insects with wings that can be found in association with a rich and moist soil. Their larvae feed on decaying organic matter and fine roots of young plants they may damage. Their favorite food is potato peel.

Fruit Fly. It is distinguished by its brown body, one to two millimeters. They are attracted by fruits, where they lay their eggs and their larvae develop.

Woodlouse. Feeding on plants and dead wood. In humid environments, they may attack living plants when exceptionally fragile.

Avoid, get rid or simply reduce parasites population, several possible techniques:

1. Carbon and dryness cure: give only dry and rich in carbon material, e.g. cardboard, paper, etc., and maintain a low moist level, for at least 4 weeks.
2. Preventing infestation: you can freeze and defrost food before giving it to the worms, which kill larvae in fruits and vegetables. Keep tightly closed the bin can also restrict access to adult parasites.
3. Avoid food and conditions that attract parasites: Avoid the potato to fight against gnats, fruit against the fruit fly, humidity with Collombola, Acarids and Molds. Avoid bread and dry compost for ants.
4. Traps and tricks Controls: You can make traps for fruit flies, with vinegar or juice.
5. Physical Control: Eliminate physically parasites and infested food.
6. Biological control: Find the natural predators of pests and place it in the bin. For example, the nematode is an enemy of the Fungus Gnat larvae.
7. Random mix: Place in the bin of fresh soil and materials that can include natural predators of parasites.
8. Patience: The contents of the bin and the populations of different organisms may also self-balance themselves after a while.



1. (en) Christie, Bentley. X, Mark. "Red worm composting", website:
2. (fr) Wikipedia,, et
3. Fiche conseil :


2. (en) Monroe, Glenn. "Manual of On-Farm Vermicomposting and Vermiculture", Organic Agriculture Centre of Canada.
3. (fr) Insitut bruxellois de la gestion de l’environnement. « Guide pratique du vermicompostage » :


[[#_ftnref|[2]]] Voir aussi : et