Vermicomposting 101

How to Start a Worm Compost Bin

Fun fact: Food scraps, junk mail and paper products make-up about 30 percent of garbage. Okay, actual fun fact: There’s an easy, and what some may even describe as fun, solution.

Worm composting, also known as vermicomposting, is a simple way to reduce household garbage, and it’s possible to do whether you live in a tiny apartment or a large house! By layering your food scraps with dry materials like scrap paper and cardboard and adding the magic ingredient – worms – you can convert it into compost gold, while reducing your reliance on the landfills that are quickly filling up.

How to Compost with Worms

All worms are not created equal. For vermicomposting, you need red wiggler or red earthworms (probably familiar to you if you fish). Your worms have one mission in life: to eat your food scraps and cast (i.e., poop) it into super rich soil. Not a bad life’s purpose. There are other organisms in there too that help break down your garbage. But the worms, and their health, are the number one priority. (See the links below for where to order worms.)

Vermicomposting Worm Bin Setup

Most DIY worm bins are made from large plastic storage bins with lids. (The size should equal about one cubic foot per person in the household.) Long and wide is better than a tall and narrow bin. Use a drill, or a hammer and nail to poke plenty of air holes in the lid top. Some organizations sell ready-made worm bins with large holes drilled in the sides and screens inserted for ample air circulation (but no worm escapees).

Add moistened, shredded paper (uncoated newspaper is ideal), chopped food scraps and worms (about a one pound of worms should be a good amount for most bins) to the bin, and cover it with the bin lid. About once a week, or every other week, move the material in the bin around to help with aeration. Always keep a layer of shredded paper or sawdust over the top of the pile to discourage smells and bugs. Once you stop adding new material the compost should be ready to harvest in one to two months (depending on how much is added in the last feeding).


Indoor temperature at which worms do best for vermicomposting

Maintaining Your Vermicomposting Worm Bin

The bin should be as moist as a damp sponge. An indoor temperature of 55 to 75 degrees is perfect for the worms. Keep them away from ovens, heaters or air conditioners – too cold and your worms will freeze, too hot and they’ll roast. Remember, the worms create their own heat through their work.

Worms are a little like children – they are picky eaters and they like it when their caretakers chop their food. Cut food scraps into one to two inch pieces, and shred paper before adding it to the bin. This allows more surface area for the worms to eat faster.

If you need to go on vacation, don’t worry. Your worms can be left alone for about three to four weeks without any help. Before you leave, provide them with a freezer bag or two full of food scraps and distribute it evenly around the bin. If you’ll be gone longer, ask a friendly neighbor to feed the little guys once or twice and move things around. After such a long time without care there might be a slight smell to the bin. Follow the tips below to solve this.

How to Harvest the Worm Compost

The compost is ready when it is a deep blackish brown color, and is moist. There may be some small pieces of egg shells or paper remaining. Before you feed it to your plants, you want to separate out as many worms as possible so they can keep working for you. Because worms like it dark and warm, they are often hiding in the middle or the bottom of the container.

Still have questions? Check out these specific harvesting tips and methods.

What Can I Compost in a Worm Bin? What Shouldn’t I Compost in a Worm Bin?

Items you can compost with your worms:

  • Food scraps (including things like melon rinds, roots, stems, leaves, cores, husks, seeds, skins, peels, etc.). Exceptions to this are listed below.
  • Egg shells (but not whole eggs), seaweed and rinsed seashells (like oyster shells; not shrimp peels)
  • Old natural fiber clothing (old t-shirts, socks, boxers, etc)
  • Natural yarn, twine and string
  • Non-glossy paper products (cardboard boxes, newspapers, magazine inserts, most junk mail, envelopes, etc)
  • Tea leaves and bags (remove the staple!); coffee grinds and filters
  • Dead plants, grass clippings, pine needles and leaves – just make sure they have not been sprayed with pesticides
  • Natural non-treated wood and byproducts like wood ash, sawdust and shavings (no coal ash)
  • Feathers and hair (human, cat, dog, etc.)
  • Dryer lint

Items you cannot compost in a worm bin:

  • Lemon, lime, orange or other citrus peels and juice (in excess this will make the soil too acidic)
  • Onions and garlic (a good rule of thumb is if it makes you smell, it makes your worm bin smell)
  • Meat, fats, grease, bones or oils (no butter, lard, stocks, soups, etc)
  • Plastics and plastic coated paper (like glossy magazines)
  • Stickers, including veggie stickers (remove stamps from envelopes)
  • Bread or yeast products (no crackers or cakes)
  • Salt, pepper and other spices
  • Milk, dairy or dairy products
  • Cat or dog feces
  • Diseased or infested plants
  • Treated wood products

What if it Starts to Smell? Troubleshooting Vermicompost Bins

The only smell your compost should have is a slight sweet pleasant earthiness of soil, and should only be noticeable when the bin is open for feeding time. If you notice an off or rotten smell while feeding the worms, or if you notice a lot worms attempting to crawl out of the bin, something is wrong.

  1. The bin may be too moist. Move the soil from the corners. Is there liquid buildup or is the compost extremely runny and muddy? Add shredded paper, especially in the corners, to absorb water and regain balance.
  2. The bin may be too dry. You can puree some veggies to add moisture, or spritz the top with some water.
  3. Infestation. Other organisms live with your worms. Most of the time they will not be noticeable. If you get an infestation, follow the links below for troubleshooting tips and tricks. Most infestations, like fruit flies, are easily avoidable if you freeze scraps for 24 hours before you add them to the bin.

Other Vermicomposting Tips

  1. Try to keep a ratio of 70 percent brown matter (paper, wood, dried and dead plants) to 30 percent green matter (food scraps, young plants and wet leaves).
  2. To reduce the chances of fruit flies (eggs are often laid in items like banana peels) freeze scraps for 24 hours before adding them to your bin.
  3. Give the worms air! Every other week or so, move the compost around to aerate it.
  4. Don’t overwhelm your worms. If you notice smells beginning to form you might be feeding them too much! Reduce the amount you feed them and add a little paper to absorb smells until they can catch up.

Where to Order Worms

You can buy worms on the internet and have them shipped to your door! Check out Gardens Alive and Planet Natural.