Learn with the Worm!

Teacher Resources - Environmental School Activities and Curriculum

Worm composting or vermicomposting is a perfect illustration of "natural" recycling. Worms eat food scraps, leaving behind dark castings (i.e. worm manure) called vermicompost. Vermicompost is a nitrogen-rich natural fertilizer that commercial worm farms have found to be very profitable.

Steps to successful vermicomposting include Set Up, Worm Adoption, and Maintenance.

I. Set-Up

Like all living creatures, worms need food, water, air and shelter. Set up is simply creation of the worm ecosystem, which includes a bin, bedding, and food.

Bin

You can purchase commercially made bins or construct a bin from wood or plastic. A bin just needs to be 12"-18" deep, have a snug fitting lid and small holes in the bottom or sides for ventilation.

The ideal bin for first time vermicomposters is an eighteen-gallon plastic tote, with a tight fitting lid (12" to 18" tall, 12" x 24" base). Drill air holes (no bigger than 1/4 inch) about halfway up on the sides of the bin.

Location, Location, Location

Worms prefer temperatures of 65-85 degrees F. Keep your worm bin indoors, out of the sun, in a quiet place, but not so isolated your class forgets about them!

Bedding

Worms love to live under moist paper or leaves. Bedding keeps the worms damp and also provides a high carbon material that the worms will break down. Tear newspapers into one-inch strips, fluff them up, and then moisten them so they are as damp as a wrung-out sponge. Fill your bin 3/4" full with this moist "bedding." Sprinkle bedding with a few handfuls of soil. Shredded leaves, paper, cardboard or straw are also good bedding materials.

Food

Worms eat about half their body weight a day! Feed 1 pound of worms about a cup of good scraps per day.

Food scraps include: apple

Fruit and vegetable peelings, cores, seeds

Breads, cereals, macaroni

Coffee grounds, paper napkins

NO Meats, Fat, or Dairy (worms will consume these foods, but you run the risk of a very smelly bin!)

Always bury food at least 4" down under the bedding. If the bin starts to smell or food isn't breaking down quickly, give your worms a break and feed them less food. Worms reproduce quickly, so they should be able to eat all your food if there's enough space and you increase the amount of gradually. Hint: wrap food scraps in moistened newspaper. It reduces chances of developing fruit fly problems and adds fresh bedding at each feeding.

Feed in a pattern, choosing a spot and rotate around the bin. Rotation provides excellent observation activities. How many days until the worms find the new food and to completely eat all the food in one location?

II. Worm Adoption

Your mini-ecosystem is ready. Where do you get the worms? For vermicomposting, the red wiggler or Eisenia fetida is the preferred species. These worms are "composter" worms, capable of processing large amounts of organic material. They thrive in the fluffy layer of leaves on the forest floor and in manure piles.

Soil dwellers, earthworms or night crawlers, thrive in earth tunnels and won't be happy in the confined space of a vermicompost bin with the constant interruption of waste additions and observation by students.

happy worm

Red wigglers can be purchased at local bait shops or via the Internet. The bait shop owner may call red wigglers manure worms or red hybrid. Start your bin with about a pound of worms (1,000-2,000 worms). When the worms arrive, just place them on top of the bedding. Leave the bin exposed to light as the worms work their way down in to the bedding. Once all the worms have left the surface, bury their first meal, cover with the lid and leave them alone for a week or so to allow them to get used to their new home. Then begin their regular feeding schedule.

III. Maintenance

A healthy worm bin is a productive worm bin! Keep your worms healthy and happy by:

• Adding fresh bedding every 2-3 weeks, keeping a 4" to 6" layer of fresh bedding over the worms and food in your bin.

• Keep bedding moist, like a wrung-out sponge. Add dry bedding to absorb excess moisture.

• Harvest worm castings periodically every 3 - 6 months.

Worms, like all creatures prefer not to live in their own waste. After about 6 weeks, there will be noticeable changes in the bedding. It will be darker, and you will see more castings than bedding. It is time to harvest the vermicompost.

The Harvest

The simplest way to harvest the worm castings is to move the contents of your bin to one side. Fill the empty side with fresh damp bedding and a small handful of soil. Feed only on the new side and the worms will eventually migrate to the fresh side.

Use the castings by sprinkling 1/2 " to 1" layer on top of indoor or outdoor plants or just dig the castings into your garden soil.