University of Florida

Vermicomposting

Most people know you can build compost bins to recycle plant waste into usable organic matter for your garden. But did you know you can use worms to do your composting for you?

Vermicomposting uses worms to turn food waste into nutrient-rich compost called worm castings. Worm bins can take up less space than traditional compost bins and can even be kept inside. Vermicomposting is a great way to compost if you live in an apartment or if your main source of compost materials is kitchen scraps.

Making a Worm Bin

Worm bins can be purchased pre-made or constructed at home. If you choose to make your own, follow the instructions below.

Materials:

  • 14-18 gal. plastic (opaque, not clear) or Styrofoam container with lid
  • Window screen (used or new)
  • Duct tape
  • Bedding material (e.g., shredded newspaper, paper, or paperboard)
  • Water
  • A few handfuls of sand or soil
  • ½-1 pound of worms
  • Drill with a 1” bit

When getting worms for your worm bin, make sure you use red wigglers or African night crawlers. Unlike earthworms you may find in your garden, these worms thrive in worm bin conditions. They can usually be found at bait stores or local worm farms.

Construction:

  • Drill four holes (two holes on opposite sides) four inches below the top of the bin.
  • Cut pieces of screen to cover the holes and tape them inside the bin with the duct tape.
  • Fill the bin 1/3 full with 1-inch strips of bedding.
  • Moisten the bedding with water so that it feels like a damp sponge.
  • Add the sand/soil to the bedding surface.
  • Put worms on top of the bedding. After two hours, they should have wriggled into the bedding.

Using Your Worm Bin

One pound of worms can be fed half a pound of kitchen scraps per day. You can feed them daily or weekly. Make sure the scraps are in small pieces and buried under the bedding when you add them.

Worms can be fed scraps such as vegetable and fruit trimmings, coffee grounds, pasta, bread, and paper. Avoid animal products like meat, eggs, and cheese in order to prevent odors.

Make sure the bin is in an area out of direct sunlight where the temperature is 60 to 80 degrees. Keep the lid on the bin because worms do not like light and a closed bin will not attract flies.

Harvesting Castings

After two or three months, the worms will have turned the scraps and bedding into usable compost. There are two ways to harvest worm castings from the bin:

  • Push the compost to one side of the bin. Fill the empty half with moistened bedding and kitchen scraps. The worms will migrate out of the compost to the bedding with food. The compost can then be removed.

    Or
  • Dump the contents of the bin onto a piece of plastic (worms and all). The worms will migrate to the middle of the compost, away from the light. Scrape off the outer layer of compost. Repeat this process (let worms move, then scrape layer) until the compost is harvested and mostly worms are left. Refill the bin as listed above and add the worms.

Using Castings

Use worm castingsjust like normal compost. Add them to plants and gardens as a soil amendment, use them in potting soil, or make a compost tea.

Potting soil:
  • Mix ¼ worm castings, ¼ perlite, ¼ peat, and ¼ builder’s sand.
Compost Tea:
  • Place castings in burlap bag or pantyhose leg and tie off.
  • Place the bag into a bucket of water and leave overnight.
  • Use tea to water plants or as a foliar spray.
Adapted and excerpted from:

"Vermicomposting," UF/IFAS Florida’s Online Composting Center (accessed 10/2012).

L. Barber, "Vermi-Composting: Where the worm squirms and you benefit!" (80KB pdf), UF/IFAS Hillsborough County Extension (accessed 10/2012).

Compost Bin

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