Vermicomposting uses composting worms to recycle kitchen, garden, and specific household wastes into a powerful bio-fertilizer. This process takes place in the “wormery”. Wormeries can be purchased or made with simple, easy to find components.
The end product of the wormery is called “worm castings”. Worm castings are the manure produced through the worm's digestion process. Castings are a rich source of nutrients and microbes for the landscape, edible garden, and containers.
Why Vermicomposting?
Not all gardeners are able to build a compost pile. Physical limitations, space limitations, deed restrictions, schedule, amount of available waste – any number of things may limit a gardener’s ability to compost. However, ANY homeowner can vermicompost, even if they don’t have a large garden.
A small worm bin can be placed under a sink, in a spot in the utility room, or in a cool spot in the garage. Larger operations can be located in a shady spot in the garden. Children love feeding the worms so you may find plenty of volunteers for this daily chore.
What are the benefits of Vermicompost?
- Extracts toxins and harmful fungi and bacteria from the soil.
- Stimulates the development of micro-flora populations in the soil.
- Increases water retention of the soil.
- Stimulates plant growth, even at low concentrations.
A bit about the worms
Garden worms are all members of the Soil Food Web. They are in the group of macro-organisms. But compost worms are not earthworms. They share the same physical attributes, but they have a very different lifestyle.
There are three basic families of garden worms. To have a successful vermicomposting bin, and happy, healthy worms, you need the right kind. Before we get to the VERY simple process of building a household worm bin, here are a few interesting facts about worms.
Earthworm Facts
Terrestrial earthworms fall into two categories – endogeic, shallow burrowers (by comparison), and anecic, the deep burrowers. There are about 2,700 types of earthworms.
Earthworms come in many sizes. There is even one from South America that can reach 8 feet in length and weigh over a pound. The largest reported is a South African species that has been measured in at 22 feet, but they average 8 feet in length. Night Crawlers are a common earthworm that is used for fishing. They can burrow up to six feet below the ground.
In just one acre there can be a million or more earthworms. This million earthworms can eat 10 tons of organic matter a year and turn over 40 tons of soil as they tunnel to move from place to place. These tunnels help air move into the soil, which is good for plants.
Earthworms recycle leaves, fruits, branches, and bark that have fallen to the ground. They recycle dead plants and grass clippings from your garden and lawn. They even recycle the manure from larger animals such as livestock or your dog or cat.
Burrowing, terrestrial worms are adapted to live in the soil, and would not make good compost worms for an enclosed bin. However, night crawlers will find their way into an outdoor compost bin. These worms prefer a cooler environment. When the pile heats up they will retreat to the shelter of the ground, but when the pile cools down they will take advantage of all that moist organic matter located all in one place.
Compost Worm Facts
Compost worms prefer to live in the first few inches of leaf litter, and do not burrow deeply into the soil. They are in the third group – epigeic. Epigeic worms are closely associated with human activities, such as residing in a manure pile. A favored species of compost worm is the Red Wiggler.
Compost worms love all kinds of waste that humans create – we call it “garbage”, earthworms call it “supper”. Compost worms will take your old bread crusts, eggshells, coffee grounds, apple cores, paper towels, banana peels, and lettuce leaves and turn them into compost. When they have finished recycling, they leave us with worm castings, which are rich with valuable nutrients. These nutrients are one of the components that provide us with fertile soil.
So how do they do all this recycling?
Pharynx: The worm pushes its pharynx, or throat, out of its mouth to grab a particle and to pull it back into its mouth where it gets it nice and wet with saliva.
Esophagus: Once the particle is good and wet, it is pushed down the esophagus, then into the crop.
Crop: The crop is a storage compartment for food and other things the worm swallows. From the crop, the particle passes to the gizzard.
Gizzard: The gizzard is where the work happens. The worm uses tiny stones that it has swallowed and the strong muscles of the gizzard to grind up the particle. These muscles and the stones work together almost like teeth.
Intestine: Once the particle has been all ground up it moves to the intestine where the digestive juices break it down even more.
Bloodstream: Now that the particle is digested, some of it will pass into the bloodstream to nourish the worm. Whatever is leftover is excreted. The excreted leftovers are called worm castings.
Worms breathe through their skin. They keep themselves moist with a layer of mucous which helps them breathe. Worms do not have eyes, but they have organs that help them sense light and feel vibrations in the ground. Worms have five ”hearts” - actually a heart-like organ called an aortic arch. They can crawl forwards or backwards. They hold on to the earth with bristles, and use their muscles to push themselves along.
Alien Invaders?
Most people will be surprised to learn that the earthworms we see in our gardens are not an indigenous species. We now consider them a sign of garden health; that we are maintaining an adequate level of organic material. And we consider them an essential soil builder, but they are a very recent addition to our ecosystem.
It is thought that the majority of North American earthworms were killed off in the last ice age. Canadian and American scientists have come to the conclusion that very few species were left, and only in un-glaciated areas. The remaining species were not very successful in repopulating the continent.
