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Vermicomposting & Vermiculture - Orange County

About two-thirds of the waste stream is made up of organic materials, including paper and food waste. While paper can often be recycled, food waste has fewer useful disposal options besides composting. One effective method is vermicomposting, which uses worms to recycle kitchen scraps. 

 

This method is simple, reduces rotting waste, and complements traditional backyard composting by handling food waste efficiently. Together, a worm bin for food and a compost bin for yard waste can help households divert most organic waste from landfills. With just a few key components and simple instructions, vermicomposting can be easily established in nearly any home in Orange County.  

 

What is vermicomposting? Vermiculture? 

Both of these words are derived from vermi, the Latin word for worm. The two terms – vermiculture and vermicomposting – while distinct, are closely connected: vermiculture involves breeding and raising earthworms in an environment that supports their growth and reproduction. Vermicompostingis the process of using these worms to break down organic waste into nutrient-rich compost, known as vermicompost.

Vermicomposting is the process of using worms to decompose vegetable matter. The resulting worm compost or worm castings (worm manure) is a nutrient rich soil amendment, which improves soil structure, fertility, and water-holding capacity. Worm castings are considered by many horticultural experts to be the best soil amendment available. Nutrients in vermicompost are often much higher than traditional compost and are in a form that makes them readily available to plants. The nutrient content of castings depends on the material fed to the worms–and worms are fed materials with high nutrient content, such as food waste. The biology of the worm's gut facilitates the growth of fungus and bacteria that are beneficial to plant growth. 

Ready to get started?  The essential components of a home vermicomposting unit are an aerated container (worm bin), some moist bedding, food scraps, and a few thousand red worms or red wigglers (Eisenia foetida).

Worm Bin -- Structure 

Worm bins can either be purchased or made at home using materials like wood or plastic. Buy a commercial vermicomposting bin from a garden center or online or make your own using items on hand. Repurposed containers such as old shipping crates, wooden boxes, opaque plastic storage bins, large suitcases, or even abandoned bathtubs can all serve as effective worm bins. To stay eco-friendly, consider reusing materials or building your bin from scrap lumber.  A simple plastic storage container from a hardware store works well if modified properly. Drill ¼-inch holes in the bottom for drainage and along the sides for ventilation. Avoid adding holes in the lid to prevent excess moisture during rainy weather. Worms thrive in darkness, so be sure to secure a lid to keep light out and to deter pests like rodents. Two sources for building a bin are Building a Worm Bin the Easy Way and Easy DIY Worm Bin.

Worm Bin – Size, Temperature, and Location

Worms will eat about one pound of food waste for each square foot of surface area per week. The amount of food waste generated will determine the size of the bin. As a general guideline, provide at least two square feet of surface area for every household member. Voracious vegetable eaters may need a bin with four square feet of surface area per person. Size depends on how much food waste is to be composted, but the ideal depth should be between eight and twelve inches —no deeper than 20 inches. Bins need to be shallow because the worms feed in the top layers of the bedding. A bin that is too deep is not as efficient and could potentially become an odor problem. 

Ideally a worm compost bin should be located in areas where the temperatures are between 55˚F to 77˚F.  Temperatures outside this range will slow the process; extreme temperatures will kill the worms. Maintain adequate moisture and ventilation for best results.

Place the bin in a location protected from extreme temperatures—out of direct sunlight, in a shady area, and if possible, beneath a roof or overhang that will also provide some weather protection. Some options for bin locations are a shady deck or patio, beneath an outdoor potting table, or in a garage, garden shed, or basement.  If the covered bin is placed in a shady area with at least six inches of moist bedding material, it should be just fine outdoors year-round in most Orange County climates. Also make sure that the worms are sheltered from excessive rain since they require oxygen and can easily drown.  Another consideration: worms do not like a lot of noise or vibrations. Keep them away from high traffic areas.    

 Bedding Material

Before ordering worms, create a habitat for them, a worm bin filled with appropriate bedding material and placed in an environment that will keep them healthy and eager to eat those food scraps. Bedding serves to hold moisture, bury food, and is an additional food source.

Start by adding moist bedding—things like shredded paper, dead leaves and other materials high in carbon, mimicking the worms' natural habitat of decaying organic matter, such as the moist piles of decaying leaves or manure where they are commonly found. Bedding material used in the worm bin should provide worms with a similar comfortable moist environment. Decaying leaves (no pine, redwood, bay, or eucalyptus) or well- rotted and rinsed horse manure.

Other common bedding materials that can be used including shredded black and white newspaper, sawdust, straw, hay, wood chips, cardboard, burlap coffee sacks, peat moss, decaying leaves, and coconut fiber available at nurseries. Consider using a combination of these materials to avoid matting and restricted air flow. A caution about cardboard: It cannot be used if it contains wax or plastic, which include cereal boxes, and other boxes designed to hold food items. Avoid using glossy paper from newspapers and magazines, junk mail and shredded paper from offices, because those may contain toxins. Also no bleached or printer paper or paper with colored ink. Bedding should make up at least 50% of the organic matter.

