Yard and kitchen wastes represent approximately 30% of waste in the U.S. This waste stream can be composted to feed your garden. Whether you live in the country or a city, you can enjoy gardening and composting. Here’s how to build an indoor compost bin that will not only provide fertilizer but will actively engage you, your children, and even your friends if you choose.
Instructions for Making an Indoor Compost Bin
- Obtain an opaque plastic or wood bin with a lid. For a family of 1 to 2 people a 15 inch high by 18 inch wide by 24 inch long bin should be sufficient. A family of 4 to 6 people might need a 15 inch high by 24 inch wide by 42 inch long bin.
- Cut small (about 1/8 inch) holes in the lid about 3 inches apart.
- Cut small holes in the sides of your opaque bin to let the worms breath. The holes should be approximately 4 inches from the bottom of the bin and about 3 inches apart,
- Obtain a second bin that the first one will fit inside with an air space at the bottom between the bins. The air holes in the first bin should not be covered by this second bin. This second bin can be clear or opaque. Do not cut holes in this bin. This bin will collect the worm fertilizer “poop” as it falls thru the holes in the bottom of the first bin.
- In a separate container, prepare your bedding material by mixing carbon-producing materials like shredded newspaper, dry leaves, paper towels, and cardboard together. These are your “brown” materials. Make enough of this mix to fill the bin about 3/4 of the way.
- Wet the brown material until it is about half damp but not thoroughly wet or soggy.
- Add a few handfuls of soil to the brown bedding material.
- To your bin, add a layer of “green” material such as vegetable and fruit scraps, grass, coffee grounds, etc. Do not add meat scraps.
- Pour the brown bedding mix into the bin to cover the green layer.
- Add earthworms. The best kind of worms are called red worms, red wigglers, or manure worms. For the smaller bin, add about 1 pound of worms. For the larger bin, add about 2 to 3 pounds.
- Place the bin in a location that is between 40 and 80 degrees Fahrenheit.
- As food scraps or paper diminish, add new layers. You may stir the original layers to mix them before adding new layers.
Note, if you don’t use a second bottom bin, don’t cut holes in the bottom of the first bin. You don’t want your fertilizer or any liquid running out of the bottom of your container.
Harvest your Fertilizer
After a few months or when it starts to build up, remove any compost from the bottom bin and use it for your garden.
If you didn’t use a second bottom bin, dig down under your brown layer and remove your compost after a 3 to 6 months when the worms will have done their job and the original bedding has disappeared.
Indoor Composting Challenges and Solutions
If worms are escaping from the bin, analyze the bin to determine why they want to move out. Make sure the bin is not too hot or cold, too wet or dry, and is well ventilated. If the brown ingredients are too dry, they won’t decompose; and if they are too wet, the worms will be swimming and won’t be able to digest the greens.
If you notice fruit flies, make certain the greens are covered with the brown material. Fruit flies are attracted to rotting fruit but will not be attracted to fruit covered with brown materials, moist paper towels, or moist newspaper. You can also freeze any fruit scraps for a few days prior to adding it to your bin. Always bury any new green scraps well below the brown material.
If the bin develops a smell, it has too much nitrogen (green material). Add more brown material to balance the ratio.
