Every year, Australians throw away a staggering amount of food – around 7.6 million tonnes, which is roughly 312 kg per person! When this food organic waste ends up in landfill, it rots without oxygen, producing methane—a greenhouse gas far more potent than carbon dioxide. By starting a worm farm, you transform your household scraps into a valuable resource instead of contributing to a massive environmental burden.

Why Worm Farm When You Have FOGO?

Many councils – like Randwick – now offer Food Organics and Garden Organics (FOGO) green bins, and that’s a great start. While FOGO is a fantastic initiative, backyard worm farming offers its own advantages:

• Zero Transport Emissions: You treat your food waste exactly where you make it – no trucks required.
• Liquid Gold (Leachate): Worm bins produce a highly nutritious liquid runoff (leachate). Diluted with water until it looks like weak tea, it serves as an incredible liquid fertiliser for your garden beds.
• Black Gold (Castings): Worm poo, or castings, is the ultimate organic soil conditioner. It is packed with beneficial microbes, helps soil retain moisture, and delivers balanced nutrients directly to plant roots.

How to Build Your DIY Bucket Worm Farm

Instead of buying an expensive plastic kit, you can easily upcycle 20-litre food-grade plastic buckets. Local cafes, bakeries, and restaurants often have these lying around from bulk ingredients (like olive or pickle buckets) and are usually happy to give them away for free.

What You’ll Need

• Two (or three) 20L food-safe plastic buckets (one with a tight-fitting lid) – you can use other sizes but generally speaking, the buckets all need to be the same size. Minimum 10L is good
• A power drill with a 6mm drill bit
• Bedding material: Shredded paper, or coconut coir
• Composting worms: Around 250g to 500g of Red Wigglers or Tiger worms (Note: standard garden earthworms will not work!)
• Hessian (or shade cloth): (to stop castings falling into the lower bucket)
• Tap for bottom bucket: Optional to harvest leachate

Step-by-Step Assembly

1. Prep the Top Bucket: Take one bucket and drill 10–15 drainage holes into the bottom. Drill another row of holes around the upper rim of the bucket for ventilation.
2. Prep the Bottom Bucket: Leave the bottom bucket completely intact. This bucket acts as the reservoir to catch the leachate.
3. Nest the Buckets: Place the drilled bucket inside the solid bucket, resting it so there is a space at the bottom for liquid to collect.
4. Prepare the Hessian: Cut a round of hessian the same size as your bucket bottom. Place this inside the bottom of your top bucket.
5. Prepare the Bedding: Soak your shredded cardboard, paper, or coconut coir in water, then wring it out completely. It should feel like a damp sponge. Add a 10–15 cm layer of this bedding to the top bucket.
6. Add Your Worms: Gently place your composting worms onto the bedding. Let them settle into their new dark home for a few hours.
7. First Feed and Lid Up: Add a small handful of chopped kitchen scraps, cover them with a damp sheet of newspaper/hessian or anything that will break down (a “worm blanket”), and pop the bucket lid on securely.
8. Place the Bucket: Place it in an area you can access easily when you need it. Make sure it isn’t in direct sun as your worms can cook.
9. Harvest the Castings and Worm Juice: Once the top bucket fills up with castings, you harvest the compost and restart. See notes about when to harvest leachate below.

Worm Farm Maintenance & Troubleshooting

A healthy worm farm should smell earthy, like a rainforest floor. Problems are usually easy to fix.

Common Problems & Simple Solutions

Problem	Cause	Commercial Solution	Home-Made Solution
Sour, Rotten Smell	Too wet, or too much food rotting before worms can eat the bacteria that eats it.	Buy a Worm Farm pH Neutralizer or agricultural lime from a nursery.	Stop feeding immediately. Gently mix in dry shredded cardboard to absorb moisture. Sprinkle half a teaspoon of crushed eggshells to balance acidity.
Fruit Flies & Pests	Food scraps are exposed and attracting flies.	Purchase a commercial hemp or coir Worm Blanket.	Always bury your food scraps under the bedding. Cover the top layer with a damp, thick layer of newspaper or old cotton towels.
Worms Escaping	The bin is too hot, too wet, or too acidic.	Buy a commercial moisture meter or aerator tool.	Leave the lid off under a bright light for a few hours (worms hate light and will burrow down) while you add dry cardboard to fix the moisture. Move the bucket to a cooler, shaded spot.

How to Harvest Castings

To harvest your worm castings without too much fuss, use the light separation method, which exploits the fact that worms absolutely hate bright light. Lay out a large plastic sheet or garbage bag in a sunny spot outdoors and empty the contents of your bucket onto it, shaping the material into a few cone-shaped mounds. Wait about 10 to 15 minutes; the worms will automatically flee from the light and dive deep into the centre and bottom of the piles. You can then gently scrape off the clear, worm-free outer layer of “black gold” from the top and sides of each mound. Repeat a few times as the worms continue to burrow downward. Place the dense cluster of worms at the bottom back into their refreshed bucket. Then repeat the bedding process above.

How to Use Worm Juice

When it comes to the safety of using “worm juice”, the answer depends on which liquid you are talking about. In the worm farming world, there is a big difference between leachate (the runoff that drips out of a working worm bin) and worm aerated compost tea (liquid brewed intentionally from worm castings). Here is what you need to know about safety and the ideal time to harvest both:

Worm Bin Leachate (The Runoff)

Leachate is the liquid that naturally collects in the bottom bucket of your farm.

Is it safe? Yes, but with caution. Because leachate passes through unprocessed food scraps, it can sometimes carry harmful anaerobic bacteria or pathogens, especially if your bin smells sour or bad.

• The Safety Rule: If your worm bin smells sweet and earthy, the leachate is generally safe to use. If the bin smells rotten or putrid, do not use the liquid on your edible plants.
• Never use it raw: Always dilute leachate with water until it looks like weak tea (usually a 1:10 ratio) (1 leachate: 10 water) before applying it.
• Avoid edibles: To be completely safe, apply diluted leachate to your lawn, shrubs, or ornamental houseplants rather than directly onto the leaves of vegetables you plan to eat raw.

When should you harvest it?

Harvest it as soon as it collects. Letting liquid sit in the bottom bucket for weeks causes it to go stagnant and lose oxygen, which encourages the growth of bad bacteria. Empty your bottom reservoir every week or two.

Worm Compost Tea (The Brew)

Worm Compost Tea is a liquid fertiliser made intentionally by soaking finished worm castings in oxygenated water (often using a small aquarium bubbler). Because finished castings have already been completely processed by the worms, this liquid is packed with beneficial microbes, completely stable, and gentle. It will never burn your plants or seedlings, even if applied directly to the roots or sprayed onto leaves as a foliar spray.

When should you harvest it?

You harvest the raw ingredients (the castings) whenever your top bucket is full. Once you mix the castings with water and turn on the bubbler to brew the tea, the ideal harvest time is 24 to 48 hours after brewing begins. This is the sweet spot when the beneficial microbe population is at its peak. You should apply it to your garden immediately after turning off the bubbler, as the microbes will begin to die off once the oxygen supply stops.

Different Types of Worm Farms

• The Three-Tier Migration System: Uses three stacked buckets. Drilled bucket 1 holds fresh food and worms. Drilled bucket 2 holds the castings. Whole bucket 3 leachate.
• The In-Ground Worm Tower: Drill large holes all over a single bucket, bury it into your garden soil, and top it with a lid. Place a brick on top of the lid. You feed the worms inside the bucket, and they travel out into your garden beds to deposit castings, fertilising your plants directly at the roots. I use old olive containers.