Bedding is the living medium for the worms so it should be light, fluffy and non-toxic,  

but it is also a food source, so it should be moist and loose to enable the earthworms to breathe and to facilitate aerobic decomposition. Put at least six inches of bedding material in the bin and moisten and mix so the material is evenly damp—like a wrung-out sponge. Squeezing a handful of properly moistened bedding material should produce only a few drops of water between fingers. The bin is now ready for the worms and the kitchen scraps.

Worms

Red worms or red wigglers (Eisenia fetida) are the most common worms used for vermicomposting as they have desirable features: they consume organic material quickly, reproduce well, prefer to live near the surface and do not burrow. Found naturally in old piles of manure, or in decaying leaves beneath trees, this worm species is different than the common earthworms or nightcrawlers that live under the soil surface. They are active, have big appetites. and can eat more than half their weight in food every day. Because they thrive and reproduce quickly in the confined environment of a well-maintained worm bin, they are also the worm most raised and sold as fish bait. They are available at bait stores or online. Below is a list of Worm Suppliers in and around Orange County. The number of worms needed will depend on the container size. Note: earthworms are not good composters.

Feeding The Worms

Mary Appelhof, author of “Worms Eat My Garbage” recommends two pounds of worms—about 2,000 wigglers—for every pound per day of food waste. To figure out how much food waste is generated, monitor it for a week and divide by seven.   

Best advice? Start Slowly. It will take time for bacteria to develop and the bin can quickly become very smelly if too much food is added, too fast.  Some vermiculture experts advise starting with a smaller number of worms. Worms can reproduce rapidly under ideal conditions, potentially doubling their population every 60-90 days. They are hermaphrodites and can mate every 7-10 days, with each mating resulting in cocoons that hatch into baby worms.

Reduce the amount of food scraps put in the bin, until the population increases. One pound of redworms will easily take care of each half pound of garbage. To add worms to the bin, scatter them over the top. The skin on the worm reacts to light and they will immediately work their way down into the bedding to get away from the light.

Worms will eat a wide variety of organic materials such as paper, manure, fruit and vegetable waste, grains, coffee grounds, and ground yard wastes. Fortunately they like to eat many of the same foods humans eat. They also handle rotting and moldy food scraps not fit for human consumption. But for safety and sanitary reasons, and to avoid unwanted pests in the worm bin, certain food items should not be placed in the bin.

While worms will eat meat and dairy products, it is best not to feed these materials or oily foods to worms, due to potential odor and pest problems. Since worms have no teeth, any food they eat must be small enough to swallow, or soft enough for them to bite. Some foods may not be soft enough initially for them to consume, but they quickly degrade so that the worms can consume them. Worms have a gizzard like chickens so fine grit should be added to help the worms digest food. Gritty material includes cornmeal, coffee grounds and/or finely crushed egg shells (dry the shells and then crush). If the bin becomes odorous, cut back on the amount of food or try chopping the food up into smaller pieces.

Do Feed Worms  

  • Fruit and vegetable scraps
  • Grains
  • Coffee grounds
  • Paper
  • Manure
  • Yard waste (ground or finely chopped)
  • Vegetable scraps                  
  • Fruit rinds and peels (keep citrus to a minimum)                
  • Bread and grains                
  • Pasta                      
  • Coffee grounds and filters          
  • Tea bags                        
  • Food waste
  • Crushed eggshells (rinsed) for a source of calcium                
  • Shells left intact and avocado skins provide a place where worms will hide together
  • They also handle moldy or rotting food that’s no longer edible for humans.  

Don’t Feed Worms

  • Meat, bones  
  • Fish
  • Dairy products (cheese, butter, etc.)
  • Oils, oily foods, peanut butter
  • Spicy food, chili, onion, garlic
  • Garden trimmings
  • Pet waste and cat litter
  • Avoid too much citrus
  • Anything that could attract pests or create strong odors

Worms don’t have teeth, so food must be soft or broken into small pieces. Though some items may be too tough at first, they will degrade over time. To aid digestion, add fine grit to the bin—such as cornmeal, coffee grounds, or crushed eggshells (dry them first).

By starting slowly and managing food input, your worm bin can grow into a healthy, odor-free composting system.

Initial Set Up, Care and Maintenance

  • Place moistened bedding in worm bin. Bedding should squeeze out a few drops when squeezed in the palm of the hand. Fill bin 80% with bedding.
  • Scatter the red wiggler worms on top of the bedding. They do not like light and within minutes will work their way down.
  • Distribute small food scraps underneath the bedding and close the lid. Feed worms every 5-7 days.
  • Do not overfeed or the vegetable matter will rot. Remove excess or rotting food.
  • At each feeding, check that the bedding is still moist and add new bedding as needed.
  • Worms do best when disturbed as little as possible. It is not necessary to provide care daily or to turn the compost.
  • Covering the food and bedding with cardboard assists in keeping the bin dark and cool.
  • Excess moisture will collect in the bottom of the bin. Remove this worm tea as it accumulates. It is full of nutrients and can be used to fertilize the plants.
  • In the summer months, temperatures above 86˚Fwill be harmful to the worms. Keep the bin in the shade, bring it indoors, or cover with a damp blanket.
  • In the winter months when temperatures drop below 40˚F, insulate the lid, place bales of straw around it, or bring indoors. At freezing, the worms will die.
  • With proper care, worms will actively reproduce.
Harvesting Worm Castings (Vermicompost)

