Vermicomposting is the technical name for what has become known as worm composting—the process of using various species of earthworms to digest and convert organic material into useable garden compost. Traditional ready-made vermicomposting bins can be a convenient way to start turning your food scraps into compost for the garden. There are often two problems with ready-made bins: either they're too expensive or they're too large. Worm bins can cost upward of $100 or more in many retail outlets. While they work well, most gardeners would rather spend their money on plants.
The space issue is maybe even more bothersome. Often, the most convenient place to store a worm bin is inside a kitchen cabinet. They're out of sight this way, and it's a convenient place to dump your veggie and fruit scraps. However, kitchen cabinet space is often at a premium and a large, tub-type bin takes up too much valuable space.
The solution to both the financial and space issues is to make your own worm bin. Five-gallon buckets, such as the kind you can buy from your local home center for a few dollars, fit the bill perfectly.
Tools and Materials
Creating your own vermicomposting bin is a very inexpensive project. Here's what you'll need:
- Three plastic buckets: The five-gallon size is best—buckets that are too small will dry out quickly and won't have enough space for your composting needs. You can also use the buckets that kitty litter comes in. The important thing is that the buckets are the same shape and size so that they stack perfectly.
- One bucket lid: Most home centers also sell lids for the buckets they sell. If you're going the kitty litter bucket route, just save one of the lids.
- A drill: A power drill with a 3/16 and 1/8 inch drill bit.
- Shredded newspaper or cardboard: Use this for your worm bedding.
- Red wiggler composting worms: This bin will easily accommodate between 250 and 500 worms.
Vermicomposting bins are structured so that the worms will start out with bedding and food on one level. As that level gets digested and turned into vermicompost, you start adding food and bedding to the next level. The worms instinctively migrate up into that level, leaving behind finished vermicompost for you to use in your garden. You simply keep switching back and forth between the two buckets, emptying finished compost then adding fresh food and bedding as the worms break it down for you. So what's the third bucket for? To catch any moisture created as a byproduct from the other two bins—you can harvest this "vermicompost tea" and use it to fertilize your plants.
- In two of the buckets, drill 3/16-inch holes in the bottom, about 1 inch apart. Do not drill holes in the third bucket.
- Drill a line of 1/8-inch holes through the lip of both buckets, near the top. These holes will provide airflow for your bins, so they don't get too wet.
- Drill a bunch of 1/8 inch holes through the lid, for added aeration.
- Stack one of the bins that has holes in the bottom inside the bucket without holes. Add 3 to 4 inches of moistened shredded newspaper or cardboard to this bucket, then add your worms. You can also add some food scraps at this time.
- Just put the lid on the bin and let the worms do their thing. Add food as often as you need to.
- Once the contents of this layer have been partially digested by the worms, stack the next bucket (with holes in the bottom) onto the bin, adding fresh bedding and food to the new bucket and placing the lid on top. The worms will start migrating up to the top bucket for fresh food and bedding.
- Allow a couple of weeks to ensure that most of the worms have migrated to the top bin, then harvest the vermicompost from the underlying bucket.
- Keep repeating the process as the buckets get full.
Also, be sure to check the bottom bucket regularly for any liquid that has drained from your worm bins. This "tea" can be used on houseplants, container gardens, or just about anywhere in your garden.
Tips for Vermicomposting
This is a very simple system, but there are some things to keep in mind:
- Don't let the contents get too wet. If they do, there are a number of ways to fix a wet worm bin, such as adding more fresh bedding.
- Don't let the contents dry out, either. This is death for worms. The contents of the bin should feel as moist as a wrung-out sponge.
- It is a good idea to add a few handfuls of the original vermicompost to the new bins as you add them. This will introduce a few worms—and maybe eggs—to the new bin, as well as other beneficial microorganisms to help with the decomposition process.
- Maintain several worm bins for maximum composting capacity. Line them up in your basement or mudroom, and you'll always be able to compost your kitchen scraps.