Build a simple worm farm from recycled materials

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worm farm

stacked Styrofoam boxes make a great worm farm for your garden

A worm farm is a simple thing.

If you’ve never heard of one, a worm farm is like a  like a glorified composter, but with added benefits. A worm farm takes your unwanted organic compost and returns a great supply of liquid fertilizer and rich worm castings for your garden. The best part is they are extremely simple to make and use!

What you’ll need:

  • At least 2 Styrofoam broccoli boxes
  • A screwdriver or knitting needle or sharp tool for making holes in the Styrofoam box
  • Shredded cardboard
  • Straw or grass clippings if you can get some
  • Newspaper
  • A piece of old fly screen

Broccoli boxes are easy to acquire at your local supermarket or green grocer. They usually get thrown away daily. Ask the produce department and they’ll usually bring them out for you.

To start your worm farm you will only need two boxes. First you will need to poke holes in the bottom of one of the boxes. Trim the fly screen into a rectangle and lay it in the bottom of the box to stop solids going through the holes. Fill it about half way with bits of damp shredded cardboard, straw, damp shredded newspaper and a hand-full of dirt mixed through. This mixture is where the worms will live. They like a dark damp place – but one that’s not too wet because they breath through their skin! Place this box on top of the box that doesn’t have any holes. This lower box is where the liquid fertilizer will drain into.

Now you will need to acquire some worms. You need the thin red worms found in garden soil (not large earth worms). In a pinch you can buy them at a nursery or garden store, but if you know someone who already has a worm farm you can just ‘borrow’ a bunch. You will need about 500 worms to get you going. Eventually they will multiply. Place the worms into the living area of damp cardboard etc.

Place your organic waste such as kitchen scraps into the box. The worms will crawl up through their living area to eat the organic waste. Be careful not to put in too much too soon. Watch to see that the waste is getting eaten before dumping in too much. When you have more worms and they are eating a lot of waste, you can add more boxes. Make sure you put holes into the bottom of these additional boxes (these upper boxes don’t need the fly screen). The worms will still crawl up into the boxes to feed and then return down to their living area.

In the beginning when there is only a small amount of food scraps, you may need to lay a piece of wet newspaper just in the top of the box to keep the worms living area damp. If it’s too dry, they will vacate the boxes all together or even die. Eventually, the moister from the organic waste that you put in will be enough – in fact it may even get too wet! If this happens, just add a few more bits of dry shredded  cardboard. This will ‘soak up’ the excess moister.

As the worms wee, this drains down into the lower box. This is excellent liquid fertilizer. It will do amazing things or your vegetables.  I usually put mine right onto the soil around my tomatoes! Check your lower box often as you will probably have enough of this liquid fertilizer to use every week. Just lift the upper boxes off, drain the liquid off into a bucket, and replace the upper boxes. It is too strong to use directly on plants, so add plenty of water to the bucket before using it on your garden.

As the worms poo, these dark rich castings are a wonderful amendment to garden soil. They will help add nitrogen and mineral rich nutrients to your beds – which will make your veggies tasty and nutritious. Eventually the cardboard and straw living area will fill up with these castings. To remove them, we first have to give the worms a new living area so they will vacate the old box. Just start a fresh box with new bits of damp shredded cardboard etc. and place it directly on top of the old one. The worms will happily move into the new one in a few days. Now the old box is free to get the castings out and use on the garden bed. If there are a few worms in there that’s OK because worms are great for the garden too! But if there are too many worms, you probably didn’t wait long enough for them to vacate the old box. Just put it back and wait another couple of  days.

worm_farm

Your worms can move around freely in the boxes.

1. To start you will probably only need two boxes. One for the worms and compost and one to catch the liquid fertilizer. The worms will crawl out of their living area and up into the compost to eat.

2. If you find that your compost is backing up too quickly, you can keep the worm’s living area in the lower box and add boxes on top for your organic material. Make sure you poke holes so the worms can crawl up to eat (no need for the fly screen).

3. When the worm’s living area has filled up with their castings, it’s time to change the boxes over. First fill a new box with fresh material (damp cardboard, straw etc.) and place it above the old box. The worms will happily move into the fresh material. You can empty the old worm castings into your garden as a great soil amendment.

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8 Comments

  1. Posted November 21, 2009 at 8:22 pm | Permalink

    Great little article. Thanks

  2. Posted February 22, 2010 at 8:58 am | Permalink

    I want to thank the blogger very much not only for this post but also for his all previous efforts. I found http://www.simplethings.com.au to be very interesting. I will be coming back to http://www.simplethings.com.au for more information.

  3. TOni Bowen
    Posted September 24, 2010 at 1:28 am | Permalink

    Thanks so much, my worm farm looks fantastic! Just curious about adding the third box to the “Worm Tower”. Do I need to remove the flyscreen from the original living area, or put more in to the third box?
    My worm-wise kids are looking forward to adding the worm poo and wee to our vegie-patch!!!!!
    Thanks again,
    Toni

  4. Posted September 24, 2010 at 7:44 pm | Permalink

    You only need the flyscreen above the bottom most box (so that the worms DON’T go into the liquid (they’ll drown)… but be sure to poke enough holes in the upper boxes so that the worms CAN travel upwards through your box layers looking for fresher food to eat.

    Happy worm farming!

  5. Posted October 1, 2010 at 12:01 am | Permalink

    Great site, Zac! i like this stacking plan very much – looks really efficient and much easier & cleaner to use than my current red-worm bin system of one big lidded plastic Tupperware-type storage container with holes punched in the top and bottom.
    But don’t you have trouble with animals breaking through & into the styrofoam boxes? Here in northern CA, once a family of raccoons tore apart my heavy plastic setup to get to the juicy worms. Apparently they love them. I was so surprised to learn coons were strong enough to do that. I now upend a milk crate on top as a second lid so they can’t pry the original lid off, with a big brick in between the two to weigh it all down… unwieldy but effective.
    I’d like to use your system, but wonder about the coon factor. Thoughts?

  6. Posted October 1, 2010 at 12:40 am | Permalink

    Fortunately we have no raccoons here :) Possums can terrorize a garden (that’s why I keep mine netted) but I’ve never had any trouble with them getting into my worms (or compost)… yet?

  7. Dave
    Posted October 5, 2010 at 2:29 am | Permalink

    How close is the top material of box 2 to the bottom of box 3? How do the worms get into box 3? They can’t scale the interior walls of box 2 can they? Does material need to touch the bottom of box 3?

  8. Posted October 5, 2010 at 3:40 pm | Permalink

    This is something that I’ve been pondering recently. The design I posted was my own adaptation of a (commonly known brand) commercially made worm farm that comes in layers. Their instructions show that the worms can indeed scale the walls and get into the upper levels. I have done this successfully with my own commercial and homemade worm farms.

    That said, I was just at my friends the Guru of Worm Farmers house yesterday and he reckons that the worms will only live in the upper most area anyway and therefore the ‘bedding’ should be on top and they can go down to eat…. so now I’m thinking – go ahead and fill up the 2nd box until the material reaches the top… then start your third level and when you know all of the worms have vacated the lower section… just harvest the castings and you’ll be back at two levels.