Vermicomposting is the process of using worms to compost and transform waste products like kitchen scraps and newspaper into rich compost. Worm castings, the product of worm digestion, are rich in available nutrients for your plants, and increase all the healthy contributors to a balanced microbe system in your garden.
If you are a serious organic gardener, you should be using worms. The best thing about all of this, is that you can be creating amazing soil ammendment/organic fertilizer with cheap start up costs, and using what we would all normall throw away.
There are numerous ways to create vermicomposting bins. I like the method described in the video below, so I won’t be redundant. But I will highlight some points, particularly for arid climates.
- Red worms (Eisenia foetida), are the worms primarily used for vermicomposting. Remember that these are not soil worms. They live in natural compost piles (piles of organic debris that naturally collect). They like oxygen and they don’t like extreme temperatures. Extreme temperatures will cause them to go dormant or die (I will address how to deal with our summers below). I get my worms from Acme Worm Farm in Tucson.
- The environment for the worms needs to be moist, dark and to contain the worms. Bins need to be in the shade, and also protected from the cold in winter. Temperatures are best between 50-80 degrees F.
- If you start your bin in spring or summer, consider having the bin indoors. Mine is under the sink. Inside you can manage the temperature well. Worm bins do not smell if managed correctly and indoors under the sink is ideal year round (and convenient for putting scraps into). Keep chemicals out of this same cabinet.
- If you have your bin inside, be sure to have some sort of tray or other system to collect the moisture that results (notice in the video there are holes drilled in the bottom of the bin. You do not want moisture building up in the bottom of the container. It will drown the worms and cause anaerobic, and therefore smelly, conditions. The “juice” that collects is incredibly rich and good to put on plants as a fertilizer and microbe inoculant.
- Feed your worms a balanced diet of kitchen scraps, mostly vegetables (although some sources say not to use meat and dairy, some is actually ok, but too much can get smelly), cardboard, and shredded paper (avoid the glossy kind), weeds, etc. Make sure not one thing is too dominant. The more diverse the diet of the worms, the better the results. When you first start your bin, add in some finished compost and some soil (not too much). You won’t need to do this too much later, but this will help get the microbe community going, and will give the worms some healthy grit to help them digest. Never put cooking oils or food that is too oily into bins, this will cause worms to suffocate.
- Worms are much better-off when they can breathe well, but stay moist. This is a balance you will have to play with. Just try to imagine the debris piles they naturally live in.
- Remember that worms and microbes do NOT like inorganic fertilizers or pesticides. If any of the food you give the worms has been exposed to these things, it’s going to have a negative effect on your goal. If your vegetables were not grown organically, wash them well (you should anyway if you are eating them). Newspaper is printed with soy ink these days which is fine. But if you have been using toxic paints or markers on your paper, avoid using it for worms.
- Worms don’t eat kitchen scraps right away. They wait for them to start to decompose. When you get your bin started, make sure there is some compost already in the bin to start with, or food that is partially rotted.
- Worms hate light. In the video below the guy is spreading out the worms in full sun. Don’t do this. It’s torture for them. Pick a dark, shady spot for this project and try to do it in the morning. Whenever you transfer worms to a new location, do it quickly. When you show them off to friends, be nice and make it a quick introduction. Honestly, think of them as Mogwai from the movie Gremlins. Protect them from the full sun.
- Some COMPOSTED manure is actually a great inoculant for microbes. Don’t use fresh manure, it will hurt the worms and be smelly.
- If you use compost from the nursery, try to be SURE they have not added fertilizers. Many do. Avoid companies like Miracle Grow and other such companies that love to add stuff like sulfur and nitrogen to their products. I avoid these products ANYWAY because they are not good for organic gardens. Always try to use compost that either you or a friend made so you know what was put into the mixture.
Some notes on doing vermicomposting outside: It is best to start in fall. You can create a condition that will keep worms in one area (and not creep away from where you want them) by using barriers and also just making the situation happy for them. Pick the most protected and shaded part of the yard for your outdoor worm bin. When summer comes, if you manage the bin well, keep it moist (without drowning worms), then they will stick around, possibly go dormant. You may see more worm “cocoons” than actual worms. This is ok. In fall they will get active again and resume their good work.
I like to create a spot IN THE GARDEN that is shaded and layered with waste for the worms to eat–just like in the conditions you create in the bin. However, cover the top with something flat like a piece of old plywood to keep sun out and moisture in. If placed in the middle of the garden, you can skip the step of sifting out worms, and let the results leach directly into your garden. You can move this spot to different parts of the garden each season. Just like in the bin, in summer the population will decrease, and go dormant. But they will revive in fall if the spot is left undisturbed (save for the occasional addition of foods for the worms still active). Some gardeners have been able to keep them active year round by keeping the conditions happy for the worms. This is a challenge if the spot is not in full shade.
Here is a complete guide (a downloadable PDF) on vermicomposting for more information.
Video Guide on Vermicomposting