Worm Farming


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Hands holding a pile of compost worms
Hands holding a pile of compost worms
Composting worms

Also known as vermiculture or worm composting, worm farming is a great way to make your home more sustainable. It is probably the easiest way to deal with your organic waste at home if you don’t have a lot of space, and has many benefits for your garden.

It is similar to the composting process, but the organic matter is processed by worms. But, it only takes up a little bit of space, compared to the area needed for a well functioning compost heap, and you can install them in a courtyard or on a deck or balcony. 

Worm farms are a great way to deal with your food scraps at home. With a little care they are very clean and do not smell. 

As food scraps are processed by the worms they product vermicast (worm castings) and worm tea (aka worm wee). These are both highly nutrient rich and make fantastic fertilizers for plants as they have elevated levels of nitrogen, phosphorus and potassium compared to normal garden soil.

Getting started

  1. Choose a sheltered shady spot, that will not get too much sun, wind or rain. 
  2. Start the worm farm with a layer of bedding material: hay, coconut fiber, shredded paper or cardboard. The bedding should be damp and porous. 
  3. Add worms – 1/2-1 pounds of worms (approximately 1000-2000) is a good place to start. The worm farm will get going more quickly the more worms you add. 
  4. You can start adding food scraps and other organic material (check out the lists below of what worms do and don’t like).
  5. Cover the work farm either with a lid if you have a purpose-made worm farm, or if you have made your own then a damp piece of cardboard or wet newspapers will also work. Worms need dark to be active, but you do not want to prevent air from being able to circulate into the worm farm. 

What worms do I need?

For a successful worm farm it is recommended that you get special composting worms. Red worms or tiger worms are a good choice.

Compost worms are different from common garden earthworms that live in soil. Unlike earthworms, compost worms do not make burrows in the soil. They have evolved to eat rotting plant matter on the forest floor, and so live in the surface layer (around 12 inches deep).

They are perfectly suited to break down food waste and are great for worm farms because they will stay in the top layers of allowing you to remove the lower layers to harvest casting without losing all your worms. Compost worms can process their body weight in food scraps every day.

What do worms eat?

Add food scraps and other organic material regularly. Smaller pieces (no larger than 1 inch) will be eaten more quickly and so help to prevent odors.

Start off slowing only adding small amounts of waste. If worms are overfed the excess organic matter will start to rot. As the worm farm becomes established you can increased the amount of organic material added. 

What worms like to eat:

  • most fruit and vegetable scraps
  • coffee grounds
  • tea bags
  • dirty paper, tissues, paper towels
  • crushed egg shells
  • vacuum cleaner dust
  • hair

What worms don’t like to eat:

Worms will eat most kitchen scraps, but there are a few things that it is best not to give them if you want to keep your worms happy. 

  • Spicy food – chili, onion, garlic
  • meat products
  • dairy products
  • A large amount of cooked food
  • Garden waste (a little is OK)
  • Shiny (coated) paper
  • Citrus or other very acidic food

Adding a new tray

When the initial tray is full, you can add another to your worm farm.

Place new layer on top of the full one. You can add some more bedding material (this is optional, but can hep to keep the worms confined to the working layer, allowing for easier harvesting later on. Then continue adding kitchen scraps as you were.

Add food only to the new layer, and the worms will slowly migrate up top the top.

Looking after your worm farm

Worm farms are actually very low-maintenance most of the time.  However, there are a few key factors that need to be monitored or managed to keep a worm farm running smoothly. These are: moisture, acidity and temperature. 


Worms need a moist environment. The level of moisture should be similar to that of a wrung out sponge.

Checking that the worms’ surroundings are damp enough, and watering if needed is important to keep the works happy. 

Or, if it is too wet, you can add shredded newspaper or dry leaves to reduce the moisture levels.


Fruit flies, or white worms or bugs are an indication that the worm farm has become too acidic. 

You can neutralize the low pH with a sprinkling of lime or wood ash. 


Worms cannot tolerate very hot or very cold conditions. A temperature range of 50-85°F (10-30°C) should be tolerated OK, but for temperatures outside of this range, the worm farm can be protected with blankets to keep it warm, or shaded from direct sun to keep it cool especially during the hot summer months. 


As worm farms matures it will be time to reap the rewards of your hard work – harvesting that black gold worm compost for your garden! 

Harvesting Worm Tea

Collect worm wees through the drain hole at the bottom of your worm farm. Some have a sump, some have a continuous drip system. You can bottle it to use later, or pass on to any  organic gardener friend and family you may have.  

If you want to use the worm tea to feed seedlings or potted plants it must be diluted 1:10, to the color of weak black tea. Apply every 2-4 weeks.  

Growing your worm farm

When you filled up the first layer with food scraps you add another layer on top of the worm bin, and continue filling. 

When you have a few layers and the lowest layer is filled with finished compost (the bedding material is all gone) it is time to harvest the worm castings. 

Harvesting Worm Castings

When harvesting castings, you want to separate out as many worms as possible and keep them in the worm farm. A few being lost to the garden isn’t the end of the world, but they are more likely to survive in worm bins, and it is best to keep the worm bin well stocked with worms, so that you wont have to buy more in the future.

To harvest the casings, remove the top layer(s) and take the bottom layer out of the worm farm. 

The bottom layer contains casts. You can tell that it is ready as it will contain fine dark worm compost and hardly any worms (they move up the layers as more are added). 

Mix the finished compost into the garden soil to give your garden plants a boost of nutrients. 

You can also make worm tea from the dense worm castings by adding one part castings to ten parts water and mixing well.

Hungry bin continuous flow worm farm

Harvesting the worm castings from a traditional layered worm farm can be time consuming and difficult.

Luckily there is now an easier way! I have a Hungry Bin, which is a continuous flow system.

It is a bit like a regular wheelie bin, you keep adding kitchen scraps in the top, and the worm compost moves down the bin as it is processed. There is an access hatch at the bottom that lets you remove the finished compost, and a drain for the worm wees to drain out to a collection tray.

It is so easy to use I wouldn’t go back to the fiddly layered type of worm farm.

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