Worm Farm in a Fridge

The fridge ripe for farming

When I was offered the chance to come up with a design for a school garden I wanted to include a wormfarm. Kids love worms and a worm farm is a great way for them to see worms in action. Additionally, the worm-farm turns food scraps into rich compost and generates a liquid that can be used as fertiliser. Worm castings can be used as seed raising mix and worm juice can be used in the place of seasol when soaking seeds, transplanting or adding pep.

I had seen designs for wormfarms in a few books i owned. They needed to be dark, have a place to collect juice and castings and keep the worms cool in summer and warm in winter. Many people use old bathtubs which already have a plug for drainage but I wanted something with a lid.

Fridge lid with thermometer

An old fridge is ideal for a wormfarm because it is insulated and helps to keep the worms at the right temperature. They are cheap and a waste problem so seemed ideal. I bought a degassed fridge at the tip for $20 and removed all the shelves, motor, coil, screws and the fridge seal. The worms need to breathe.

I used the holes in the back of the fridge as a worm juice drainage point and fitted a bulkhead from the hardwear store so I could attach a hose to it to drain the juice into a bottle.

Brick in the fridge to reduce the area and assist drainage

I placed bricks and gravel to help drain the farm in the bottom of the fridge. This also reduced the depth of the food scraps. If the scraps are deeper than 60cm they can decompose thermally and stink. I then proceeded to add shreaded newspaper to the farm.

Shredded paper for Carbon in the fridge

Carbon acts like a sponge when composting. All the nutrients and other elements and minerals in your food gets broken down by the worms eating it and then binds to carbon in the farm. This results in rich humus being generated by the farm.

Paper and food scraps composted by the worms

Once we had placed a thick amount of newspaper we wet it slightly and added food scraps. The smaller the food scraps are the faster the worms can eat. I mounted an old mincer to add to the fridge to help the kids get into active composting. You don’t need to add water to the farm once it is working. The water the worms require will be added as the food scraps and too much water will make the farm anaerobic (no air) which is when smelly rot will occur.

I haven’t added vents for harvesting casting becuase the farm opens from the top. To harvest castings you push all the casting to one side and fill the other side with more ripped paper and food scraps. Once the worms eat all the food in the first pile they will migrate to the second pile. The first half can be harvested for use sowing seeds or fertilizing plants.

Worm castings and paper on one side of the farm

The worm farm is a crucial addition to a home garden. They are great as they can be made almost anysize and easily fit in the laundry. They require no turning like a conventional compost pile and dont smell if done correctly. Search on the internet for more ideas if your interested or ask me questions in the comments section.

Open worm farm sitting in the sun

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One Response to Worm Farm in a Fridge

  1. Sue Nott says:

    Hi Dan
    I didn’t realise the blog site was blocked on our school computers! The Department has now allowed access and I have sent a message to all Yarralumla Primary staff. Hopefully now you will get messages from the students and staff from our school computers.

    By the way the garden is looking stunning! You are doing a great job involving the children in the garden.

    cheers Sue

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