A worm bin is a quick and easy way to compost your own food scraps. Here’s how to make your own organic fertilizer for the garden by composting with worms.
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We all know that we should fertilize our gardens regularly, but many of us are unsure of how to do it properly and safely without the use of chemical fertilizers. In this article, find out how to make your own natural fertilizer, with very little effort, by composting food scraps in a worm bin.
Worm Castings—The Fertilizer You Need
Worm castings are basically worm poop. Did you know worm castings are one of the richest natural fertilizers that we know of? They contain an impressive list of minerals and nutrients in quantities that outperform other organic materials and manures. The phosphate, nitrogen, and potash levels are through the roof, and are all essential to plant growth.
While livestock manures add volume to soil, they can burn plants if added in excess or before the composting process is complete. Manures are more of a slow-release fertilizer rather than being immediately bioavailable to plants like worm castings.
In addition, manure has a high probably of being contaminated with herbicide, which can destroy soil life and result in crop failures. Backyard compost bins are also becoming contaminated with herbicide in some instances, even when the gardener doesn’t use herbicides in their garden.
What’s more, many gardeners purchase bagged or bulk compost, without knowing that even organic-approved compost soils may be contaminated with herbicide.
While hay, manure, straw, and grass clippings tend to be frequently contaminated by herbicides, food scraps are not, which is one reason why I enjoy keeping a worm bin.
There is no maximum limit to the quantity of worm castings you can apply to the garden, meaning you can’t accidentally apply too much. Luckily, even a tablespoon of castings per plant would be enough to improve plant health and vigor, and increase the amount of beneficial soil organisms that are present.
Worm castings help plants grow vigorously and protect them from disease by forming beneficial relationships with the roots of plants. They also help retain moisture in the soil.
Worm castings can be easily purchased in bags, but it’s just as easy to make your own with a worm bin!
Make your own worm bin for vermicomposting!
Vermicomposting is a fancy word for worm composting.
It’s a great way for city dwellers to dispose of kitchen scraps because of the small footprint of a worm bin.
However, I think worm composting is a boon for all gardeners, because worm bins are so easy to make and yield such an important soil amendment.
I keep my worm bin in our garage, and when the compost pile outside is frozen in winter, I can continue to compost food scraps. There are many store-bought varieties of worm bins, but DIY worm bins are so easy and inexpensive to make.
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Worm Bin 1.0
One Christmas years ago, my brother gave me my first worm bin made from a plastic tote. He simply drilled two holes in each side for ventilation. I had been wanting a worm bin, but I was afraid I would do it wrong and attract bad smells or fruit flies. Now I had no choice: The worms were in the mail, on their way!
I did, in fact, experience some problems with that first bin, such as fruit flies. However, I learned that I had simply been doing it wrong. A few quick fixes, and I was up and running.
Harvesting Worm Castings from a Worm Bin
After keeping worms for a year, I had gotten the hang of managing them properly. However, I was still having problems with harvesting the castings.
It turns out, harvesting from a single worm bin didn’t work for me.
I tried feeding them only on one side, hoping that when that side filled up I could begin feeding them on the other side. In this plan, eventually the worms are supposed to migrate to the new side where the food is, so I can harvest the castings on the first side.
There were always lots of worms in all areas of the bin, and I didn’t want to add the castings—with worms—into the garden.
An alternative strategy for harvesting the castings is to spread out a sheet of plastic on the ground and scoop out handfuls of worm castings, placing each in a cone-shaped pile on the plastic (like a party hat!). After a few hours, the worms migrate to the bottom of their cone, allowing you to harvest the top 2/3 of each pile.
This totally works, but it’s a lot of work.
So I decided to build a new bin with easy harvesting in mind. After some research, I decided on the following design.
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Worm Bin 2.0
Here are my step-by-step instructions for the worm bin that has lasted years and has produced many loads of great worm compost.
- 2 (10-gallon) plastic totes + lids (dark colored, no clear plastic)
- Drill + 1/4″ and 1/8″ drill bits
- Shredded office paper and newspaper – enough to fill a bin
- spray bottle with water
- Red Wiggler Worms (1,000)
- 1 cup of food scraps (fruits, veggies, egg shells, coffee grounds. NO garlic, onions, or hot peppers). I collect them in my countertop compost pail with carbon filter.
- 4 bricks
How the Bin Works
The worms and the composting happen in one bin (tote). When it gets full, the lid is removed, and the second (empty) bin is placed right on top of the compost surface of the bottom (full) bin.
Bedding and food are added to the new bin on top. Over the next 2-3 months, the worms migrate up through the holes to the new bin, at which point, the bottom bin is 98% worm castings. You’ll still want to sift through the finished compost to find wayward worms and return them to the new working bin.
Although this process takes longer, it’s a lot less work to harvest the castings than from the single bin.
Constructing and keeping a worm bin is fun for the whole family! This bin is featured in Teri Page’s book Family Homesteading. Check it out for more tips on gardening with children!
How to Build this Worm Bin in 9 Steps
Drill about 50 holes in the bottom of each bin using a 1/4-inch drill bit. This is for drainage and through which the worms will migrate upward to the empty bin.
Create ventilation holes by drilling about 60 holes just under the top edge with a 1/8-inch drill bit, as well as about 50 holes in ONE of the lids.
Add half of the shredded paper, moistening it with the spray bottle. It should feel like a wrung out sponge. This is the bedding.
Add the worms. In my case, I dumped in the contents of the old bin, so the worms went in with some castings and food scraps. You can add a few handfuls of loose garden soil or leaves if desired, but it isn’t necessary.
Now add food scraps and spread it all out evenly.
Top with the other half of the shredded paper and moisten well.
Locate your bin’s ideal permanent place. The worms don’t like temperature extremes, such as really hot summers and really cold winters. 55-75 degrees Fahrenheit is ideal. I keep my bins in the attached garage.
Place the lid without the holes on the ground and place a brick in each corner, and set the bin on top of the bricks.
To feed the worms, pull away the shredded paper on top, pour in the cup of food, then replace the shredded paper so all food is covered.
Worm Bin Care
Only feed the worms about one cup of food each week for the first few months. As the worms look bigger and more numerous, you can increase the amount of food scraps you give them each week.
Over time, the bedding (shredded paper) will break down. Just add more shredded paper if that happens, moistening it with the spray bottle.
Monitor the moisture level. The contents should always feel like a wrung-out sponge. If lots of liquid seems to be draining out the bottom onto the bottom lid, this could mean that you’ve added too much water. Just let the moisture levels balance out on their own, perhaps lifting the lid once a day.
Learn better by video? Watch me make my worm bin.
Worm castings are an easy, inexpensive, and important fertilizer for the garden. Will you build a worm bin this year?
- 7 Ways to Improve Soil Quality
- How to Keep Herbicides out of your Compost Bin
- How to Source Herbicide-Free Compost Soil
>>> Get my free 19-page Guide to Organic Soil Amendments for more ideas: