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1. What is worm bin composting?

Worm bin composting (vermicomposting) uses red worms in an enclosed container to turn vegetable and fruit scraps into a nutrient rich soil amendment called worm castings.

2. What do I need for worm bin composting?

For more information about worm composting, contact OSU Extension Services Compost Specialists, or attend a worm composting demo.

3. Where should a worm bin be kept?

Worms are most active when temperatures are moderate, about 55 to 77 degrees. If the worm bin is kept outdoors, it will need to be insulated during cool weather with something like straw bales, carpet, mounded soil or ridged foam around the top of the bin. In summer, a shady spot will keep the worms from becoming overheated. A worm bin may be kept inside under a kitchen sink, in a laundry room or in a garage.

4. How does it work?

Worms eat half their weight in food scraps and about an equal amount of bedding each day. A bin that starts with about a pound of worms will need to be fed a handful of food every other day. As worms multiply, the food supply should be increased. Food should be buried about two thirds of the way under the bedding.

5. Do worm bins smell bad?

To avoid unpleasant smells, the worm bin needs to be operated with plenty of air circulation and the right amount of moisture. If the bin gets too wet, add more newspapers and turn the contents to introduce more air. Also, avoid overfeeding worms or giving them inappropriate food. Some tips for avoiding unpleasant odors are:

• Add only an amount of food that the worms can eat in a few days
• Add only the proper food items
• Keep bedding moist but not wet
• Maintain air spaces in the bedding

6. Will the worm bin attract fruit flies and fungus gnats?

The same conditions that produce odors can attract flies and gnats. A highly acidic content may also cause the problem. A light sprinkling of crushed egg shells or agricultural lime may be helpful in lowering acidity. Regular harvesting of finished worm castings can also minimize problems. To discourage flies and gnats:

• Bury the food waste in the bedding
• Lower the acidity of the bin contents
• Maintain odor control measures as listed in the "Do worm bins smell bad" FAQ
• Place several sheets of newspaper over the bedding

7. How are finished worm castings harvested?

Finished worm castings can be harvested in three to six months. There are several methods of harvesting. One convenient way is to move the finished compost (worm castings) to one side of the box and add new dampened bedding to the other. Feed only the new side. Place a black plastic sheet over the new bedding and expose the finished side to light and air. This allows the completed compost side to dry and encourages the worms to migrate to the side with fresh food. After about a month, most of the worms have transferred and you may remove the castings to use in plant mixtures. Add fresh bedding to the vacant spot and begin feeding again.

Another process that works well with kids is harvesting compost by the “dump and sort” method. Dump the contents, worms and all, on a surface. Divide the castings into several cone shaped piles. Wait ten minutes and start pulling the castings away from each pile. This will cause the worms to retreat to the center to avoid light. Repeating this process will result in a ring of castings surrounded by a pile of worms, which can be returned to the bin along with new bedding to begin the process all over again.