Worm composting at home

Urban Worm Girl, Amber Gribben, was at Living La Vida Verde a couple of week s ago. For those of you who missed it, though, there’s still plenty of information on vermiculture (aka worm composting) out there.

One organization, the NYC Compost Project, sponsored by the New York City Department of Sanitation, suggests an inexpensive way to compost if you have limited space.

How to Make a Worm Composting Bin (reposted from the NYC Compost Project)

1. CONSTRUCT THE WORM BIN

The size of the bin you need is determined by two factors—how much space you have and the amount of food scraps your family

courtesy of NYC Compost Project

produces. Two pounds of worms (about 2,000 worms) should be able to process about a pound of food scraps a day. A surface area of one square foot is needed for each pound of worms.

Here, we adapt a plastic storage bin that is easy to find in many stores around the city. You could also use or make a wooden box. Just make sure the box is shallow (8 to 12 inches deep) and that it has a lid to keep conditions dark and moist.

Drill at least 10 quarter-inch holes in the top and around the top of the sides of the bin for air circulation.

2.    MAKE THE BEDDING MATERIAL

courtesy of NYC Compost Project

Your worms will require about 8 inches of bedding material, such as leaves, potting soil, or one-inch strips of newspaper. Bedding should be at a moisture level equivalent to a wrung-out sponge.

Here we are starting a bin with newspaper. Shred the newspaper length-wise into long, one-inch strips and then soak the strips in a bucket of water to make them damp.

3.   WASH KITCHEN SCRAPS

Before you add any fruit or vegetable waste, take the time to scrub the skins before placing them in the bin. This will wash off any fruit fly eggs that already might be present and will greatly reduce your risk of fruit fly infestations.

4.   ADD KITCHEN SCRAPS

The best materials to add to a worm bin are washed fruit and vegetable scraps, coffee grounds and filters, tea bags (remove the staples—they harm the worms' stomachs!), egg shells, paper napkins and towels, and dead plants and flowers. Remember to feed worms a varied diet and don't overload the bin with fruit, or you'll attract fruit flies.

Do not feed your worms meat, fish, or dairy products. These items will produce odors and attract flies as they decompose. It is generally not a good idea to feed your worms leftovers, even if they do not include fish or meat, since they also tend to produce odors and attract fruit flies. In general, try experimenting with what works in your bin and what doesn't—but be advised that once your bin has a fruit fly problem, it's hard to get rid of!

5. ADD WORMS

You will want to add red worms (Eisenia fetida or Lumbricus rubellus) to your bin. Don't use nightcrawlers or other garden

courtesy of NYC Compost Project

worms, which are usually brown or gray in color. (Contact the "Rotline" sponsored by the Chicago Home Composting Program of the University of Illinois at (773) 265-9587 for a list of suppliers.)

6.   COVER THE FOOD SCRAPS

Bury the food scraps well underneath the newspaper or other bedding material you are using. Do not leave food scraps exposed on top of the bin.

7.    KEEP THE BEDDING MATERIAL MOIST

Worms need a dark, moist environment in order to thrive. Especially if you are using a naturally dry bedding material such as shredded newspaper or fall leaves, be sure to keep the bedding material moist.

You can use a plant mister like the one shown here to occasionally moisten the bedding material.

8. HARVEST YOUR WORM BIN

When the bedding starts to resemble dark, crumbly soil (usually in one to four months), it's time to harvest your compost.

Move all the bedding over to one side of the worm bin. Add new, dampened bedding to the empty side, and start placing food scraps on that side. Over about a one month period, most of the worms should move over to the new bedding, allowing you to scoop out the relatively worm-free compost. Finished worm compost (vermicompost) starts becoming toxic to the worms if it's left in the worm bin for too long. (An alternative harvesting method is presented here.)

Just a few notes before you commence your composting adventure:

While you don’t necessarily need a garden or plants to compost, you still should know where your compost is going. The Green Lantern environmental column of Slate Magazine suggests checking if any of your friends, community or school gardens, or even people in ad-sections or ad-sites such as Craigslist need compost.

Make sure you’re willing to put in the upkeep. A properly cared for worm composting bin will have little smell, healthy worms, and few pests. Urban Worm Girl, the NYC Compost Project, and the Chicago Home Composting Program have troubleshooting sections  and other resources on their websites.

Happy composting!