What You Need to Begin Worm Composting

Worm composting (also called vermicomposting) breaks down food scraps and paper into rich soil using red wiggler worms in a contained bin. Unlike outdoor compost piles, worm bins work indoors or in a garage, take up about as much space as a storage container, and produce finished compost in three to six months instead of a year or more. The worms do the work—you just feed them and keep conditions right.

You will need four things to start: a bin, worms, bedding material, and food scraps. A basic bin can be a plastic storage container with drainage holes drilled in the bottom, or you can buy a ready-made worm bin (brands like Worm Factory and Rubbermaid make stackable versions). The bin should be at least 12 inches deep and hold roughly 1 gallon of space per pound of food scraps you add each week. If your household produces 2 pounds of scraps weekly, a 20-gallon bin is a reasonable starting size.

Key Takeaways

  • Red wiggler worms are the only species that work for indoor composting; they cost $25 to $50 per pound and you need about 1 pound to start a small bin.
  • Bedding (shredded newspaper, cardboard, or coconut coir) must be moist but not soggy, and should fill half the bin before you add worms.
  • Feed worms once a week by burying food scraps under the bedding; they eat fruit and vegetable waste but not meat, dairy, or oils.
  • The bin should stay between 55 and 77 degrees Fahrenheit, which is why most people keep them indoors or in a basement rather than outside.
  • Finished compost (dark, crumbly, and smelling like soil) is ready to harvest after three to six months, depending on how often you feed the worms.

Choosing and Setting Up Your Bin

A worm bin does not need to be fancy. A 20-gallon plastic storage container works as well as a $200 commercial bin. Drill or cut 12 to 16 small holes (about 1/4 inch) in the bottom for drainage, and 8 to 10 holes near the top of each side for air. If the bin sits on a shelf or table, place a tray or old baking sheet underneath to catch any liquid that drains out—this liquid, called worm tea, can be diluted with water and used on houseplants.

Fill the bin halfway with bedding material. Shredded newspaper (black and white only, not glossy ads), cardboard, or coconut coir all work. Avoid glossy paper and colored inks. Soak the bedding in water until it is as moist as a wrung-out sponge, then squeeze out excess water and fluff it into the bin. The bedding should feel damp but not waterlogged. Add a small handful of soil or finished compost from a garden to introduce microorganisms that help break down food.

Place the bin in a location where the temperature stays between 55 and 77 degrees Fahrenheit. A basement, garage, or closet works well. Avoid direct sunlight and heat sources. Worms slow down or die if it gets too cold or too hot, so an unheated shed in winter or an attic in summer is not ideal.

Buying and Adding Your Worms

You need red wiggler worms (scientific name Eisenia fetida)—not earthworms from your garden, which burrow deep and do not compost well in bins. Red wigglers are smaller, reddish-brown, and stay near the surface where food is. They cost $25 to $50 per pound depending on where you buy them. Online suppliers like Uncle Jim's Worm Farm and local garden centers often carry them. One pound of worms (roughly 1,000 individuals) is enough to start a 20-gallon bin.

When the worms arrive, open the bag and let them rest in the bedding for a few hours before you feed them. They may seem sluggish at first—this is normal after shipping. Bury them gently under the damp bedding and leave the bin undisturbed for three to five days. During this time, the worms will adjust to their new home and spread throughout the bedding. Do not feed them yet.

Feeding Your Worms the Right Way

After the first week, begin feeding your worms once per week. Bury food scraps 4 to 6 inches under the bedding in a different spot each week, rotating around the bin. This prevents the food from piling up in one place and keeps the bin from getting too wet or smelly. Worms eat fruit and vegetable scraps, coffee grounds and filters, tea bags, crushed eggshells, and shredded paper or cardboard. Chop large pieces into chunks smaller than a walnut so they break down faster.

Do not add meat, fish, dairy, oils, fats, or pet waste. These attract pests and create odors. Avoid onions, garlic, and citrus in large amounts—small amounts are fine, but too much can upset the worm population. Bread and grains can go in, but use them sparingly because they attract fruit flies. A good rule: if you would not eat it raw, do not put it in the bin.

