Worm Farms (Vermicomposting)

One of our first Green Living projects was to start a worm farm.

Some of the advantages of a worm farm are:

  • It’s a disposal mechanism for most of your kitchen scraps
  • The earthworms turn the scraps into a rich compost
  • Moisture from the process drains through to provide “worm tea”. Worm tea is a liquid fertiliser that is extremely high in nutrients.

We did what we usually do and scoured the internet for every drop of information we could find. We discovered that worm farms come in all shapes and sizes. Basic, functional ones; curvy, fancy ones; three or more levels; domestic or “industrial” size. They come with or without worms, with or without stands, and often with a hefty price tag.

Side note: The greener we decided to go, the more “hefty price tag” became part and parcel of the results, particularly for a South African. Perhaps due to being of Scot ancestry, my lovely wife and I prefer the frugal route and try doing everything as cost-effectively as possible. Cheap is dangerous. Cheap often means “deteriorates quickly”. Cost effective might not be the cheapest item or approach but is usually an item that will save money in the long-run.

Ultimately we decided to make one. Why? For the challenge, for the cost saving, for the experience and for reliability. All those reasons may seem fair, but why reliable? Doing research turned up a few design flaws or concerns in some of the commercially available worm farms:

  1. First of all, the boxes are HEAVY when all those kitchen scraps are converted into compost. Some of the boxes we looked at were buckling and splitting under the weight of the compost when half full. Several had stands made from the same flimsy plastic that the boxes were made of.
  2. We didn’t want to subject the worms to a hot, claustrophobic ride with a courier. They are finicky little creatures at times. Too much heat, too little oxygen, too much moisture, too dry and they become compost themselves.
  3. The type of materials used to construct the commercial boxes was often unknown, or suspect. We preferred to manage that aspect ourselves.

That said, with a little care a worm farm, and its inhabitants, makes up a very hardy mini eco-system. Hardly any regular maintenance is necessary. It is one of the easiest things to manage.


Case study 1:

Our current worm farm. A single-stack farm consisting of three boxes as illustrated in the pictures below. Red “Kariba” worms were purchased at a local angling shop. A few years along and this one is still going strong. We regularly use the worm tea (diluted about 1:10 or more) on most of our plants. The compost is mixed with regular soil. We have had an extremely successful germination percentage this year. The veggies are shooting up and the potted plants have never looked healthier. At this stage both boxes are almost full. My wife harvests compost and worm tea on a regular basis.

Case study 2:

 An old-age home. We were approached by an in-law who works at an old-age home. The kitchen produces a large amount of kitchen scraps and disposing of them was a problem. She wanted four farms to start with. I designed a double stand (in the gallery below), and replicated our worm farm setup. I took some of the worms from my farm along with some of the soil, added a few kitchen scraps to see them through and delivered the farms. The boxes filled up quickly. The worms were adopted by several grannies who quickly stipulated “Googled” rules for their care. They are now probably the most spoiled earthworms in Pretoria and have likely been converted to Blue Bull rugby supporters too. Besides the rules, the worm farms get very little attention. It is located in a far corner of their garden out of harm’s way. So far no compost has been harvested, but the scraps are devoured and the worm tea is a winner.

Case study 3: 

A colleague. I was talking about our worm farm over breakfast at work one day. While probably not the most appetising of subjects, interest was piqued in one of the ladies when our manger mentioned that she also has one. My colleague asked me to build her one. A week or so later a single-stack farm complete with stand, worms, and kitchen scraps were delivered. She needs to give the farm very little attention and the worms are thriving. She recently tapped off her first worm tea. She loves the worm farm.


Our Requirements:

  • Cost effective
  • Efficient – it needs to keep up with our largely vegetable-based diet
  • Versatile – We must be able to use it to fertilise food plants as well as garden plants


Choice of materials:

  • Steel tubing, angle iron and flat bar were used for the frame.
    • Must carry the weight of three full crates
  • Black food-grade meat storage type crates were used for the boxes
    • Black was chosen to minimise the light in the boxes
    • Food grade was chosen because there are some opinions about the chemicals in some plastics leaching into the contents. This will ultimately be used for fertilising our own “organic” heirloom vegetables, so we didn’t want even the possibility of chemicals in the soil.
  • Food-grade taps were used to drain off the worm tea. The stop-cock type used in water canisters worked fine. They were cheap and freely available at the local plastic supply shop.



You can find tons of information on the web about making a worm farm. I have added the steps I have taken not to give you redundant information, but to put the information into a practical, tested series of steps and tips.

The pictures below tell some of the story.

  1. A steel frame, made to fit the lip at the base of the boxes, was welded together. If welding is not your forte, you don’t have the equipment, or couldn’t be bothered, a small sturdy table, or even a few bricks are enough to raise the height of the farm. The main purpose behind raising the boxes is to be able to drain the worm tea from the bottom box. Just make sure its high enough to place a container under the tap. The box WILL get heavy. Another reason is to make access easier on old backs. Make sure the farm is on a stable platform at an accessible height before it gets too heavy. Our worm farm weighs in excess of 60kgs when all three levels are full.
  2. The first level consists of the first of three boxes. It must be water tight and be fitted with a tap.
  3. The second level is added. Small holes are drilled into the bottom. Do not make the holes too small (they will get clogged), but be careful not to make them so big that all the earth falls through. Inevitably some worms find their way into the bottom bin. To counter that I obtained a plastic mesh to lie at the bottom of the bin. This optional step strains the water out but retains the bigger bits and worms. You will start filling up this box first.
  4. Level three is the final level. Level three will also have holes at the bottom, but no mesh is necessary. Level three also has a lid to keep the box dark once the worms start processing the waste in that box.
  5. The lid should close the top sufficiently well that light does not enter the box. It can be hinged with cable ties or two small key ring split rings.