Virtually all of the earthworms we see today have European or Asian origins. The common night crawler came to America with its earliest settlers, the colonists at Jamestown. These earthworms were very successful and have spread across the nation.
The fact that they are non-native is particularly concerning for the northern forests where the common earthworm is considered an invasive pest. They are destroying the duff; the litter that comprises the forest floor. The forest depends on a bio-geochemical cycle that is upset by the invasive night crawler. The duff is meant to maintain a specific mass and the worms are depleting that mass too quickly.
Here on the Gulf Coast, where a lot of material is consumed relatively quickly in our semi-tropical climate, the night crawler has little negative impact. In fact, they are responsible for a great deal of soil improvement.
Raising Composting Worms at Home
You will need:
- (2) Plastic storage bins with lids. They can be any color except clear because earthworms need a dark environment.
- Newspaper (or other suitable bedding)
- Water
- Compost Worms (Red Wigglers
- Kitchen waste
Preparing the bins
Place the first bin on your work surface. This bin will catch any excess moisture (leachate) that is produced by your worms as they recycle your garbage into compost.
The second bin is where your worms will live. Turn the second bin over, and drill 20 – 30 ¼” diameter holes in the bottom to allow the excess moisture to drain into the first bin. Set the second bin into the first bin. Drill additional ventilation holes in the top of the bin if necessary. Your bin needs good airflow. Cover any exposed holes with screen to prevent fruit flies and other pests from interfering with your wormery.
Preparing the bedding
Tear newspaper into long strips about ½ to 1 inches wide. Place these in the top bin and moisten them with water. They should be damp, but not dripping wet. This will be the bedding for the worms.
Place the damp strips of paper into the worm bin. You will need a minimum of 3 inches of loose bedding, but it is best to fill the bin ½ to 2/3 full. Do not add water after the first set-up. The worms will produce their own moisture and will derive water from the food scraps.
Introducing the worms
You can purchase compost worms from local worm raisers, on the internet, or by mail order. Be sure you ask for composting worms. Some worms need to burrow in the soil and they will not be happy in a worm bin. Your worms will come in a bag, box or can. Just gently shake them into your prepared worm bin.
Once you have added your worms, put the lid on the worm bin. Make sure you have air holes poked in the top IF your bin appears to be airtight. Many of the plastic bins available for storage have relatively loose fitting lids, and no holes are necessary.
Feeding your worms
After your worms are settled in their new home, they will need to be fed. Begin adding small amounts of kitchen scraps each day. Do not add more than they seem to be eating. They particularly like coffee grounds, egg shells (crush them up before adding them), fruit peels, vegetable peels. You can even add small amounts of bread.
Do not feed meats, grease, or oils. Do not feed banana peels, unless they are organic. Feed only a few citrus peels at one time, and stay clear of the onion family. Adding a tablespoon or two of damp play sand will give them material to fill their crop which is a part of their digestive system.
A pound of worms will eat about a pound of waste per day. If you notice a lot of mold forming, you are overloading your bin, just back off until that matter is cleared up. It will not harm the worms – just let them catch up.
Taking care of the wormery
Worms are livestock, and must be cared for properly. Compost worms do not like excessive heat, and will not survive freezing temperatures. They are best cared for indoors. If we are comfortable, they are comfortable. If you must keep a bin outdoors, it should never be in direct sun, and should be brought indoors when any frost is expected.
Monitor the moisture. The bedding should remain moist, but should never be soggy. If there is excessive moisture in the bottom of the bin, add more bedding and check your drainage holes.
Harvesting the castings
You will notice that your bin may start to get full of castings - castings look like crumbly coffee grounds – and you will want to harvest. There are several ways to harvest.
- Upward migration - Add a new worm bin on top of the first, making sure the holes in the bottom are smooth and large enough for the worms to crawl through. Prepare it the same way you did the first one, with bedding. Start putting the worm food in the second bin, and the worms will eventually move to the top bin. After they do, remove the first worm bin and use the castings.
- Horizontal migration - Push the contents of the bin to one side. Place new bedding and food on the empty side. In a few weeks, the worms will have migrated to the newly prepared side allowing you to harvest the castings.
- Pile & scrape - Turn the contents of the entire bin out on a dampened tarp or plastic sheet, under bright light. Pile it up high in the middle and wait a while. The worms will migrate down to the damp lower layer to get away from the light and you can scrape the castings off the top. Return the worms to a newly prepared bin.
How to use the castings
- Containers – mix a few handfuls of castings into your potting soil before you plant. The castings are non-burning, so there is no need to worry about measuring or using too much. You can use up to 25% castings for lush, healthy growth.
- Vegetable beds – mix a handful of castings into the soil before planting transplants or seeds.
- Garden Soil – sprinkle a few handfuls of castings around your plants and lightly work it into the soil. Water in, and cover with mulch.
- Liquid Fertilizer – add one cup of castings to a gallon of water. Stir and let it steep for a week. This makes and excellent liquid plant food or foliar spray.