Extension Notebook: Consider worm composting this fall

Looking for a simple way to reduce food waste and create a nutrient-rich soil amendment for your garden? Consider worm composting this fall. Also known as vermicomposting, worm composting can easily be done indoors using a 10-gallon storage tote, making it an excellent option for year-round composting.

A worm bin can be conveniently stored under a kitchen sink, in a utility room, or in a basement. Because the bin is small and may attract pests such as fruit flies, always bury food scraps beneath the bedding and avoid overfeeding. Under ideal conditions, composting worms can consume approximately their own weight in food each day.

Red wigglers (Eisenia fetida) are the preferred species for worm composting. Unlike common earthworms, red wigglers thrive in shallow organic matter, do not require burrowing, and tolerate typical indoor temperatures. Composting worms can be purchased online or from reputable local vendors. Be sure to purchase the correct species for vermicomposting.

Building a Worm Bin

To build a worm bin, you will need:

• An opaque plastic storage tote with a lid

• One cup of garden soil

• Shredded newspaper

• Water

• 1/2 to 1 pound of red wiggler worms

• A drill

To set up your worm bin:

• Drill approximately 30 ventilation holes, each about 1/4 inch in diameter, in the lid of the tote.

• Fill the tote halfway with moist shredded newspaper. The bedding should feel like a wrung-out sponge.

• Add a handful of soil to introduce beneficial microorganisms.

• Add 1/2 to 1 pound of red wiggler worms.

• Place two or three small piles of food scraps beneath the bedding.

It may take several days for the worms to adjust to their new environment. Don’t be concerned if they do not consume much food during the first week.

Caring for Your Worm Bin

Add a small handful of fresh food scraps every three days, adjusting the amount based on how quickly the worms process the material. Always bury food scraps to help deter fruit flies and other pests.

Monitor the moisture level of the bin regularly. If the bedding becomes too dry, add a small amount of water. If excess moisture accumulates, mix in additional shredded newspaper. Because worms breathe through their skin, maintaining proper moisture is essential for their survival.

What to Feed Your Worms

Red wigglers readily consume many fruit and vegetable scraps, including:

• Banana peels

• Apple cores

• Watermelon rinds

• Coffee grounds

• Tea bags

Avoid adding:

• Meat

• Oils and greasy foods

• Bones

• Dairy products

• Highly acidic foods such as citrus, pineapple, and papaya

Harvesting Worm Castings

In about three months, your worm bin will produce finished compost known as worm castings. When it’s time to harvest, separate the castings from the worms and transfer the worms to a new bin.

One simple method is to place fresh food on one side of the bin and allow the worms to migrate toward it. Another option is to shine a light on the castings. Since worms avoid light, they will move downward, making it easier to collect the finished compost.

Once established, a worm bin requires very little maintenance until harvest time, making it an easy and rewarding way to recycle food scraps and create a valuable amendment for gardens and houseplants.

Nancy Kreith is a University of Illinois Extension horticulture educator serving Cook County.