Worms can be ordered online, but it is easiest to buy a punnet or two of red “Kariba” worms from an angling shop. Apparently these small red worms are the most suited to the worm farm environment. We have not tried the medium-sized variety most people find in their gardens but I hear they can be an option. We also haven’t tried the snake-like huge earthworms often found near the coast. My wife is dying to see whether they will work. Anyone tried them yet?

As your worm farm matures, you may find a horde of other bugs moving into the environment. These may include beetles, fruit-flies and their larvae, ants and more. I leave them be unless the ants become a problem. Generally the ants leave the worms alone, but if they become a pest, or you prefer to keep them away, try one of the following methods:

  • Surround the legs of whatever the worm box is standing on with water – but standing the legs in water can cause the legs to rot/rust/perish so it is not the best idea. An uneven stand could bring the whole farm crashing down.
  • Place a ring of mineral-based grease around the legs. This will prevent the ants from climbing up. They will not want to get caught in the sticky mess. You will need to refresh the grease every now and again as it hardens. It probably isn’t the most environmentally-friendly option though. Dont use animal fat/grease. That will just attract more bugs.

Or you can take my approach – leave the bugs be. You are ultimately trying to create a balanced eco-system. For the advantages of a balanced worm farm, a few bugs are not going to “bug” me. I do not usually get an excess of any bugs in any case as long as the waste is well covered and nobody detracts from the vegetarian diet.

Flying bugs such as fruit flies can be limited by covering the kitchen waste with a layer of damp newspaper, egg cartons, or cardboard. This is a necessary step anyway.

DO NOT spray the bugs with insecticide to get rid of them. Besides adding unhealthy poisons into your fertiliser, you might end up killing the worms too.



The worm farm should be placed in a cool (but not cold), sheltered spot out of direct sunlight. It should preferably be out of the rain as you do not want to flood the worms, or fill up the bottom until it overflows and wastes the worm tea. If the worm farm is functioning properly it should be odorless. Some people even keep the farms inside. I rather keep it near the back door under the awning, so that is close to the kitchen, but not in the way. I also make sure that the animals cannot get to it. Some of the dogs and cats seek out vegetable scraps at times.



Some people put limits on what you can put in a worm farm. My limits stop at dairy and meat products. For no other reason than the fact that those two categories would attract unwanted flies. We do not generally have meat or dairy waste so it is not a problem for us.

  • Some say that root-type scraps (onions, carrots, potatoes, etc.) are not suitable. One reason is that the roots may carry root-borne fungi that you don’t want to spread to your veggie-patch/garden. While that may be a possibility, my response is that if the spores were on my food in the first place, they are in the ground already. We will just wash our veg properly before we prepare them. You might differ. It’s your choice. Do you really know the condition of the soil your store-bought carrots, etc. were grown in anyway? Our worms LOVE potato.
  • Dairy and meat attract the kind of bugs we don’t want near our living areas. Rotting meat and sour dairy doesn’t smell too good either.
  • Some say onions and citrus waste are not good for a worm box. The thought is that the acidity is bad. I have often put the pulp left after juicing oranges into the box. By the next day the worms are teeming over the pulp. I haven’t tested the soil acidity, but I have been using all vegetable matter so far and the plants love the food. Remember, I am not using the compost alone. It is a bit rich, in my mind. I mix it with the soil where the plants are to be planted.
  • Generally though, there is no harm in being cautious. If you prefer to leave out the roots and citrus, it is up to you. All other vegetable matter is fair game.
  • Egg shells are good for the soil. Crumble them up finely before adding them.
  • Damp newspaper, egg cartons, etc. is good mulch for the compost. Cover the waste wall-to-wall and let it eventually disintegrate into the soil. Lift a corner and place new scraps under the newspaper. Once the paper starts tearing when you lift it, start placing scraps on top. The worms actually seem to love the paper as much as the scraps. Keep it moist though.
  • Keep adding waste food. Slowly at first. Adding too much to a starting farm can end up with rotten, mouldy food getting really smelly.



One of the rules my wife put in place right up front was that “Red” was not to be used for fishing.
“Which one is Red?” I asked.
“All of them,” she replied firmly.

  • Take care not to use the worm tea undiluted. It might be too rich for some plants.
  • Do not use the worm tea for delicate plants such as orchids and air plants.
  • Do not spray/place insecticides near the worm farm.
  • Do not let the worm farm dry out, or run out of scraps.

Post project rumination

Mistakes made that you might learn from:

  • I should have made a steel stand long ago. It’s just easier and more stable.
  • Shelter the farm from the rain. Water drains through, but overly wet soil kills the worms.
  • A mesh liner in the bottom box makes for less mess.
  • Use a suitable lid. Wood rots from the damp rising from the box.

Any you would like to add?
Pictures below: A double-farm setup for the old age home mentioned in the case study above.

This article is written in its entirety by us. It is a result of several years’ worth of researching and trial-and-error. If it shares ideas or facts with another website, it is unintentional.

Photos were taken by us and as such we retain copyright.

You are free to replicate the structure of the farm. We can make them for you, but we don’t want to limit you from trying something that has been proven to work! Please share a pic if you do make one. We would love to see it and get your opinion.

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