Setting up a worm farm

A comprehensive step by step guide to setting up and looking after a worm farm. Every garden would benefit from a worm farm whatever it’s size, it’s a fantastic way to recycle used vegetable scraps and so much more. I will cover worm diet later, but seriously, if you haven’t got chickens a worm farm is the next best vegetable scrap recycle solution.

It makes the best soil fertiliser

I have both chickens and a worm farm, as I know the ‘compost’ worms which live in a worm farm and their ‘castings’ are a ‘gardener’s secret weapon’ and do a job nothing else can achieve and indeed make a fertiliser that is not matched by anything else either.

It makes the best worm ‘tea’

There is some controversy surrounding what ‘worm tea’ is, is it the ‘run off ‘ liquid found in the bottom bin or do you have to ‘make’ it from the castings by soaking them in water for an hour or so?

Any worm farm after a few months will begin to  fill the very bottom bin with a brown odorless liquid and while the majority of people, myself included,  call this worm tea and use it as such, always, always diluted to the colour of ‘weak’ tea, roughly 100 to one ratio. 

Some people refer to it as leachate and advise it can ‘burn and poison’ your plants because it is a product of an overly moist worm farm and contains undecomposed materials.

Well, in MY experience I have always used the run off in the bottom bin, and as long as it is really diluted, the weaker the better, as undiluted it will burn and poison you plants.

I have never ever had any problems, infact I have has such good results I am loathed to sell my ‘liquid gold’:) But I like to present all the information for you, so you can decide.

setting up a worm farm

Earthworms are ‘the unsung’ workers of a great soil.

We all know the humble earth worm lives below the ground, and really thats as far as if goes, they are just there!

Earthworms live in the deeper depths of the soil and they create tunnels to aerate your soil, they digest organic matter making it available in a form the plants can use, and they transform the mineral value of the Earth like nothing else.

But, they are definitely the heartbeat of a good soil, as they go about their tunneling activities they allow air to circulate around the soil particles and organic matter, this is vital for healthy plant life and did you know they can burrow to a depth of 1 meter or more!

As they burrow, they will swallow bits of soil, then regurgitate the bits to make ‘worm castings’. These worm castings contain 5 times more available oxygen, 7 times more available phosphorus, and 11 times more available potassium than the soil they originally swallowed.

No wonder all worms are considered the ‘gold’ stars of the soil, and their castings, are, for very good reasons, highly prized, as the best natural compost for any discerning soil.


What type of worms are used in a worm farm?

Compost worms are the kind used in a worm farm, these worms are naturally found in the first 30cm of the soil surface, and it’s no coincidence they are called ‘compost worms as it is their job to process the organic compost matter which is found in the surface layers of the soil.

There are many varieties of ‘compost’ worms and because they naturally call home, the upper layers of the soil a worm farm environment suits them perfectly, as they are shallow and contain a continuous supply of available food.

A Compost Worms Diet


Worms process their own body weight and some of organic matter each day,
they will smell all the vegetable scraps that might otherwise go to waste and
dutifully come to find their own epicurean delights. 

Compost worms will eat anything of plant or animal origin, and some people
recommend blitzing these scraps in their blenders first, but I have found the
worms like a bit of crunchy scraps to eat. So you don’t have to go to gourmet
levels of food preparation but it’s a good idea to cut bigger pieces up, things
like tougher stalks.

They will also eat their way through:

  • Torn up egg boxes
  • Used tea bags
  • Used coffee grounds
  • Crushed eggs shells
  • Shredded news papers
  • Grass clippings
  • Soft wood stems
  • Leaves
  • Vacuum cleaner bag dust
  • Animal hair

What NOT to feed your worms

  • They are not impressed with onions or citrus fruits as they find these too acidic, so it’s a good idea to keep anything with a ‘strong odour’ out of your farm
  • Raw or cooked meats and bones, these will only attract rats, not what you want
  • Dairy products for the same reasons as above
  • Dog poop, it is safe to add other animal manures (cow, horse etc) but only add it after ‘maturing’ it for at least two months beforehand. This is to evaporate the high amounts of ammonia that is found in animal urine which can kill a whole worm farm in a day. I find for this reason, it’s best to keep manure in a special pile or mix it in with your other compost items too big to fit in a worm farm.

What you need for the Set up

A dry protected place

A secluded corner near the house would be good, it’s quite hygienically safe and quite a sensible idea to put a worm farm outside your back door. This is as long as you keep your supply of food within the ‘rules’ of  what can go in and what can’t. 