Worm castings can be harvested every two and a half to every six months, depending on how many worms there are and how much they consume. Once the bin is established, it requires minimal attention until the bedding becomes unrecognizable, and the contents are mostly dark, earthy-looking compost. Over time, worms will not only consume food scraps but also break down their bedding into rich, crumbly vermicompost. When the material becomes dense and compact—no longer an ideal environment for worms—it’s time to harvest the castings and refresh the bin with new bedding. No method removes all worms from the compost, but the goal is to recover enough to restart your bin. Here are two common approaches:

Method 1: Manual Sorting (Best for Small Bins or with Kids)

Dump the contents of the bin onto a large plastic sheet or tarp. In bright sunlight, form the compost into small mounds. Worms, sensitive to light and heat, will burrow toward the center of each pile. After about 15 minutes, gently scrape off the outer layers of compost (now worm-free). Repeat until all that remains is the worm-rich center. Set aside a small amount of compost to mix with new bedding, then return the worms to the bin. Kids often enjoy this hands-on method. Be sure everyone wears gloves.

Method 2: Migration Method (Less Labor-Intensive)

Push all contents (worms, food, bedding, compost) to one side of the bin. Add fresh bedding and food to the empty side. Over the next few days, worms will migrate to the new food source. Once they move, you can harvest the compost from the other side. Remove any remaining food scraps or large undecomposed pieces. Mix a small amount of compost into fresh bedding, then return the worms. Worms naturally move upward and toward loose bedding and fresh food. The denser compost settles at the bottom, making separation easier.

After Harvesting, mix some old compost into new bedding to retain helpful microbes, return worms to the refreshed bin and restart the composting cycle. Regular harvesting keeps the worm bin healthy and productive while providing nutrient-rich castings for the garden or houseplants.

Tips for Maintaining a Healthy Worm Bin

  • Start slowly by feeding the worms small portions - a quart or less of food scraps per week. As the worm population increases and other biological activity speeds up in the bin, they will eat more.
  • Do not over-feed the worms. Too much food in the bin may create an acidic unhealthy environment for the worms and cause odors. Before feeding look to see if most of the food from the previous feeding has been eaten.
  • Always cover food scraps with bedding material that is already in the bin, or by adding new bedding on top of the food. Exposed food will draw fruit flies and other unwanted pests.
  • Maintain bedding as moist as a wrung-out sponge. Plastic bins tend to accumulate moisture and will need dry bedding added to absorb excess moisture. For convenience keep a bucket or bag of dry shredded newspaper or sawdust next to the worm bin. Wooden bins tend to dry out and need additional water occasionally.
  • Be sure to allow at least 3 inches of space between the top of the bedding material and the lid of the bin to ensure that the worms receive enough fresh air to breathe.
  • Monitor the worm bin frequently at first until a good feeding rate and a stable moisture level is established.

Troubleshooting The Worm Bin LOREN, this is supposed to be a table…. I did it both ways…table and anchored left.. 

PROBLEM: Bin attracts flies
CAUSE: Food is exposed
REMEDY: Bury food completely, feed less fruit

PROBLEM: Worm bin smells bad
CAUSE: Too wet or too much food
REMEDY: Check drainage holes/ aeration, add dry material, feed less, smaller pieces

PROBLEM: Worms dying
CAUSE: Too much food in bin, too dry
REMEDY: Feed less or get a larger bin, add water to maintain dampness

PROBLEM: Bin attracts ants
CAUSE: Too dry
REMEDY: Add water to maintain dampness

How to Use Vermicompost and Compost Tea

Once harvested, this gardener’s magic—worm castings—can be used in a variety of ways throughout the garden. Rich in beneficial microbes and nutrients, castings make an excellent natural fertilizer. They can be mixed into garden soil or gently worked in as a top dressing for both indoor and outdoor plants. To amend potting soil, combine four parts potting mix with one part worm compost. Castings are also ideal for seed-starting mixes, flower beds, around shrubs, roses, and vegetables. Another popular method is compost tea: mix 1 part worm castings with 3 parts non-chlorinated water. Let the mixture steep overnight, stirring every 5 to 7 hours to keep it aerated. The tea can be applied directly to plant beds or diluted—4 ounces of concentrate per gallon of water—for use as a foliar spray.

Because worm castings are highly concentrated, a little goes a long way. Store any unused castings in a cool, dry place, covered and out of direct sunlight to preserve moisture and microbial life. When properly stored, they can remain effective for 12 to 18 months.

 Further Reading/Resources

References