A worm farm is a simple and versatile home composting system that doesn't smell or take up much space – making it ideal for units, small backyards, and other settings in high-density urban areas. It is also simple and easy to maintain.
How does a worm farm work?
A worm farm consist of two or three trays.
The bottom tray collects liquid fertiliser, which is high in nutrients and can be diluted to a weak tea colour to use on your plants.
The other trays are the 'working trays' in which the worms live, breed and work, turning your kitchen scraps into rich castings which can be used as an excellent soil conditioner.
Good foods for worms
The following items can go into your worm farm:
- Fruit and vegetable scraps (see “bad foods for worms” below for exceptions)
- Egg shells (ground)
- Coffee grounds
- Tea bags and leaves
- Animal and human hair
- Vacuum cleaner dust
- Shredded paper (small amounts)
- Cooked leftover food, such as pasta and rice (very small amounts)
- Vase flowers
Bad foods for worms
There are some things that can make your worm farm sick, meaning that food won’t break down and your farm could start smelling and attracting unwanted guests such as mice and cockroaches.
The following items cannot go into your worm farm:
- Garden clippings, prunings, leaves, etc.
- Citrus fruits
- Onion and garlic peel
- Meat and seafood
- Dairy products
- Oils and fats
- Garden clippings
Tips for a healthy worm farm
- When getting started with a worm farm:
- Create a 10–15cm deep layer of 'bedding' for the worm farm using a mixture of shredded newspaper, leaves and finished moist compost or soil (or fibre material supplied with the worm farm). Add the worms to the surface of the bedding and cover the bin with a natural material (e.g. moist newspaper or hessian bag).
- Leave the worms for a few days to get used to their new home before adding any food.
- Make sure you start with small amounts of food, gradually increasing it week by week.
- Place your worm farm somewhere convenient where it can be easily accessed
- Keep your worm farm in a shaded spot outside or indoors – worms don't like extreme temperatures.
- Keep your worm farm moist – cover the worm bed with a hessian bag, damp newspaper or old T-shirt.
- Add food to worm farm in small pieces. Worms are very efficient and can eat the equivalent of their body weight each day, but smaller scraps are easier to digest (they have no teeth!) and will help them get through the food faster.
- Make sure the environment is not too acidic – ground egg shells help to regulate the pH inside the worm farm.
Harvesting the worm castings
Worms create a material called 'castings' when they eat food scraps. This is basically the organic material that has been digested by the worms.
Worm castings contain many beneficial bacteria and enzymes that can help in growing healthier plants, improving soil texture, and providing water-soluble nutrients to the plants. Worm castings have the texture of coarse coffee grounds or peat moss.
- Empty the worms and bedding onto a surface and scrape the castings from the outside as the worms move towards the centre.
- Use the ball of worms for a new bedding
Move all of the castings to one side of the bin, and add fresh bedding to the empty side. Many of the worms will migrate to the fresh bedding in a few days.
Once you have your castings, they can be used as plant food (add a 3–6cm layer around plants and cover with mulch) or to improve the quality of a potting mix (add 10–20% castings to a poor potting mix).
Worm farms also create liquid castings in the bottom tray, which can be collected and diluted with water (to a weak tea colour) to make a high-nutrient liquid fertiliser for your pot plants.
Worm farming workshops
The Green Living Centre runs worm farming workshops several times a year. You'll learn everything you need to know to set up and maintain your own worm farm.
Visit the Green Living Centre's Eventbrite booking page for a list of upcoming workshops.
Purchasing a worm farm
Residents can order a discounted worm farm and worms through the Compost Revolution program. Everything you need to get started will be delivered to you. Take the tutorial, do the quiz, and order your worm farming equpment. Please choose carefully as there are no refunds or exchanges.
Compost Revolution is supported by the Environmental Trust as part of the NSW EPA's Waste Less, Recycle More initiative, funded from the waste levy.
More information about worm farming
Visit the NSW Office of Environment and Heritage worm farming webpage for more information on worm farming.