Worm Composting

Worm Composting There are a number of good reasons to consider giving indoor worm composting, also known as vermiculture, a try this year:

1. Worm composting is relatively easy; while it may appear to be somewhat mysterious, it’s really quite simple. (If you already have an outdoor compost pile or bin that is built directly on the ground, you probably have benefitted from the great work that worms can do in converting food scraps to compost.)

2. It’s very inexpensive – in fact, you might be able to get started with what you already have around you. More on this later.

3. It’s ecologically sound – you can significantly reduce, or perhaps eliminate, the amount of kitchen waste that you’d put into the trash stream. And, you might eliminate the need to make trips to the outdoor compost pile during the winter.

4. You’ll make more great compost for your gardens.

Getting Started – Here’s what you’ll need:

1. A container, tray, and a cover

You’ll need a good container for your industrious little worms. You can easily build a wood container or two, or you can purchase stackable plastic containers from many garden catalogs and web sites. Wood is somewhat preferable, as it will absorb some moisture; but, plastic containers can work quite well, also.

You worm farm container should be 8 inches to 12 inches deep; the size of the container should be based on how comfortably you will be able to lift it when it is filled with worms and compost. For most of us, a container with two square feet of surface (1 foot wide by 2 feet long, or a square measuring about 1 ft. 5 inches on each side) area will work well.

If the bottom of the container is completely solid, drill about 12 holes (one quarter to one-half inch in diameter) to allow for draining and aeration. If you’re building your container with 1″ by 4″ or 1″ by 6″ lumber, leave a small space between the floor boards for drainage and aeration.

Assuming that your worm container is indoors (in the basement or a heated garage) you should set your container on bricks or blocks to that any excess moisture can drain into a tray. This prevents the container from becoming too wet and mucky, which is not a good environment for worm composting.

Of course, the tray should be slightly larger than the outside dimensions of the box that house your worms. If you’re going to build your own box or boxes, you may want to start your project by procuring a tray or two, and then building the boxes to fit the trays.

Plastic trays will last a lot longer, weigh less, and are easier to clean. Trays can be obtained from catalogs, web sites, hardware stores, pet stores, or home supply stores. You can also buy or use and old metal cooking tray, so long as it has sides that are about an inch high. Or, a kitty litter tray could get you started.

You’ll also need a cover for each container, which will provide the dark environment that worms like and also help the bedding retain moisture. The cover can be a solid piece of wood or plastic, a piece of thick burlap, or a dark plastic sheet. If you choose to do worm composting outside, a solid wood or plastic cover is necessary to keep the bedding from becoming too wet when it rains.

2. Bedding for your little buddies

Worm CompostingThe best bedding for your worms is a mixture of ground-up dry leaves, straw, and either a small amount of compost from your compost pile, or a little bit of garden soil. Adding compost or garden soil will add microorganisms that will also help the compost production. The bedding should be very loose, so that you can easily move it by hand when adding your kitchen scraps.

While a lot of people recommend using shredded newspaper for bedding, we suggest that you should only use that as a last resort, as some of the chemicals in newsprint may not be the best things to add to your compost pile or garden. The bedding should be moist, but not saturated. If the bedding becomes too moist, add a little bit of sawdust to absorb excess water.

3. Worms

Worm composting requires red wigglers – not dew worms or earth worms. You can find these smaller worms in fist-size clumps in an active compost pile or in decomposing manure (if you live on or near a farm), or you can buy them from a number of mail order sources, which typically sell them in lots of 1,000. For each pound of food scraps that you add per day, you should have about two pounds (or 2,000) of worms. Red wigglers will quickly reproduce in the right environment, and you may soon want to add an additional container.

4. Food

The best foods for worm composting are vegetable and fruit scraps, pulverized egg shells, and coffee grounds. Don’t add meat or fish scraps, dairy products, or oily foods to your worm composter because they will create unpleasant odors and, if your worm composting is done outside, those foods will be more likely to attract flies and other pests.

Bury the food in the bedding and cover it. Scoop a hole in the bedding with your hand, insert the food scraps, and cover the food with clean bedding. The worms and microorganisms will find it and quickly convert it to nutrient rich worm castings and compost.

If you’re concerned that you don’t have enough food for your worm population, you can supplement their feeding with bread crumbs.

5. The Right Environment

Your composter should be in an area where the temperature is between 40 and 80 degrees Fahrenheit. If your worm composter is in a basement or unheated garage, you can provide heat with an inexpensive heating cable if the air temperature drops below 40 degrees. Place the cable in the bottom of the box and cover it with a thin piece of Styrofoam. The heating cable should have a built-in thermostat that maintains a setting of about 70 degrees.

Tools You’ll Need

After you’ve built or bought a an open bin or closed bin composter, there are only a few tools that you’ll need to make compost. If you’re already a gardener, you probably already have the tools that you need.

Is it working?

Worm CompostingYour worm composter is working if the worm population looks healthy and the bedding gradually disappears and is replaced with sweet smelling compost.


When most or all of the original bedding has been converted to compost, move the compost to one side of the container and add new bedding and food to the other side of the container. The worms will gradually migrate to the new bedding and food, allowing you to remove the finished compost without removing any or many of the worms. Your worm compost can be stored in plastic buckets or trash containers for later use, added to your outdoor compost, or added directly to the garden.



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