Getting Started with Worm Composting
Worm composting or vermicomposting is a great way to compost food scraps. It is suitable for apartment dwellers, homeowners and a great classroom activity. Plus you always have the added benefit of taking a few friends along to your favorite fishing hole.
Worm bins can be made from plastic tubs by drilling air holes in the tub. Plastic tub bins tend to get wetter than wooden bins. If the bin is too wet, odor problems occur and worms die or leave the bin. Holes can be drilled in the bottom of the tub. Set the bin on wooden blocks or attach legs to the tub to increase circulation. Worm bins can also be built from plywood. Our county offices have fact sheets available for building plans.
Supplies for worm composting:
• newsprint (limit color pages)
• cool tap water
• garden soil, about a cup (do not use potting soil; it may contain chemicals)
• one crushed egg shell
• worm bin (vented for good air flow)
• red worms (Eisenia fetida)
Bedding for the worms
Moist bedding provides the medium that worms need to survive. Shredded newspaper is the best bedding material because it is readily available, provides excellent moisture retention, and preparation is simple and fun for children.
Shred the newspaper by fully opening sheet, tearing it lengthwise down the centerfold, gathering the two halves, tearing them lengthwise again, and repeating the process until you have strips ranging from 1/4 to 1 inch wide. Put the shredded strips in bin.
Gradually mix the water, garden soil, and crushed egg shell with the shredded paper. The bedding should be damp but not sopping wet (about as wet as a wrung out sponge). Bedding should not be packed too tightly.
Add worms to the top of the bedding, leave top off of the container for an hour or so. Add 1 pound of red worms or "Red Wigglers" (Eisenia fetida) to the 2-foot-by-2-foot bin; and 2 pounds to the 2-foot-by-3-foot bin. Make sure you have good air circulation. Worms do best at temperatures between 55-77 degrees Fahrenheit.
Feeding the worms
Worms are really not picky eaters. They like most organic waste but will not eat anything inorganic, like plastic. They will only eat hard food after natural degradation softens it, don't exclude these foods, just do not be concerned if it takes a while for them to disappear. It does help if you break up or puree hard foods in a processor.
Red worms do not have teeth. Instead, they digest food material in their gizzard. The gizzard needs a small amount of grit to grind food. That is why you added the garden soil to your bin.
Many variables will affect how much your worms will eat. For example, they are more active at room temperature than at 40 degrees. A general rule is that worms will consume up to half their weight in food waste per day under ideal conditions. If you start with 1/2 lb. of worms, you can expect them to eat up to 1/4 lb. of food per day. Start with small bits of food until the worm population increases. Do not overload the system. Overfeeding can lead to odor problems.
Let's Eat! Suggested foods for your worm family
- Coffee filters
- Corn meal
- Egg Shells
- Tea bags*
- Coffee grounds*
*Acidid Food: Feed in small quantities only, may produce odors and attact undesirable insects.
Do Not Feed This to Your Worms!
- Heavily salted foods: Salted peanuts, potato chips, etc.
- Manure from dogs, cats, or horses. Horse manure may contain wormers or antibiotics
that will kill your worms.
- Animal feeds: They may also contain antibiotics.
How to harvest worm castings
Before long you will notice increasing amounts of worm castings, usually 3 - 4 months after starting bin. Besides the educational benefits, this is one natural reward for your composting efforts.
Casting compost is one of the best natural soil additives available! You can compare plants and vegetables grown with castings to those grown without as another educational opportunity that can be explored. It completes the recycling loop and illustrates how important worms and other organisms are to the balance of our ecosystem.
Dump and Sort Method
- 1 small plastic sheet
- Light source (either a lamp or bright overhead fluorescent)
- Prepare fresh bedding as described earlier.
Empty the contents of your container onto the plastic sheet. Add freshly prepared bedding to the container. Position the light source over the casting pile. The worms will move down into the castings. Carefully pick the castings from the pile in layers, working toward the bottom center of the pile. Place castings in a separate container. Continue this procedure until there is only a small pile of castings with worms beneath it. Add this pile and worms to the fresh bedding in your worm container. Use the harvested castings for a classroom horticulture project.
Split Harvesting Methods:
If the above method seems like too much trouble, you can simply add 2/3 of the castings (worms and all) directly to your garden. Add the remaining 1/3 to your fresh bedding. This will inoculate the bedding and provide some worms to get you going again, but it depletes your worm population for a while.
If you don't want to lose any of your red worms (they can be expensive); try this method. Don't feed the worms for a few days. Move all the decomposed bedding and worms to one side of the bin. Add fresh bedding to the empty area, moisten the bedding, add some soil & egg shells, and then bury food in the new bedding. The worms will start to move to the new bedding to feed. In about a month you can remove the worm castings and use them in your garden. When you remove them, you may need to add some more bedding.
For additional information please contact your local extension service office.
Learn more about composting from our specialists.
By Sherrie Sanders, ag agent, White County