Indoor Composting with Worms

Betsy Dudash
April 7, 2022

Why compost?

  • Reduce waste going into landfills. As food waste rots in a landfill, it produces methane, one of the top three greenhouse gases. Methane is 28x more effective at trapping heat than carbon dioxide.
  • Turn kitchen scraps and yard and garden waste into rich organic matter and fertilizer for yards, gardens, and planters.
  • Improve the health of your soil. When used as a soil amendment, compost supports microbial activity, suppresses plant disease, helps the soil to retain essential nutrients and water, reduces soil compaction and improves aeration, and makes the soil more fertile.

How much space do you need?

  • Your worm bin will need at least 6-9 sq. ft. in a dark, quiet, climate-controlled space such as a basement, attached garage, or closet. Keep it away from the washer and dryer, though.

If you have a compost bin or barrel, why would you need a worm bin?

  • You can compost with worms year-round. Traditional compost methods stop working during the winter.
  • With a barrel composter you need to stop adding material at some point so it can finish decomposing. Your worms have to be fed regularly or they’ll die.
  • You can harvest vermicompost (aka humus) in just 2 months; even a well-functioning bin can take 5 months to produce finished compost. 


What’s the deal with Red Wigglers?

  • Red Wigglers (Eisenia fetida) are tolerant of a range of conditions, from +/-55-80° F.
  • They are prolific breeders.
  • Unlike earthworms, they live near the surface, in the litter, instead of burrowing deep. This makes it easier to harvest the worm castings, AKA black gold.
  • They’re not scaredy-worms and don’t mind being bothered occasionally.

Choose a bin and make preparations

  • Home-made or purchased? 
  • The size depends on the amount of food waste you produce.
  • Needs to allow for ease of access, have proper ventilation, and have good drainage.
  • Get the worm bedding ready: shred papers, newspapers, or cardboard or gather some dry leaves. These should be lightly moistened before you add the worms.
  • Start saving your kitchen scraps in containers with lids. 
  • Time to order those red wigglers (1,000 should do) or get some from a friend!

What to feed your wigglers

  • Include coffee grounds, used tea leaves (but not the strings or staples), vegetable peels, apple cores, fruits and vegetables (but not citrus, tomatoes, onions, or garlic)—anything that’s easily digestible for your worms.
  • Don’t give them pepper, tomato, or tomatillo seeds.
  • We keep a container by the coffeemaker for used coffee grounds and tea leaves and a container under the kitchen sink for food scraps.
  • Put a layer of shredded paper or newspaper on top of their food.
  • Don’t give them corn cobs or husks, avocado pits or rinds, or anything that’s too hard, woody, or fibrous for them to eat. Also don’t feed them meat, dairy, grease, etc.

Keeping your wigglers happy

  • Don’t fret about feeding them too little—check on them every few days or weekly and give them about 1” of food if they’re almost out. I give them a container or two at a time.
  • Put food in different spots on top of the existing bedding and then cover it with a small amount of bedding.
  • Try not to disturb them too much. 
  • Make sure the bin’s not too wet inside; add more bedding if needed. If there’s a drain, make sure it’s not clogged. 
  • When the bin starts to get full, I feed them only on one side for a couple of weeks. Then I can harvest my black gold without too many casualties.*
  • To harvest, scoop out the worm castings from one side, level out the contents, and resume feeding them.*

*Unless you have a different set-up in which the red wigglers follow the food upwards.

How to use worm castings

  • Use some with your seed-starting mix to aid in germination and give your seedlings a strong start.
  • Add some to the soil when transplanting flowers, herbs, fruits, and veggies.
  • Use as a side-dressing around existing plants.
  • Put some castings in cheesecloth and steep them in water to make worm tea, a potent liquid fertilizer.
  • Scatter your black gold in areas where plants seem to struggle.
  • Repeat as needed or every month or so during the growing season.

Check out this guide to create a DIY worm bin using 5 gallon buckets. Munchen Haus and other restaurants regularly dispose of used food grade buckets. Snag them in the alleyways to give them a new life!

Washington Based Worm Vendors

Seattle Worms

Montlake Terrace, WA

Products: red wrigglers, vermicompost, worm bags

Marle Worm Growers

Otis Orchards, WA (east of Spokane, near ID border)

Products: red wrigglers, European night crawlers, vermicompost, bulk organic compost, various soil amendments, various style worm bins

Wiser Worm Farm

Olympia, WA

Products: red wrigglers, vermicompost, worm tea

You can find Sustainable Wenatchee at

Betsy can be reached at