DIY Flow-Through Composter: How to Build a Coffee Can Worm Composter
How to Make Your Own Worm Composter
Using a few plastic coffee containers and a few common tools, you can make your own stacked, flow-through, worm composter that you can use indoors. My homemade composter was able to make 15 gallons of worm tea!
Tools You Will Need:
- 3 plastic coffee cans with lids
- A small drill bit (a 1/4" bit will do)
- 8 one-inch wooden or plastic dowel pieces
- Stones (to hold down the leachate collector)
- Nontoxic moss
- Worm food
- Composting worms (I use red wigglers)
Step-by-Step Instructions for DIY Worm Composter With Pictures
Below is a step-by-step guide for making your own worm composter at home. I also included pictures for reference.
1. Drill Holes in One Coffee Can Lid
2. Drill Several Holes in Two of the Coffee Cans.
- The holes don't have to be in a symmetrical pattern, but you want enough to allow for drainage.
- Make sure to have a few holes near the edges so that you can insert the dowels to allow for stacking.
3. Insert the Dowels in the Holes Around the Edge
- Push the dowels snugly into the holes so they catch the sides of the can they are stacked on.
- I am using plastic screw anchors because I didn't have dowels handy.
4. Layer One Drilled Coffee Can With Worm Bedding
What I Use to Make Compost Worm Bedding
- Brown leaves
- Cardboard pieces
A sprinkle of healthy soil gives the worms food and helps jumpstart the composting process.
Moss balls are the preferred habitat for egg laying. Mine were literally speckled with eggs less than a week after I placed the worms in the container. They love moss and can be found in the balls every time I turn the bin.
Moss balls also retain a good amount of moisture without getting sodden. If you're afraid of disease and pests, try boiling the moss for several minutes before adding it to the container.
5. Stack the Coffee Cans
- Set the filled coffee can in the center of the three cans. This is where the worms go.
- When the center can has composted, start adding bedding and food to the top can. The worms will go through the holes in the top can and into the fresh bedding/food.
6. Remove the Moss Balls From the Center Bin
- Remove the moss balls from the finished compost. They contain lots of eggs.
- Place them in the new compost in the top bin.
Note the eggs in the moss ball above. There are several eggs attached to the moss. They cling firmly, and the entire moss ball can be removed and placed in fresh litter. My worms lay most of their eggs in the moss, not in the bedding or the food.
7. Make Use of the Worm Castings!
- Sift the center (finished) can to remove leftover worms and stray egg casings.
- Use the castings (poop) to make worm tea or add them directly to your garden or flowerpots.
- Happy worms make lots of poop. These castings are just right for houseplants, aquarium plants, and garden vegetables and fruits.
How to Harvest Worm Castings From Compost
Harvesting the worm castings is easy.
- Place the compost container in a large bucket, and pour rainwater through it.
- Do this until it starts to run pretty clear but not too clear. You want to get all the poo you can without diluting the tea.
- Run that liquid through a sieve to collect any worms or eggs that passed through.
This makes a great start to perfect worm tea, with the added bonus of not having to pick the worms and eggs out! The worms in this DIY composter made more than enough castings to mix up over 15 gallons of tea!
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2011 Jocelyn