Compost with Red Worms
Indoors or Out

Red worms eat a lot—one half their body weight per day—of your kitchen’s vegetable waste. They leave behind “castings,” a very nutrient rich, earth smelling material that is power food for all plant life.

All you need to get started inexpensively is:

The best worms to use are Eisenia Foetida red wrigglers. They live from 2-4 years and multiply quickly, with a 45 day hatch time.

You need twice as many worms, by weight, as you have food scraps per day—a 2:1 ratio. For example, if you produce 1/2 pound of food scraps per day, you’ll need 1 pound of worms to start. If you don’t own a scale, put your day’s or week’s scraps into a zip lock baggie and weigh it at the grocery store.

After 2-3 months you should have an optimal population of 100,000 red worms. Red worms make good fish bait, so feel free to use some.

Setting Up the Worm Compost Box

To do it yourself, a box with a lid made of a washable material like plastic or metal is best. Provide air holes. Generally, one square foot or area is needed for each pound of scraps composted per week. For 2 people a 1’x2’x2’ (4 sq.ft. = 4 lbs/wk scraps) container is good. For 4-6 people, use a 1’x2’x3’ box (6 sq. ft. = 6 lbs/wk scraps).

There are also very good red worms composting “hotels” available on the market. These are generally multi-level systems of stackable trays with perforated bottoms. When the worms digest all the food scraps in the lowest tray, they migrate up to the next tray, permitting you to then remove the rich castings left behind in the lower tray.

Place your worm compost box out of direct sun in an area where the temperature will remain between 55 F/13 C to 80 F/27 C. Temperatures above 85 F/29 C will kill the worms.

The best bedding materials are non-colored corrugated cardboard, newsprint, computer paper, or newspaper. Shred each into 1/4-1/2” strips. The bedding should be wet enough so that when squeezed, 2-3 drops of water come out. Simply soak it in a container of water for a few minutes and then squeeze it out. Maintain this level of moisture by spraying or sprinkling water periodically, as needed.

Spread the bedding to a depth of 1 1/2”, and then sprinkle in a few handfuls of dirt. This helps the worms digest. Though it varies with the size and activity of your worm composting system, the bedding should last 4-6 months.

How Much Food Waste to Add

Remember to keep the ratio of worms by weight to food waste per day at 2:1. An overloaded system can become anaerobic and smelly. If this happens, just stop adding more waste and allow the worms to catch up.

Once you add the worms to the bedding, they will burrow to the bottom, as they do not like light. You should add your food scraps by burying it into the bedding at different locations around the box. The worms may not immediately seek out the new food, as they like to let bacteria break it down a bit first.

What Types of Scraps Can You Add?

Your food scraps must be biodegradable and not meat or dairy. Fruits, vegetables, crushed egg shells, tea bags and coffee grounds are great. You may also add shredded dry leaves or grass clippings.

Harvesting the Worm Compost

You will notice after a few weeks that the bedding will go down and that it will become darker. The amount of worm castings will increase. Since too many castings can be harmful to the worms, it is then time to remove them. Besides, you want them for your plants and garden!

You can do this in two ways. You can push the old bedding to one side of the box, add new bedding to the other side, and place new scraps only in the new side. The worms will migrate to the new side eventually, and you can then remove the old bedding and castings.

Or, you can dump the entire box contents onto a cut open cardboard box or other convenient material. If you do this in a lighted area, the worms will burrow down to avoid the light. You may then scoop off the top layer of castings and bedding. The worms will burrow yet deeper. You then scoop off the next top most layer. And so on.

To sort the castings from the old bedding, try drilling 1/4” holes in the bottom of an old cake pan or plastic box. The castings should fall through leaving the bedding behind to discard. Or buy a commercially available worm compost sifter.

How Much Care Do Red Worms Need?

If you provide the proper temperature, moist bedding level and food source, red worms need no care. In fact, they like to be left alone. If you want to observe them, do so under dim light. When they die, they decay quickly without harm to your composting system.

If you go away on vacation, feed them beforehand. If you stay away for more than two weeks, it is a good idea to have a friend come by to add food scraps and to check the bedding moisture level.

In a successful worm compost system, you may find that you eventually have too many worms. If this happens, you can start a second box or convince your friends to try it.

The castings are 10-20 times higher in microbial activity than typical soil, which improves the fertility of any soil to which it is added. It also adds enzymes to the soil and improves its physical structure.

Blend the castings into your garden soil. You also may sprinkle castings at the base of a plant and then water. Or make a tea from castings by soaking them in water for a day or two, then pouring this into house plant containers.

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