The worm farm itself should not attract cats or dogs or rats also it should not have an odour where ever it’s positioned. If it does, you have either given them too much food and its rotting or the farm has gotten too wet and everything has begun to decay.

It is a good idea every three months or so to sprinkle a very tiny handful of lime on top of the uppermost bin compost surface, this adjusts the acidicy/alkaline levels and prevents any uneaten food from rotting.

If you find you are getting food rotting, you should notice this as you open the top lid, then add less scraps until the worm farm becomes established, this can take from two to five years and then can eventually support over 20,000 worms!

But, a secluded corner of the vegetable garden would not be such a bad idea as well if you don’t feel comfortable with it being close to the house, mines near the kitchen garden gate and away from the house only because this is the route I go to feed the chickens.

So I it easy to just pop some of the scrapes into the worm farm, but when I lived in the city my farm was outside the back door. Either way it has to be convenient so you will not find it a chore to feed your worms!


The type of bins needed

You can make the worm bins yourself or buy a ready to go structure. If you are going DIY, you will need three stackable bins made of plastic, wood or any other lightweight, waterproof material.

The ‘base’ bin will need to have a solid base, the other two bins will need a series of holes in their base so rain water etc can drain down to the base bin and the worms can move from one bin to another. The structure needs to fit ‘snuggle’ together so food, organic matter and the worms  don’t escape:)

If you want a ‘ready to go’ model, try your local council or nearest garden centre.


The three types of bin: Recap

The ‘base’ bin needs a solid floor to catch liquid run-off that filters down from
the upper bins and you will need a tap near the base. The tap allows easy
drainage to empty the base bin of the ‘worm tea’. I use old milk cartons to
collect my ‘tea’ in.

The two ‘upper’ bins bases need holes in them, to let the worms move up
through the floor to reach fresh food supplies. These ‘holey’ bins lock into each
other and are deep enough to leave enough room for the worms to move
about without being squashed.

To create congenial living conditions for the worms, you need newspaper
and soil to start the farm and a continuing supply of suitable food scraps.


Putting it together

Ok, you have chosen your location, got all the gear together, so lets put together the farm.


Put the base bin on the bottom of the stack, this is the bin without a holes in the bottom. Keep this ‘base’ bin empty, except for an upside down flower pot which must be deep enough to let the liquid run over it (it catches to ‘lumps’ form the liquid) but shallow enough so the lid fits properly.


On top of the base bin stack a bin with a holey bottom. You will have a spare bin with a holey bottom, keep this in a safe place, you will need this when this first bin is full of lovely worm castings.


Place some shredded egg cartons, paper and some brown leaves with a little bit of food. Oh yes add the worms as well!


Cover the top bin with a lid, I use a piece of iron sheeting, but you can use anything that is going to keep out the rain & light. If you allow too much water to get into the farm the worms will drown. 


Allow the farm to settle in for a couple of weeks before lifting the cover and putting in more food scraps.


Check on the bin’s progress and add more food scraps as the worms grow and multiply. Make sure that your worms have enough food, but don’t overfeed them – uneaten food will simply rot, resulting in a smelly farm and unhappy worms.

Looking after your worm farm

When to add another bin and remove a full one

When the top bin is full of worms and worm castings, put the extra holey bin on top of the stack, you will now have three bins insitu. Repeat the process of putting shredded egg cartons, paper & food scraps in the top empty bin. In about a week the worms from the middle bin will have moved up into the fresh food in the top bin.

Now it is time to remove the middle bin and use those beautiful worms castings on your garden or in your seedling potting mix.


Getting the right balance

Worms like moisture and should not be allowed to dry out. A light spray of fresh water when the worm farm is first constructed will generally provide sufficient moisture for the farm. Once the farm is settled in you should not need to add extra water. If you add too much extra water or allow rainwater to get into the bins, the worms may drown.

When to add more dry materials

I do this after a good rain or in summer time when the air corculation is dry and will quickly dry out the inside contents of the worm farm.


If you notice rotting food items or rotting compost, reduce the amount of food and check for water entering the worm farm, this could be from rain driving in from a storm.


Your worm farm should NOT smell bad, it should smell like outdoor soil/compost. Check what food items you are putting into the bin. Is there meat or bones or dairy products? Check if the farm is getting too moist or is it in direct sun, both of these can kill the worms and this could be the source of the rotting odour.