Worm castings are one of the best unknown secrets in the gardening world. Castings contain millions of natural microbiology that is just waiting to do work for you cycling nutrients, fighting pathogens, and amending your soils.

This method of worm composting is for use with Red Wiggler worms also known as Red Worms. If you want to be scientific they are Eisenia fetida species of worm. They are a special type of composting worm that is not a true earthworm. It is a manure worm! They live in the top 2 to 6 inches of soil. You can find them sometimes sold as fishing worms.

Do not use Night Crawler Worms or Lumbricus terrestris species of worms. These are important for the soil food web, but they are not food composting worms. They tunnel up to 3 feet deep and they do not do well in a shallow worm box environment. You may however try this method of growing worms if you want some fishing worms.

Building your own worm composting bin is easy and fun. You can make lots of beneficial worm castings (worm compost) to make compost tea out of, amend potting soil with, plant seeds with, or use as a topdressing on plants in the ground and in containers.  You only need to know a few things about worms to begin:

Worms need moisture -Red Wigglers need a constant 70% moisture level

Worms need warmth -They prefer their bedding temperature to be between 55 to 75 degrees.

Worms need a food source – The more diverse the food you give them, the higher quality your castings will be. In addition to your kitchen scraps, consider giving them things such as humate (liquid humus), molasses, fish emulsion, and seaweed. The more varied the food the better. If using manure, it should be held to 20% of the bedding and should be aged first.

Worms Hate: Worms Love:
Meat Vegetable Scraps
Fish Fruit Rinds, Peels, and Scraps
Cheese Breads and Grains
Oily Foods Coffee Grounds…filters too
Butter and Fats Tea Bags
Pet Wastes Partially Composted Leaf Litter
Their Own Poo Aged Dairy, Horse, Rabbit, or Poultry Manure

Don’t over feed your worms. There is a 2:1 worm to food ratio. You need 2 lbs of earthworms for each pound of food consumed a day. There are 600-1000 worms per pound. In other words, put your excess food scraps in the compost pile. Don’t over feed your worms! To start a simple 20 gallon tub you will need about 1000 worms.

Worms need darkness – Make sure your worms are in the dark. Use a dark, non see-through container. Worms are sensitive to light, and it can even harm them.

Worms need oxygen – Air circulation is a must. Worms need oxygen to survive just like we do.

Worms need dirt – A handful of soil mixed in with your bedding materials is essential so that the worms can use the ‘grit’ to grind down food particles in their gizzards. Worms don’t have teeth. The food waste must be decomposed by the micro flora first before an earthworm can consume the waste. That is why it is beneficial to add food wastes in smaller pieces rather than ‘chunky’ ones.

Worms need love (Don’t we all?) – If you have happy worms then they will multiply like crazy. Worms are hermaphroditic meaning they contain both sexual parts, but mating is still necessary. They mate at any time of the year. They are attracted to each other (maybe because of their beautiful bodies and faces or other irresistible qualities) and lie with one another in opposite directions and exchange sperm. They then produce a cocoon that will hatch out 3 or 4 worms.

When worms have to compete for food their population goes down. If you have a ton of worms, you may consider starting another composting bin or giving some to a friend so they can start their own box.

They also do not like swimming in their own castings. It is actually toxic to them. So harvest you castings regularly every 30-60 days.

Harvesting Castings – You may screen your castings if you wish. You may use a 1/8” screen for super fine castings, but I prefer to use a 1/4” screen. Simply keep the castings in a container that is not closed off from oxygen to keep the microbes in the castings oxygenated and happy.  Keep them slightly moist and they will keep for a very long time. Always remember fresh castings are best!

If making compost tea, I prefer to remove the top 6 inches or so and use the unscreened worm compost to make my tea. It tends to have more beneficial fungal strands in it, especially if it has not been disturbed too much and has had a diverse food source.To start your bin over again, add fresh bedding along with the materials that did not go through the screen back to the bin.

Worms are dying or trying to escape Too wet Add more bedding
Too dry Moisten bedding
Bedding is used up Harvest your bin
Bin Stinks Not enough air circulation Add ventilation holes
Too much food Do not feed for 1-2 weeks
Too Wet Add more bedding
Fruit Flys or Bugs Exposed Food Bury food in bedding
Dust with food grade DE



What you will need:

  • An 8-10 gallon Tupperware storage container (not the see through kind)
  • Drill and 1/4”-1/2” drill bit
  • Bedding Material – I like shredded newspaper, peat moss, and coconut coir. Make sure they are moistened
  • Red Wiggler Worms
  • Handful of topsoil or sand for ‘grit’
  • Handful of compost
  • Food for your worms
    • Drill holes in sides and bottom of Tupperware container. Make sure the tub can drain well.
    • Start on the bottom by layering your bedding materials throughout the box. Soak the bedding materials in water first to make sure they are fully hydrated. Squeeze the excess water out before adding it to the box. You want it damp but not soggy.
    • Add your topsoil, compost, and worms to the box.
    • Bury your food waste in the bedding materials.
    • Don’t disturb your worms too often.
    • Feed your worms, but don’t over feed your worms. If in doubt, underfeed them rather than over feed them.
    • Harvest your castings every 30-60 days. This is very important or your worm colony will dwindle. No one likes to sit in their own poo!