Vermicomposting sounds complicated, but the basic idea is surprisingly simple: worms help transform certain food scraps and bedding materials into a rich soil amendment called vermicompost or worm castings.
It can be done indoors, requires very little space, and—when the bin is properly maintained—shouldn’t create bad odors or attract pests.
On Episode 133 of The Arner Adventures Podcast, we talked with worm advocate and educator Cathy Nesbitt about vermicomposting, worm farming, and how beginners can start composting with worms at home.
Cathy founded Cathy’s Crawly Composters, an environmental business she started in 2002. She has spent years helping people understand that worms aren’t gross little garden intruders. They’re tiny members of a very effective food-scrap cleanup crew.
What Is Vermicomposting?
Vermicomposting, also called worm composting, uses composting worms to break down food scraps and other organic materials.
As the worms consume these materials, they produce castings. You can use the finished vermicompost as a soil amendment for gardens, container plants, flower beds, and houseplants.
Unlike a traditional outdoor compost pile, a worm bin:
- Can be kept indoors
- Requires very little space
- Does not need to heat up
- Uses specific composting worms
- Can work well for apartments and small homes
- Primarily handles food scraps and bedding materials
According to the Environmental Protection Agency’s home-composting guide, vermicomposting can be done indoors or outdoors with a bin, bedding, appropriate worms, and food scraps.
Vermicomposting vs. Traditional Composting
Traditional composting relies primarily on microorganisms, moisture, oxygen, and a balance of carbon-rich and nitrogen-rich materials. An outdoor compost pile may also heat up as the materials decompose.
Vermicomposting relies on composting worms and the microorganisms living within the bin. A worm bin should remain at a moderate temperature because excessive heat or cold can harm the worms.
A traditional compost pile may be a good option if you have a yard and need to process leaves, grass clippings, and larger amounts of organic material.
A worm bin may be a better fit if:
- You live in an apartment
- You have limited outdoor space
- You primarily want to compost kitchen scraps
- You want to compost throughout the winter
- You prefer a small indoor system
- You want worm castings for houseplants or a garden
You can also use both methods if you produce enough compostable material.
Listen to the episode here:
Benefits of Vermicomposting
Vermicomposting gives food scraps another purpose instead of placing them in the trash.
Potential benefits include:
- Reducing the amount of household waste you throw away
- Producing a useful soil amendment
- Composting in a small space
- Composting indoors throughout the year
- Supporting healthier soil
- Helping soil retain moisture and nutrients
- Reducing the need to purchase some gardening products
- Learning more about natural decomposition
A worm bin can also be a fun educational project for adults and children. It provides a close-up look at what happens to organic materials after we stop considering them useful.
What Kind of Worms Do You Need?
Not every earthworm is suitable for a compost bin.
The most commonly recommended composting worm is the red wiggler, scientifically known as Eisenia fetida. Red wigglers naturally live near the surface of decomposing organic material and can process food scraps efficiently.
The EPA advises against collecting random earthworms from your yard or purchasing an unidentified species from a bait shop. Some earthworms need different living conditions, and invasive species may be mistakenly sold under other names.
Purchase composting worms from a reputable worm grower or ask an experienced local worm-bin owner whether they have worms to share.
What You Need to Start Vermicomposting
You do not need an elaborate setup to begin. A basic worm-composting system requires:
- A ventilated worm bin with a lid
- Red wiggler worms
- Moist bedding
- A small amount of soil or finished compost
- Appropriate food scraps
- A location protected from extreme temperatures
- Extra dry bedding for routine maintenance
You can buy a premade system, such as a stackable worm-composter station, or create a basic bin using plastic storage containers.
If you make your own bin, it needs ventilation so the worms can breathe and a way to prevent excessive liquid from collecting around them.
The EPA’s indoor worm-bin instructions provide measurements and directions for creating a simple system with plastic bins.
How to Start a Worm Bin
1. Choose the right location
A worm bin can be placed in a basement, laundry room, garage, closet, under a sink, or another protected location.
The EPA recommends maintaining a worm-bin temperature of approximately 59°F to 77°F. An outdoor bin should remain shaded and protected from freezing temperatures and excessive heat.
Choose somewhere that is:
- Easy to access
- Protected from direct sunlight
- Away from heating vents
- Safe from freezing
- Safe from curious pets
- Convenient enough that you will actually use it
2. Prepare the bedding
Worm bedding helps maintain moisture, airflow, and a comfortable living environment.
Possible bedding materials include:
- Shredded non-glossy newspaper
- Shredded office paper
- Torn cardboard without wax or tape
- Paper egg cartons
- Dry leaves
Soak or dampen the bedding and wring out the excess water. It should feel like a damp sponge rather than dripping wet.
Fluff the bedding inside the bin so air can circulate. Fill roughly half the container and add a small handful of untreated soil or finished compost.
3. Add the worms
Place the composting worms on top of the prepared bedding. They will usually move away from the light and settle into the material on their own.
Give them some time to adjust before adding a large amount of food. Beginning with a small quantity makes it easier to learn how quickly your worms process scraps.
4. Add food scraps gradually
Bury a small amount of food beneath the bedding rather than leaving it exposed on top.
Covering food discourages fruit flies and helps control odors. Place the food in one area of the bin so you can check whether it has been consumed before adding more.
Overfeeding is one of the most common beginner mistakes. Add more food only after most of the previous scraps have broken down.
5. Monitor moisture and airflow
The bedding should remain damp but never waterlogged.
If the bin becomes too wet, add dry shredded paper or cardboard. If it becomes too dry, lightly mist the bedding with water.
Avoid packing the contents down. Worms and the microorganisms within the bin need oxygen.
