Vermiculture, also known as worm composting or vermicomposting, is the process of using worms to turn scrap organic matter into a nutrient-rich compost. It's a bit like running a tiny worm farm or keeping the worms as pets -- they require a comfy home and food to thrive. Using worms to compost can be a rewarding process as they recycle unwanted materials into something useful to the soil and garden.
Not all worms that look like earthworms are good for vermiculture. The preferred composting worm is the red wiggler, also known as Eisenia fetida, and sometimes referred to as a redworm. This type of worm doesn't burrow as deeply as others, such as nightcrawlers, and typically makes their home among dead leaves and decaying materials, which means they're perfect for compost piles and actually prefer that type of environment. Nightcrawlers, on the other hand, dig burrows up to 36 inches deep, coming to the surface to grab some food to take back down into their homes. They do not thrive in a shallow worm bin environment. Worm populations fluctuate -- if there's not enough food, their population will decrease. They'll reproduce when there's food aplenty. If it seems like the worm population is too high for the bin, transfer the entire environment to a larger bin, pour the contents of the original bin out onto a plastic tarp and scoop some of the worms out to add to a new worm bin environment. Worms don't enjoy being touched, so use a flat piece of cardboard to scoop them and bedding materials over into the new home.
Vermiculture requires bins as a means to keep the worms in one location; otherwise, some are likely to roam away from where you put them. A basic storage bin or tub, such as an 8- or 10-gallon plastic bin with a lid, creates a manageable vermiculture environment. Drilling holes in the bottom allows liquids to drain out, while holes near the top of the sides and also the lid allow for ventilation. Besides the outer structure, the worms need bedding for burrowing. Shredded strips of newspaper or cardboard, soaked in water and then wrung out, create a comfy environment for the worms. A handful of dirt in the mixture aids in digestion once food is added.
Like most living creatures, worms require certain conditions to be happy and healthy. A worm bin or tray should be stored in a somewhat cool environment, generally 55 to 75 degrees Fahrenheit, out of direct sunlight. The worms do not like bright light, but more importantly, direct sunlight can create extremely warm conditions inside the bin, even if the ambient temperature outside of the bin is comfortable. They also need a little bit of moisture -- enough for the bedding material to feel slightly damp, but not soaking enough for water to pool or drip out the bottom of the bin.
What to Feed Worms
Worms eat plant-based kitchen scraps that otherwise might go in the trash or a compost pile, such as fruit and vegetable scraps, coffee grounds and even eggshells. While worms potentially could break down meat- or dairy-based matter, it's not recommended to feed them such things as this may cause the bin to stink, and attract insects and vermin. The materials also may spoil.
How Much Food?
You may be wondering how much worms eat, which is an important concept if you decide to start a worm composting bin or worm farm. Worms that are used to their environment, which may take a week or two after being placed in a worm bin, eat approximately half their weight in food every day. That means if you've placed a pound of worms in the bin, they'll go through a half pound of fruit and veggie scraps each day. Worms don't need to be fed every day, however, so feel free to feed them every two or three days, once a week, or as your schedule allows. The worms will adjust as long as their environment stays suitable for them at all times.
Worm castings is a fancy term for the waste worms create after eating food. The substance is rich in nutrients for the soil and can be mixed into garden soil to improve it, resulting in healthier plants. Compost worms can produce their own weight in castings each day. Castings also can be watered down to produce "compost tea" to apply to soil or around plants in liquid form. In approximately 4 months it's time to harvest the castings -- you'll be able to tell because the environment around the worms looks like a lot of dark soil rather than bedding and food you originally added. Push the castings to one side of the bin and put fresh bedding on the other side. Only add food to the new bedding side. The worms will migrate to the fresh materials. Once the worms have moved away from the castings, scoop out the castings and save them for the garden.