“It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.”
Charles Darwin made this observation about earthworms in his 1883 book, The Formation of Vegetable Mould Through the Action of Worms With Observations of Their Habits.
Darwin published this book shortly before his death, it was the result of 40 years of studying the habits of worms. And you thought natural selection was his thing.
Darwin was fascinated with worms for a good reason. They are our best soil managers. Their movement aerates the land. The tunnels they dig allow water to penetrate deeply into the soil. Plant roots utilize these nutrient-filled tunnels for their own growth. Worms break down organic matter like fallen leaves and dead bodies, moving them through the soil strata. In their wake, they leave behind castings, some of the most valuable plant food.
What is a Worm Bin? (Clue: it’s a Bin Full of Worms)
A worm bin uses the power of worms to transform kitchen scraps into valuable plant nutrients. This process is also called vermicomposting.
It is important to note that a worm bin is not the same as a compost bin. While they share some similarities, a worm bin uses worms exclusively to break down organic matter whereas a compost primarily works through bacteria. A worm bin is not a substitute for compost, it cannot process the amount of organic material a typical household creates. It is instead a compliment to a compost bin.
For apartment dwellers, a worm bin works great on a balcony or under a kitchen sink (if the bin is very well maintained). I once kept one in an apartment parking spot until it was stolen, I hope the thieves cared for my worms as much as I did.
How To Build A Worm Bin
First, gather your materials:
- Power Drill
- Bedding Material/soil
Start with an opaque (worms don’t like light) bin with a lid. Most bins will work. Keep in mind that a large bin will hold more worms but will be heavy to move. Ten-gallon containers work great. Grab the bin from your garage that is full of pictures your kids drew for you, throw out the pictures and use that bin. If you don’t have a bin you can order one cheaply on Amazon.
Give Your Worms a Breath of Fresh Air
Your worms will need air. Using a 3/16 inch drill bit (you want the holes small enough that the worms cannot easily crawl out), drill a row of holes near the top of each of the four sides of the bin. Drill each hole about two inches apart.
Drill another two rows on the lid of the bin.
Flip your bin over and drill about 4 holes (one in each corner) on the bottom of your bin. These will be for drainage. If liquid accumulates in your bin you can drill more holes.
Make the Bed
Like in a compost pile, you must maintain a balance of carbon and nitrogen material in a worm bin. This carbon material is also called bedding (because it also acts as a medium for the worms to move through).
Bedding can be fallen leaves, coconut coir, straw/hay, aged cow or horse manure or shredded newspaper. I prefer to use shredded newspaper (the more shredded the better) because I have a ready supply of it (not because my worms like to keep up with what Trump is doing). Some people have concerns about the toxicity of newspaper ink but most newspapers now use soy-based inks. In the past, it was common for newspaper ink to contain heavy metals (check with your local paper to be sure).
Throw in a cup of your native soil. Worms don’t have teeth but instead grind food in their gizzard. Soil provides needed grit for digestion.
Add water to your bedding until it is the consistency of a wrung-out sponge.
Prepare your bin with the drilled holes and bedding before getting your worms (as soon as you receive them you will want the bin to be ready to go).
Find Some Worms
Red wigglers (Eisenia foetida) are the worm to use for worm bins. Do not dig up earthworms for your bin, they will be miserable. Red wigglers, on the other hand, happily live in crowded conditions and thrive off of decaying organic matter.
Take a large scoop of worms from a friend’s bin for your own bin (a healthy worm bin will double its population every three months). If your friends aren’t the worm types, you can find red wigglers the same way you found your couch and roommate, Craigslist.
If Craigslist does not turn up any results buy your red wigglers from Uncle Jim’s Worm Farm. I have bought worms from other suppliers, they showed up thin and barely moving with a note inside explaining that this is normal and as soon as they enter a moist bin they will rehydrate and become active, they didn’t.
Uncle Jim’s Worm Farm red wigglers, on the other hand, show up plump and active. They seem excited to get in your worm bin and they stay that way.
Uncle Jim’s Worm Farm red wigglers show up to your house excited to move into their new home.
Show Your Worms Around Their New Home
Place your worms into their new home and cover them with one inch of bedding. Your worms need to adjust to their new home and will not eat so much at first. Add one cup of food (see below) under one inch of bedding. Check back in two days to see if they are eating it, if so add another cup.
At first, you will have to keep a close eye on the worms to gauge how much food to add. Too much food will turn rancid and attract unwanted guests. After a couple of months, your worms will have settled in and will eat much more quickly.
Feed Your Worms Like Queens and Kings
Worms are voracious eaters but keep in mind they have tiny mouths. The smaller the pieces that go into the worm bin the better. Some people even blend their kitchen scraps before adding them.
- Coffee grounds and tea leaves
- Old rice/oatmeal/bread and other cooked grains
- Vegetable scraps (except garlic and onions)
- Fruit scraps (except citrus)
- Rabbit poop
- Crushed eggshells
Worms Don’t Enjoy
- Processed foods
- Garlic or onions
After you add food, cover it with one inch of dry bedding, this will help keep fruit flies away.
A compost crock on your kitchen counter is a good place to store kitchen scraps before taking them to your worm bin.
Keep That Bin Healthy
Keep your bin out of direct sunlight. Worms like moderate temperatures (Between 50 to 70 degrees Fahrenheit). You can keep your bin outside if you live in a moderate climate. But, make sure the lid is secured from racoons, dogs and other hungry animals.
If your climate is too cold or hot move the bin into an area like a garage where it will remain at the appropriate temperature. If you do store your bin inside for all or part of the year you have two options concerning the bottom drainage holes. Either do not drill any drainage holes and monitor your bin regularly to make sure liquid does not accumulate. Or, place your bin inside of another bin with some risers on the bottom. The liquid will drain out and collect in the bottom bin.
Your bin should remain the consistency of a wrung-out sponge and should stay airy. If the contents of the bin are too wet or dense, mix in more dry bedding.
Your bin should not become deeper than eight inches. If it does and your worms are doing well, start a second bin or share some worms with a friend.
If you go on vacation no need to bring your worms along, just add extra fresh bedding and food.
Harvest the Castings: Black Gold
When the contents of your bin are mostly black it is time to harvest. The trick is to harvest the castings without the worms inside of them. Worms don’t like light so try opening your bin and letting the sunlight in. Your worms will burrow down and you can scrape some castings from the top of the bin.
A slower method but one that will produce a larger harvest is to move all of the contents of the bin to one side. Begin adding food to the empty side only. In time, the worms will migrate to the fresh food leaving behind a nice pile of castings.
You can sprinkle the worm castings around the base of plants. I like to place a spoonful of castings inside of the holes when I transplant.
Worms: Man’s Best Friend
As you maintain your worm bin you will find yourself growing attached to the little wigglers. You will learn their food preferences (mine are Californian and love avocados), notice little babies in the bin and if you get really into vermicomposting, may even give your worms names.
Worm bins are a great project for children as well, they love digging through the bin and looking at the worms through magnifying glasses.
Let us know how your worm bin is doing in the comments below.