Composting food waste in worm bins is a great way to turn food waste into a nutrient-rich soil amendment right at home. When passed through a worm’s gut, organic matter such as food waste is transformed into a nutrient-rich compost by the microbial populations in the worm’s digestive tract. Worm bins are compact, easy to care for, and a fun way to make your own compost right at home!

Composting Food Waste in Worm Bins

Worm composting systems use red worms, also called red wigglers, to compost food scraps. Worm bins are well suited to urban/high population density and tight living spaces because they enable us to compost on small patios, or even under a sink and inside a bathroom closet. Worm bins:

• Are ideal for apartment-dwellers or people without access to an outdoor space  
• Produce high-quality compost   
• Are fun and interesting for kids and adults alike 
• Require harvesting and new bedding two to three times a year  
• Do best with regular feeding and careful monitoring  

Getting Started 

There are a wide range of worm bins available for sale, or you can build your own! Start by watching these how-to videos on building a wooden worm bin or an easy plastic worm bin, or follow the written instructions linked below.

To get started, fill the bin with slightly moist bedding such as shredded newspaper or paper, dried deciduous leaves, straw, or sawdust from untreated wood. Put a small amount of food waste in one corner and add your worms.  

Add only a little food at a time, especially at first. Red wigglers eat about their own body weight per week. Put the food into a different part of the bin each time you feed the worms. Disturb them as little as possible when you add the food. Make sure the food is fully covered with bedding.

What to Feed the Wigglers 

The diet of composting worms should primarily consist of plant matter. Vegetable scraps and fruits should be the majority of what goes into your worm bin (go easy on citrus and raw onions, though – these can be hard on the worms’ sensitive skin). Wigglers can also handle small amounts of dairy and grain. To avoid pathogens, meat and meat products, eggs, oils and fats, or animal wastes should not go into your worm bin.   

Previously cooked or frozen food works well – it can be more readily digested by the worms.  

Harvesting the Castings

After a few months, most of the worm bin will be filled with dark worm castings. To harvest them, empty the bin onto a tarp in a small pile; you can spread the compost across the tarp a little bit to make harvesting easier, but make sure there is a deeper pile in the middle for the worms. Leave it in the sun or under a bright light; the wigglers will avoid the light and travel to the deep center of the pile. Take the worm castings off the top and sides of the pile. Repeat until only the wigglers are left.  

Once you’ve harvested your castings, fill the bin with fresh bedding, add your wigglers back in and start feeding them again. 

Worms and Plant Growth

Vermicompost, or worm compost, has been shown to enhance soil structure, porosity, aeration, drainage, and moisture-holding capacity.  

Nutrients are transformed during their passage through the worm gut into forms more readily available to plants, such as nitrate, ammonium, biologically available phosphorus, and soluble potassium, calcium, and magnesium.  

When applying worm castings to the garden or house plants, they should be used sparingly as they are much more concentrated than regular compost. Mix 1 part worm compost to 4 parts potting soil to use as fertilizer or side dress your plants with a small spoonful (for smaller plants) or handful (for mid-sized plants). It is helpful to gently mix the worm castings into the soil rather than just spreading it on top.