Make a fun ‘kitchen scrap monster’ with earthworms. This DIY experiment will show you how to make a worm farm and give an understanding of the decomposition of food waste. Making your own worm farm is a great project for the classroom or to make at home with your kids.

This project is suitable for any year level to develop good recycling attitudes and understandings of how helpful worms can be in processing our food waste. It is a simple, cheap, kid-friendly, non-smelly, curriculum-integrated, money-saving worm farming project–the ultimate in recycling. Opportunities are provided for research into worm life cycles as well as their place in the food chain. 

Earthworms have a lot to teach us. Science experiments with earthworms can demonstrate how you can utilise compost to benefit your garden, along with what types of food that worms eat. They play an essential role in the environment, reduce waste and help vegetation grow by adding crucial nutrients to the soil. They are also interesting because they can regenerate parts of their bodies when needed.

Items that worms love to eat are bread, vegetable matter, paper serviettes, paper towels, coffee grinds. Avoid meats, juice boxes, anything waxed, plastics and animal faeces. The worms prefer smaller pieces, so large items like bananas peels should be torn up.

Making your worm farm

There are many ways to make worm farms and many commercial systems available. We created a kitchen scraps monster based on the 2-bucket worm composter. This requires materials and processes that are easily accessible.

You will need

  • 2 (or more) x 20-litre buckets (these can be old buckets you have at home – but ensure they are clean)
  • 1 x bucket lid (you can use the original lid, or make a simple wooden top for easy handling)
  • Mesh or shade cloth
  • A drill
  • 10mm spade bit and 5mm drill bit
  • Waterproof glue (or glue gun)
  • Fine sandpaper
  • Scissors
  • Water
  • Spray-paint, craft paint, googly eyes, pipe-cleaners and polystyrene balls
  • Newspaper 
  • Kitchen scraps
  • Red Wiggler Earthworms (approx. 100 worms)

Method

  1. Using the spade bit, drill holes around the outer top part of the bucket.
  2. Use the sandpaper to roughen up the surface around the holes in the inside of the lid.
  3. Cut 8 squares of the screen or shade cloth (large enough to cover the holes – roughly 4 x cm).
  4. Put glue around each hole and stick your squares or strip of the mesh over each hole – ensuring they are completely stuck down. Set aside to dry.
  5. Switch drill bits and then drill a series of holes in the bottom of 1 bucket.
  6. Spray the buckets on the outside with a plastic adhesive spray-paint.
  7. Have fun with your scraps monster and decorate it with googly eyes and pipe cleaner hair and painted polystyrene balls. 
  8. Place this bucket inside the 2nd bucket.
  9. Place the worms in the top bucket – if you have bought your worms from a worm farm supplier, they will come in a layer of peat moss – add all of this into the bucket.
  10. Add a layer of kitchen scraps.
  11. Add a layer of wet newspaper, and top with more vegetable matter.
  12. Top with more wet paper, or cardboard (torn up pizza boxes work well).
  13. Add more kitchen scraps each day and always top with a layer of wet paper or cardboard.
  14. Cover with a lid and leave in a cool, shaded area, so that it doesn’t dry out. 
  15. Once the food waste reaches the level in the bucket where you can stack another bucket on top of the worms, without squashing them, you can add another bucket – with holes drilled into the bottom. Just be careful not to add more than ±20 cm of kitchen scraps, because the worms can get crushed under the weight.

As the worms eat and grow, they will leave behind worm castings. This is the perfect organic fertiliser. The worms start at the lowest level and eat their way up toward the top. They leave the castings behind as they move. The excess water that has dripped through the castings will filter through the holes into the bottom bucket. This rich worm “tea” is a fabulous organic food for plants.

It’s best to feed worms once a week in small amounts. If you feed them more than they can process you will end up with a stinking compost bin as the garbage backs up.

Compost doesn’t smell. The foul odour comes from rotting food that the worms haven’t eaten yet. If you give them appropriately sized meals — not supersized entrees — they will eat the food before it starts rotting (and smelling.)

As the worms make their advance to the top of the unit, you may notice that their numbers are increasing. If your setup is even marginally successful, you will have worm reproduction. Earthworms are self-regulatory – they will reproduce according to the amount of food you feed them.

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