What Can You Feed Composting Worms?
Composting worms can process many common kitchen scraps, including:
- Fruit scraps
- Vegetable scraps
- Coffee grounds
- Paper coffee filters
- Paper tea bags without staples
- Crushed eggshells
- Small amounts of plain grains
- Small pieces of uncoated paper or cardboard
Chopping scraps into smaller pieces can help them break down faster.
Freezing and thawing food scraps before adding them can also soften the material, although this is optional.
Pay attention to what disappears quickly and what remains untouched. Your particular worm colony may process some materials faster than others.
What Should You Keep Out of a Worm Bin?
Avoid adding:
- Meat
- Fish
- Bones
- Dairy products
- Fats, oils, and greasy food
- Pet waste or cat litter
- Plastic produce stickers
- Plastic-lined tea bags
- Glossy or coated paper
- Large quantities of onions or garlic
- Large quantities of citrus
- Anything treated with pesticides or other harmful chemicals
Meat, dairy, and greasy foods can create odors and attract pests. Strongly acidic or odorous scraps may also create unpleasant conditions when added in large amounts.
When in doubt, leave it out until you can confirm that it is safe for the worms.
Does Vermicomposting Smell?
A healthy worm bin should have little odor. When opened, it may smell earthy, similar to damp soil.
A strong or unpleasant smell usually indicates a maintenance problem rather than an unavoidable part of worm farming.
Common causes include:
- Adding more food than the worms can process
- Leaving food exposed
- Excess moisture
- Poor airflow
- Adding meat, dairy, or greasy foods
- Allowing uneaten scraps to accumulate
If the bin smells bad, stop feeding temporarily, remove rotting food, gently loosen compacted bedding, and add dry shredded paper or cardboard.
Common Worm-Bin Problems
Fruit flies
Fruit flies are often attracted to exposed food.
Bury scraps under several inches of bedding, keep the lid closed, and avoid overfeeding. Freezing scraps before adding them may help prevent fruit-fly eggs from entering the bin.
A bin that is too wet
Add dry bedding and gently fluff the contents to improve airflow. Reduce foods with very high water content until conditions improve.
A bin that is too dry
Lightly mist the bedding and cover it with additional damp paper. Do not pour a large amount of water directly into the bin.
Worms trying to escape
A few worms exploring the lid is not necessarily a crisis. Large numbers trying to leave may indicate extreme temperatures, excessive moisture, poor airflow, or unsuitable food.
Check the conditions and correct the likely issue before adding more scraps.
Food isn’t disappearing
The worms may have more food than they can process. Stop feeding temporarily and wait until most of the existing scraps have broken down.
Chopping food into smaller pieces can also speed up the process.
How to Harvest Worm Castings
Worm castings are generally ready when the contents look dark, crumbly, and soil-like, with relatively few recognizable food scraps.
Depending on the system and conditions, it may take several months to produce enough vermicompost to harvest.
One simple harvesting method is to feed the worms on only one side of the bin for a couple of weeks. As the worms move toward the food, you can collect finished castings from the other side.
Another method is to place small piles of vermicompost under a bright light. The worms will move away from the light and toward the bottom, allowing you to remove the castings from the top gradually.
Return the worms and any unfinished material to the bin with fresh bedding.
How to Use Vermicompost
Finished worm castings can be:
- Mixed into potting soil
- Added to garden beds
- Sprinkled around established plants
- Added to containers and window boxes
- Used when transplanting seedlings
- Spread lightly across lawn or garden soil
Worm castings are concentrated, so you generally do not need to replace all of a plant’s soil with vermicompost. Mix a small amount with existing soil or use it as a light top dressing.
More About Cathy Nesbitt
Cathy Nesbitt is a worm advocate, educator, speaker, and the founder of Cathy’s Crawly Composters, established in 2002.
Her goal is to help people see food scraps as a resource while making vermicomposting feel approachable—even for those who initially want nothing to do with worms.
Cathy also founded Cathy’s Sprouters and Cathy’s Laughter Club. Her work connects sustainability, gardening, healthy living, community, and laughter.
When she isn’t talking about worms, sprouts, or laughter, Cathy enjoys cycling and gardening.
Our Conversation With Cathy Nesbitt
In Episode 133 of The Arner Adventures Podcast, we discuss:
- How Cathy became interested in worm farming
- Why she started Cathy’s Crawly Composters
- The basic process of vermicomposting
- How worm composting can reduce household food waste
- Common misconceptions about keeping worms
- Whether a properly maintained worm bin smells
- What beginners need to start vermicomposting
- The most rewarding parts of Cathy’s work
- Her advice for anyone hesitant about worms
- Cathy’s answers to our Fast Five questions
- What a life well-lived means to Cathy
Vermicomposting Resources
- Cathy’s Crawly Composters
- EPA Guide to Creating and Maintaining an Indoor Worm Bin
- EPA Guide to Composting at Home
- Find a Worm Dealer
- 5-Tray Worm Composter Station
- Our Composting Posts
- The Arner Adventures Podcast Sponsors
FAQs | Frequently Asked Questions
Yes. A basic worm bin requires only a ventilated container, moist bedding, composting worms, food scraps, and a suitable location. The main beginner rule is to start with less food than you think you need and monitor how quickly it disappears.
Yes. You can keep a properly maintained worm bin in a basement, laundry room, closet, garage, or under a sink. It should be protected from extreme temperatures and should not produce a strong odor.
No. Ordinary garden earthworms usually require different living conditions. Red wigglers are one of the most widely used species for vermicomposting. Purchase them from a reputable grower or obtain them from an established worm-bin owner.