Feed only as much as the worms can eat in one week. If you see uneaten food after seven days, you are feeding too much. Scale back and wait until the previous batch is mostly gone before adding more. Overfeeding is the most common mistake and leads to a wet, smelly bin and mold growth.

Keeping Conditions Right

A healthy worm bin should smell like soil or a forest floor, not like rotting garbage. If it smells bad, the bin is too wet or you are feeding too much. Stop feeding for two weeks and leave the lid off to let it dry out. If the bin is dry and the worms are clumped together, add water by misting the bedding with a spray bottle until it feels like a wrung-out sponge again.

Check the bin once a week when you feed. Look for worms near the surface (a good sign they are active), and watch for mold or fruit flies. A little white mold is normal and harmless—the worms will eat it. If you see fruit flies, bury food deeper and cover it with a layer of bedding or cardboard to block access. Make sure the bin has air holes and is not sealed completely, or the worms will suffocate.

The bin should stay moist but never waterlogged. If liquid pools at the bottom, drill more drainage holes or add dry bedding material. If the top layer dries out, mist it lightly. The moisture level is right when you can squeeze the bedding and get just one or two drops of water.

Harvesting Your Finished Compost

After three to six months, the original bedding will have turned dark and crumbly and will smell like rich soil. This is finished compost. The worms will have moved to the top layers where fresh food is, so most of them will be out of the way when you harvest. Spread the contents of the bin on a newspaper or tarp in a well-lit area. Worms avoid light, so they will burrow down into the pile. Scoop off the top layer of compost (which still has worms in it) and set it aside. Repeat until you have separated most of the worms from the finished compost.

Put the worms and any remaining bedding back into the cleaned bin with fresh bedding, and you are ready to start again. Use the finished compost in houseplant pots, garden beds, or give it to friends. It is dark, crumbly, and full of nutrients that plants love.

Troubleshooting Common Problems

If your worms are trying to escape by crawling up the sides of the bin, the conditions inside are wrong—usually too wet, too dry, or the food is rotting. Check moisture first: squeeze the bedding and adjust with water or dry material. Then check that you are not overfeeding. If the bin smells sour or like ammonia, stop feeding for two weeks and increase air flow by opening the lid or drilling more holes.

Fruit flies are attracted by exposed food. Always bury scraps under bedding and cover them with cardboard or more bedding. If flies are already present, stop feeding for a week and let the worms eat down the existing food. You can also place a piece of cardboard or newspaper over the top layer to block flies from laying eggs.

If worms are dying or the population is shrinking, the bin is likely too hot, too cold, or too acidic from overfeeding. Move the bin to a cooler spot if needed, and stop feeding until conditions improve. A small number of dead worms is normal, but if you see many, something needs to change.

Frequently Asked Questions

Can I keep a worm bin outside in winter?

Red wigglers slow down or die below 55 degrees Fahrenheit, so outdoor bins in cold climates need insulation or should be moved indoors for winter. In mild climates where temperatures stay above 50 degrees, an outdoor bin works year-round. A garage or basement is the easiest solution for most people.

How long does it really take to get usable compost?

Three to six months is typical, depending on how often you feed and how warm the bin stays. Warmer bins (around 70 degrees) work faster than cool ones. You will see dark, finished material at the bottom after two months, but waiting until month four or five gives you more compost to harvest.

What do I do if I go on vacation?

Worms can go two to three weeks without food. Before you leave, feed them well and make sure the bin is moist. They will eat the food slowly while you are away. When you return, resume your normal feeding schedule.

Can I use garden soil instead of buying worms?

No. Garden soil contains earthworms and other creatures, but not red wigglers. Earthworms burrow deep and do not stay in a bin. You need to buy red wigglers specifically—they are the only species that composts well in a contained space.

Is worm compost better than regular compost?

Worm compost is richer in nutrients and beneficial microorganisms than regular compost, so plants often grow better with it. But both work well for gardens and houseplants. The main advantage of worm composting is that it works indoors and produces compost faster.