Vermicomposting is the process of using “red wiggler” worms (a special type of earthworm) and microorganisms (like bacteria, protozoa, molds and fungi) to convert organic waste into black, nutrient-rich humus, excellent for new plant growth. Whether you set up a small bin or invest in a large-scale vermi-digester system, food and paper waste can become fertilizer while reducing the amount of waste landfilled.
Worms feed on both the organic wastes and the bedding, converting all the organic materials into worm castings. How much you can feed the worms depends on the size of the bin. There are approximately 1,000 worms in a pound, and the worms can eat approximately half their weight in food scrap per day (e.g., 10 pounds of worms, or 10,000 worms, can eat approximately 5 pounds of organic waste per day). Worms also may double their population every few months.
Commercial worm bins can be purchased, or you can make your own worm bin from an 18-gallon storage box with holes, a lid and a drainage tray. Figure 4 shows two options for indoor vermi-composting bins: an 18-gallon storage-tub-style bin and the commercially-available Can-O-Worms Bin. Starter worms can be purchased for your bin; refer to the list of resources at the end of this section.
Worm bins will remain odorless, if you maintain the bin properly. The resources at the end of this section provide several tips and guidance documents to assist you to set up and maintain your worm bin.
Some helpful hints for small worm bin set up:
- Create a bedding mixture of 2/3 coconut fiber (soak in a bucket to allow to expand, then crumble it up – it should be moist, not dripping wet) and 1/3 shredded paper (no bleached or colored paper, soy ink only)
- Do not fill the bin more than 2/3 full
- Use chlorine-free water to moisten materials
- Start bin with one pound of red worms
- Empty out the bag of worms onto the bedding. Gently spread any clumps of worms around the surface. They are light sensitive and will quickly retreat beneath the top layer.
- Dig a hole, add the food scraps, and cover with bedding. Place the bin on the tray and put the lid on tightly. If the bin is too wet, simply add more shredded paper to absorb the excess moisture.
- Worm “food” may include small pieces of brown corrugated cardboard; fruit and vegetable food scraps cut into small pieces (easier to process); coffee grounds and nonbleached filters; crushed egg shells
- Bin mixture should only be 12” to 18” (30 to 54 cm) deep
- Bury food to avoid attracting fruit flies
- Avoid overloading the bin with any one food item – moderation is the key
- Worms need protein; occasionally feed them corn meal and crushed unsalted peanuts
- Slowly increase from a couple of pounds of food the first week to 4-5 pounds by the fourth week, as worms mate and multiply
- Excess water in the bottom tray can be used to spray on household plants
Illinois Department of Commerce and Economic Opportunity
The Adventures of Vermi the Worm
Item #36-080 – Gardener’s Supply
Worms by the Pound
Sarah Bush Lincoln Health Center
Jeff Nichols, project lead
Southern Illinois University
Andilee Warner, project lead