Posted by Deana Wise, Broomfield County Extension
Vermicomposting simplified: Worms + A box + A bed+ Food= Living compost. Of course we all know very few things are that simple. What kind of worms should we use? What type and size of box works best? Do they prefer a hard or soft mattress? Are they on a vegan, vegetarian, or gluten free diet? This sounds more complicated than I originally thought.
I became interested in vermicomposting due to an article I read in the Small Acreage Newsletter (www.ext.colostate.edu/sam/nl/15-spring.pdf). This web-site is definitely worth looking at. I digress.
I have had limited experience in composting (sad but true) and even less in raising worms. My grandmother kept a bathtub full of them outside that she used for fishing in the good old days. She fed them coffee grounds and replenished them with “wild” ones she caught in the yard.
After doing a little research, I learned the worms she had were Night crawlers. They are anecic, which means they live in deeper soil and drag OM to permanent burrows. They are the worms responsible for our lumpy lawns.
Brown worms (endogecic) live in temporary burrows in the upper soil. We commonly encounter them every time we turn our garden soil.
The worms that work best for making compost are the epigeic or surface worms. They eat decaying matter and are usually in the top 6-12” of soil. They will not tolerate cold temperatures less than 40 degrees F so they will not survive year round in the garden. Red wigglers (Eisenia foeiteda) are most often used because they reproduce more rapidly than other types (VERMICOMPOSTING: the secret life of compost worms, http://www.ext.colostate.edu/pubs/columngw/gr141101.htm ).
Any type of box will do as long as it is not clear. It must have a lid and drainage and air holes on the top and sides. Holes on the side should be ½ to 1” diameter, holes on the bottom should be ½”. The worms will not crawl out of the bottom; they stay in the top few inches of soil and move upwards. A catch tray underneath will be useful to control leachate. This liquid needs to be discarded, it is NOT compost tea. A box 2’ x 2’x 8” with ½ lb. (500) worms is adequate for 2 people.
Once the box is ventilated, add shredded newspapers or non-pastel colored paper until the container is 2/3rd full. Do not use corrugated cardboard or highly colored inserts or magazines. Spray the paper with water until damp but not wet. Add 1-2 pounds of top soil or peat moss. The worms need the soil because they have a gullet instead of teeth. Do not stir or compact. The worms need to be able to move about freely. Move some of the paper aside, place the worms in the box and re-cover them. It may be necessary to dampen the bedding if it dries out. Keep the box out of direct sun. They prefer temperatures between 40-70 degrees F.
They like to eat fruit and vegetable scraps and peelings, coffee grounds, used filters, tea leaves, tea bags (pull them open), and crushed eggshells. Use onion and citrus very sparingly. Do not use meat or dairy products, manure of any kind, salts, sauces or dressings. The worms will eat the bedding and the food.
Feed about 2-3 Cups per week / pound of worms to start. Increase the volume of food every week (up to ~5 pounds). The worms will reproduce 5-6 times in 3 months so you will have to increase the amount of food in the box. If there is inadequate food, the worms will eat their own castings. These are poisonous to the worms. After 3 months, everything in the box will be composted. Feed in a different spot each time to move the herd. (I never knew a bunch of worms are called a herd).
To harvest the compost after 3 months, feed on one side to move the herd. This may take a few days, they do not move very fast. Remove compost from that side, add new bedding and food. Harvest compost on other side and remove ½ of the worms. Start again. Give remaining worms to friends or start a second box. Fort Collins has a worm recycling program to give your extra worms a good home. Go to http://m.fcgov.com/recycling/worm_exchange.php to check it out.
On a small scale, this process will not produce a lot of compost; however, it may be a preferable method in some ways. Vermicomposting is a cool process compared to the heating involved with traditional composting. Beneficial microbes survive and flourish in worm poop, making it a plant super-food. The compost can be steeped in water to make compost tea. The compost is great for starting seeds and potting houseplants. It can also be used in the garden as a soil amendment.
The main drawback that I see is the disposal of the excess worms every 3 months. The worms cannot be forgotten or ignored. A fair amount of care is needed to keep the worms alive. Perhaps I will give it a try. I have friends that might like worms.