Indoor Composting with Earthworms (Red Wigglers)

Earthworms are a fun and affordable way to compost food scraps indoors. They require only a few minutes of care every week, and turn your kitchen scraps into rich compost for houseplants or your garden. Deva O’Neil, a professor at Bridgewater College, and some of her students offered demonstrations on how to set up an indoor worm bin and provided guidance on earthworm care and feeding at some of the Harrisonburg Farmers Markets in 2016.

Buying Worms   Get red wigglers (Eisenia Foetida) from a source specializing in composting worms. has many suppliers. If obtaining them by mail, do it in fall or spring – the worms are sensitive to temperature and will die if it is too hot or too cold. For this reason, your bin cannot be kept outside or in an unheated garage in Virginia’s climate. Keep them indoors.

Choosing a Bin   To get started, fill your bin with barely moist shredded newspaper. When you add the worms, it is recommended to leave the bin in a lit area for a day so that they don’t try to escape. I have found that under-the-bed plastic storage bins, with tiny holes drilled in the lid, work better than commercial bins. However, since they do not allow for drainage, you need to have….

Moisture control is the most important part of worm care.  If the bin is too wet, the worms will try to escape.  Since adding food also adds water to the bins, you need to remove water on a regular basis.  The easy way to do this is to always keep a sheet of newspaper on top of the bedding.  Several times a week, replace the wet newspaper with a dry newspaper.  You can reuse the same newspaper over and over; the newspaper will dry out once removed from the bin.

Bedding   Worms eat their bedding, so you need to continually add more.  A handful or two of shredded newspaper should be added every week.  The newspaper does not need to be moistened first, because it will get wet after being in the bin overnight. Worms also enjoy corrugated cardboard (the plain brown stuff, not coated or colored cardboard), if shredded or in small pieces.

Food  Worms will eat vegetable and fruit food scraps, as long as they are not oily.  Food scraps should always be frozen for 3 days before being added to the worm bin, to prevent the hatching of fruit flies.  Freezing also makes the food easier for the worms to eat.

Start by adding a handful of food every week.  If the worms are eating all the food, you can gradually increase the amount.  If there is still a lot of untouched food after a week, decrease the amount so that you are only adding what the worms can eat.  It is easy to accidentally overfeed the worms, which causes the food to sit around and rot.  This makes for unpleasant worm bins.

It is recommended that you not feed worms meat or dairy products.  Also, feeding them watery fruits like watermelon and tomatoes will result in very wet worm bins. Apple cores, potato peels, squash rinds, coffee grounds and lettuce scraps are good choices for food.

Grit for Digestion  Worms make use of gritty material, like sand or eggshell crumbs, for digesting their food.  You can crumble eggshells into the bin to provide grit.  This does not have to be done often.

Harvesting the compost  After a few months, there will be inches of brown worm castings in the bottom of the bin. To harvest, tip out the contents of the bin onto a sheet of newspaper and form conical piles. Wait for the worms to dive to the bottom of the piles, then scoop the compost off the top. Reform the cones. Repeat until most of the compost is harvested. Put what’s left back into the bins and refill with fresh bedding.


Email Deva O’Neil– doneil[at]bridgewater[dot]edu

Recommended Reading

Sandra Wiese, The Best Place for Garbage: Essential Guide to Recycling with Composting Worms

More from Rhonda Sherwin, Extension Solid Waste Specialist, Department of Biological and Agricultural Engineering, North Carolina State University, here:

California winery hires earthworms to clean up its wastewater, Matt Weiser,, May 10, 2016

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