An indoor worm bin keeps you composting after the outdoor pile freezes. Start with a stacking tray bin, moist shredded bedding such as coconut coir and newspaper, and about a pound of red wiggler composting worms (not garden earthworms), keep the bin somewhere between roughly 55 and 77°F, and bury small amounts of chopped fruit and vegetable scraps under the bedding. Set up correctly, a worm bin has no foul smell and produces rich castings for houseplants and seed starting.
What you need
- A bin. Stacking tray systems make harvesting easy because worms migrate up into new trays. A plastic tote with air holes drilled near the top and in the lid also works.
- Bedding. Rehydrated coconut coir mixed with shredded newspaper or brown cardboard. Avoid glossy paper.
- Worms. Red wigglers (Eisenia fetida) live in the top layer of decaying material and eat fast. Earthworms from the garden burrow deep and do poorly in bins.
- A handful of garden soil or finished compost to introduce microbes, plus some crushed eggshell for grit.
🌱 Get Personalized Plant Picks
Answer a few quick questions and we’ll match plants to your exact yard conditions.
Find My Plants →Setting it up
- Soak a coir brick in water until it expands, then mix with shredded paper.
- Squeeze the bedding until it feels like a wrung-out sponge. Too wet is the most common failure.
- Fill the bottom tray 4 to 6 inches deep and fluff it loosely.
- Add the worms on top and leave the lid on and a light on in the room. They will move down into the bedding within an hour.
- Wait a few days before the first feeding.
Shop worm composting supplies on Amazon
Stacking worm bins, live red wiggler composting worms, and compressed coconut coir bricks for bedding. We may earn a commission at no extra cost to you.
Amazon · Worm composting bin Amazon · Red wiggler worms Amazon · Coconut coir brick
Where to put it
A basement, laundry room, pantry, or under a kitchen sink all work. Keep it away from heaters and out of unheated garages that drop near freezing. Worms slow down below about 55°F and suffer above about 80°F.
Feeding
- Good foods: vegetable peels, fruit scraps, coffee grounds and paper filters, tea leaves, crushed eggshells, and small amounts of cooked plain grains.
- Skip: meat, fish, dairy, oily or salty food, large amounts of citrus or onion, and pet waste.
- Chop scraps small and bury them under an inch of bedding in a different spot each time.
- Start slowly. Feed a cup or two of scraps a week at first. Once the bin is established, a pound of worms can process up to roughly half its weight in food a day, but most bins run best a bit below that.
- If food is still sitting there at the next feeding, wait.
Fixing common problems
| Problem | Likely cause | Fix |
|---|---|---|
| Sour or rotten smell | Overfeeding or too wet | Stop feeding a week, add dry shredded paper |
| Fruit flies | Exposed food | Bury scraps deeper, cover with a sheet of dry newspaper |
| Worms crowding the lid | Too wet or too acidic | Add dry bedding and crushed eggshell, open the vents |
| Worms dying or sluggish | Too cold, too hot, or too dry | Move the bin, mist the bedding |
Small gnats around a bin are often fungus gnats from wet bedding. Drier bedding and buried food fix it; our guide to fungus gnats in houseplants covers the same life cycle.
Harvesting castings
After about three to four months, the bottom tray turns dark, crumbly, and earthy. In a stacking system, start feeding only in the top tray for a few weeks so worms move up, then remove the bottom tray. In a single tote, push finished material to one side and feed on the other.
Mix castings into potting mix at about 10 to 20 percent for houseplants, sprinkle a thin layer on top of pots, or blend into a raised bed soil refresh in spring. Castings are mild and will not burn roots.
Basic hygiene
Wash your hands after handling bedding or castings, and keep the bin closed where pets cannot dig into it.
Bottom line
A tray bin, damp coir bedding, and a pound of red wigglers turn kitchen scraps into castings all winter with very little effort. Keep it moist but not wet, bury food, and feed less than you think. Come spring, move larger volumes back to an outdoor compost tumbler.
Related reading
Ready to match plants to your location? Try the PlantWise Plant Finder →