Build your own worm composting bin

Supplement to “Cooking Up Compost”

Bluegrass PRIDE provides these instructions for making and using a vermiculture compost bin for either inside or outside.

How to make an inside vermiculture compost bin
Chris Muesing, environmental educator with Bluegrass PRIDE, offers the following tips for an inside vermiculture compost bin:

1. A simple plastic container with holes in the lid and a few worms inside can be kept under the sink—perfect for use in a small house or apartment setting.

2. Transfer compost and some worms to a larger bin outside as needed. If bin is located outside, the worms will hibernate over the winter. But in extreme cold or heat bring inside, such as in a garage.

3. Avoid using citrus fruits, bread, onions, or any other food with a high sugar, acid, or carbohydrate content in the compost container. Doing so will slow the composting process and negatively affect its quality.

4. Use raw, uncooked fruit and vegetable scraps in the compost container—even salad can be used if the dressing and nonvegetable toppings are rinsed off first.

5. Cover any food with shredded or ripped paper to prevent fruit fly invasion.

6. Harvesting the compost can be done in the early spring before planting a garden or flower bed. Simply separate the worms from the bin and till the finished compost into the selected garden space or inside planters. The worms can be used again in the same bin. You can also take some of the worms and release them into your selected planting space.

How to make an outside vermiculture compost bin

Source: Bluegrass PRIDE, Composting Manual for Schools.

Materials
Two 10-gallon plastic tubs
One 10-gallon plastic tub lid
Drill and 3/16-inch drill bit
Brick or three small rocks
A few cups of soil from outside—not bagged soil
Shredded paper
Red wigglers (30-100 worms), available at bait shops
Spray bottle
Trowel

For a two-bin system for vermicomposting, begin with a small 10-gallon bin. Drill a row of holes along the top edge of the bin and about 10 holes in the bottom. Then drill several holes in one of the lids.

Take the second bin and put several rocks inside. Then take the other bin with the holes drilled in it and place on top of the rocks in the second bin. The rocks will prop the inside bin up and allow any extra moisture to drain and collect at the bottom.

Next, take the soil, shredded paper, and a few food scraps and put them into the bin, arranging the materials in a pile in the center of the bin. Cover any food with paper, which is important to prevent fruit flies or the smell of food from coming in contact with the air.

Put the worms in the bin. Soon the worms will start disappearing into the paper and center pile. Leave the lid off until all the worms disappear into the center pile. Then spray the pile with water until all the paper is moist, but not wet. Check the bin every few days and add paper and water slowly as needed and add food sparingly. Food scraps can be added every couple of weeks.

Food scraps to add: Banana peels, apple cores, vegetable scraps, egg shells, and coffee grounds (paper filters too).

Food scraps NOT to add: Citrus: oranges, lemons, etc.; meat, milk, and fats/oils.

Over time the worms will make small brownish material called worm castings, which will need to be harvested once the bin is about half full of these castings.

Use a tarp and spread out the contents of the bin, including the worms, separating the worms from the material.

Then restart a new bin using the worms and a small amount of worm castings. The separated castings are great to use mixed into the existing soil of an outside garden or into the soil of inside and outside planters. Any liquid from the bottom of the second bin is called “compost tea,” and can be diluted with water and used on inside plants.

To read the Kentucky Living March 2012 feature that goes along with this supplement, go to Cooking Up Compost.