Worm composting is a great way for anyone with limited space to turn kitchen waste into compost for the garden or houseplants.
Composting food scraps with worms, known as vermicomposting or vermiculture, has its advantages because it takes so little space and it takes very little work to make the best fertilizer. A can of rich, crumbly compost can be produced in just eight to twelve weeks.
In this article:
What is Worm Compost?
The common earthworm is not the kind used to produce the rich organic waste known as worm compost.The type most commonly used are red wigglers also called brandling worms or manure worms.
They reproduce quickly in the confines of a worm bin. Start out with at least 1,000 worms (18 oz) in weight. The most cost effective way to acquire them is by extracting them from a maturing compost pile, or a manure stack. The easiest way is to purchase them by mail order or over the Internet.
Worm Compost Bins
Worm compost bins can be purchased, or a wooden crate, boxes, or a plastic storage bin will suffice at no cost. The bin should have a relatively large surface area, and there’s no need to worry about the worms escaping.
Good drainage is the main requirement since kitchen waste can produce a lot of moisture (worm liquid) and the worms will drown if conditions are too wet. If the bin will not need to be moved, a bin without a bottom such as a beehive compost bin set directly on the ground and covered will work. If there isn’t access to one, they are easy to make.
Location of the Worm Bin
Worms should be kept at temperatures between 50 and 77 degrees Fahrenheit. Anything lower will slow down the composting process. However, the worms can survive at lower temperatures.
Keep the temperature constant and out of direct sunlight during the summer. In the winter, bring the bin into a garage or warm greenhouse, or insulate it well before the cold weather starts.
Worms cannot process large quantities of food (kitchen and vegetable scraps) at once. Excess food will spoil before they can process it, resulting in an unpleasant smell. The worms will not process rotten food and may die.
Add no more than 3–4 quarts of food at a time. Build up the feeding gradually to get an idea of how much they will eat. The worm bin can survive many weeks without food being added so don’t add extra food before going away on vacation.
What to Put in the Worm Bin
The same ingredients that go into a regular compost bin may go into a worm compost bin:
- Vegetable peelings
- Vegetable crop waste
- Fruit peelings
- Cooked leftovers
- Shredded paper, paper bags
- Paper towels
- Coffee grounds
- Tea leaves
- Onion skins
- Egg cartons
As with regular composting, these items should never go into a worm compost bin:
- Large amounts of citrus peel
- Dairy products
- Meat and fish
- Cat/dog feces
- Purchased flowers
How to use Worm Compost
Worm compost is more like a concentrated fertilizer than a bulky organic compost. It’s rich in humus, and has good water-holding capacity. These are just some of the ways to use it:
- A top dressing to squash and other fruiting vegetables during the growing season
- A top dressing for patio pots or house plants
- An enrichment to commercial potting mix and as a water-holding component for hanging baskets
- An ingredient in homemade potting mixes and other growing media
Organic compost such as worm compost is a means to provide high-fertility to garden soil. Worms can be bought over the Internet. It’s possible to find them in a manure stack or compost pile. However, ordering is probably an easier more pleasant way of acquiring them.
Set Up a Worm Composter
Two plastic garbage cans (15 or 30 gallon) will provide the space needed for the average household to start worm composting. Galvanized steel cans may be used but plastic will not get as hot and may be preferable in warmer climates.
The cans must first be aerated on the bottom, sides and top by punching or drilling small holes. The holes should not be larger than a No. 6A nail and the container must have a cover.
The holes allow excess water to drain; too much water drives out oxygen and suffocates the worms. The holes should be cleaned when the compost is emptied from the can.
Start Worm Composting
To begin composting, start with about 500 red wiggler worms (lumbricus rubellus). These worms (deep maroon in color) are not the same as those found in the garden. Red wiggler worms thrive only in manure or garbage and are rarely found in ordinary garden soils.
To start the cans for compost, do it in layers. Begin with four inches of garden soil on the bottom, followed by three inches of kitchen garbage (no meat products). Add a cup of bone meal, a three-inch layer of dead leaves, shredded paper, straw or hay, then more kitchen waste, and a layer of chicken or cow manure. Next, put in two inches of soil and add the worms.
Continue adding kitchen waste and layering as needed until the can is full. Always end with worms and garden soil in order to exclude flies and prevent maggots.
Start a new can in about six weeks. It takes about 12 weeks for the compost to be ready to harvest.
Harvest Compost and Worms
To separate the worms from the can, take advantage of the worms’ distaste for light. Start by emptying the can in a pile on a worktable or plastic. Shine a floodlight over the pile and the worms will retreat to the center of the pile.
Scrape the worm-free soil from the top and sides of the pile. Repeat until all that is left is a wriggling mass of worms to be used for the next can.
The resulting compost is a good top dressing for the garden or can be used as a boost for houseplants.
Precautions in Worm Composting
The worms will not survive if the compost freezes. Put the can in a warm place for the winter to prevent freezing. Continue layering the can throughout the winter months so it can be used in the spring.
Do not add milk or meat products, fat, bones or items with pesticides. Banana and orange peels should be used minimally. Chop kitchen scraps into small pieces to speed up the composting.
Beneficial and Easy
Worm composting will provide a regular supply of compost all year-round with very little effort. The worms multiply rapidly and can be used to start a second can, which ensures a continual supply of compost. The red wigglers can also be added to the outdoor compost bin to speed up that process.
Commercial worm bins are available at most garden centers but making one at home can is fun, easy and will save money.