How to Make Worm Compost Bins

Worm compost bins (or wormeries) can be a fun, educational project for the entire family. Wormeries produce rich compost for use in gardens from fruit and vegetable scraps that you would otherwise throw away. This project is fairly simple and results in a basic worm compost bin.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• 2x4 lumber - 16 pieces that are all 18 inches long.
• Four pieces of 2 foot by 2 foot metal screen (1/4 inch holes are ideal).
• Nails or wood screws.
• One piece of plywood (2 ft by 2 ft).
• Worms
• Soil
• Food scraps (fruit or vegetable only).

1. Cut your 2x4 lumber into 16 equal length sections. Using 18 inch sections result in a wormery that is roughly 18 inches by 18 inches. Anything larger can be a problem because of the weight of the soil mixture that rests on the bottom of each tray.

2. Nail or screw four of the 2x4 sections together to make a square tray frame. Wood screws will provide a stronger bond. If you wish to make the wormery stronger, you can use corner brackets (L-shaped metal brackets) to strength each corner. Repeat this step to make four square trays.

3. Cut sections of the metal screen or mesh to a size that fits all the way to the outer edges of the square frames. Attach one piece of the screen to the under side of each frame, using metal construction staples or small nails that you can bend over into the wood. The weight of the soil and scraps will push the screen down, so fasten it every inch or so.

4. Cut one piece of plywood (1/2 inch thick is ideal) to a size that is at least 2 inches larger that the square trays on all sides. You may wish to cover the plywood with a layer of thick plastic sheeting to lengthen the life of the plywood, but if you do so, make sure that water does not pool on top of the plastic sheeting.

5. Place moist (not wet) soil to near the top of each tray. Add earth worms (either dug up in your yard or purchased) in one of the trays. Next, add fruit or vegetable scraps (ideally, you should chop them into very small pieces) to the tray with the worms and the adjoining trays. Do not add too much food waste, because the worms will have a limited capacity.

6. Stack the trays with the tray with the worms in one of the middle positions which will allow the worms to work their way up or down to adjoining trays. After the worms convert all of the food scraps in a tray and move to another tray, you can use the soil-compost mixture in your garden and refill the tray with new soil and food scraps. Then, move tray that the worms are in to one of the middle positions.

Tips & Warnings

• Make sure that you keep the soil in all trays loose and slightly moist. The worms will not be able to move through the soil if it is too wet or dry or if it is blocky.
• If you wish to leave your wormery outside, put it in a protected location away from direct sunlight. The heat from direct sunlight will dry out the soil and harm the worms.
• Cover the top tray to keep rain out of the wormery. If the soil becomes dry, lightly water it so that you can control the amount of moisture.
• Do not use soil that is filled with fertilizers in your wormery. This is often bad for the worms and reduces their ability to work through the scraps.
• It is important to fill each tray all the way to the top so that when the trays are stacked, it results in an almost continuous column of soil that the worms can move through.
• If you keep your wormery outside, you may wish to raise the plywood base with bricks to keep out any running water.
• Do not add meat or dairy food scraps to your wormery. These items will not work and will begin to smell rotten.
• Do not add more than a cup or two of chopped up scraps. Worms can only eat through so much food, and the remainder will rot and become moldy. You will learn how much your worms can eat and adjust the input accordingly.
• If you live in an area with animals such as raccoons, be careful where you place your wormery. Raccoons may smell the food scraps and dig into the wormery.