Vermicomposting: Winter project prepares for spring planting

By Jean English | Feb 04, 2012
Photo by: Jean English A simple worm composting bin with a cider vinegar fruit fly trap on top.

Tired of trekking out to the compost bin in winter? Consider vermicomposting.

Vermicomposts, according to the Soil Ecology Laboratory at the Ohio State University, “are organic materials, broken down by interactions between earthworms and microorganisms, in a mesophilic process (up to 25 C, 77 F), to produce fully-stabilized organic soil amendments with low C:N ratios.”

They’re also a convenient way to recycle food waste into a product that supplies plant nutrients, supports a diversity of soil life, helps retain soil moisture, and may increase plant growth and yield significantly – not just because of the above properties, but because vermicomposting produces plant hormones and growth regulators. Vermicompost can also counter some pests. Currently, Cornell University is studying the product’s ability to colonize a seed surface and protect seedling from a Pythium fungus that causes damping off, a common problem in producing seedlings.

A worm composting bin can be made from a rubber, plastic or galvanized tub, or from wood. Figure about one cubic foot of bin space for each pound of food waste produced each week, or about four cubic feet for two people. Ventilate the bin so that the worms can breathe. The simplest design I’ve seen is Wormmainea’s, at wormmainea.com/Worm_Bin_Instructions.pdf. A more complex but functional design is at mofga.org/Default.aspx?tabid=720.

Cover the bin to exclude light (worms like the dark), to retain moisture and deter fruit flies. Keep the contents around 50 to 80 F and out of direct sunlight; e.g., under a sink or in a basement.

The most commonly used worms are red wigglers, Eisenia foetida, because they eat about half their weight per day and reproduce fast. You can get these from Wormmainea (above), F.W. Horch in Brunswick (fwhorch.com), The Worm Wiz in Bowdoinham (thewormwiz.com), or from a friend who has an active vermicompost bin already. City Farmer (cityfarmer.org/wormsupl79) links to U.S. and Canadian suppliers. Figure about one pound of worms per square foot of surface area of bin.

Worms need bedding, half- to one-inch-wide strips of paper (not glossy); straw, shredded leaves, composted cow, horse or rabbit manure, or peat moss. The bedding absorbs and retains moisture, keeps the bin ventilated, and feeds the worms. Place the bedding in water until it’s moist, then squeeze out excess moisture and fill the bin about three-fourths full of fluffed up bedding. If the bedding dries while it’s in the bin, sprinkle a little water on it.

Add a couple of handfuls of soil to provide roughage for worms, which aids their digestion, and to supply microorganisms that also help break down organic matter.

Finally, make a hole in the bedding with your hand and add the worms, pulling some bedding back over them.

Feed the worms at least once each week with small pieces of produce scraps, eggshells, coffee grounds and filters; do not give them meat, bones, dairy products, eggs, fish, or oily foods, since these create odors and can attract rodents. Also, don’t add tobacco products or human or pet waste, and limit citrus scraps, which can lower the pH in the bin too much.

Make a hole in the bedding and place the food scraps in the hole, covering them with at least an inch of moistened bedding to deter fruit flies. Place the scraps in a different area of the bin each time you add them. Fluff up the bedding weekly.

The vermicompost should be ready to use after three to six months. Since worms move away from light, dry areas, remove the bin cover, put the bin in the light, or shine a light on it, and let the worms migrate downward for about half an hour, then scoop the castings from top layer. Wait another half hour and remove another layer, and keep doing this until you’ve nearly reached the bottom of the bin. Variations on this step exist, including dumping the contents onto a tarp and waiting for the worms to migrate to the bottom of the pile.

You can add a little vermicompost to a potting soil mix, add a handful to planting holes in the garden, or topdress plants with it. Some people steep a couple of tablespoons of vermicompost in a quart of water for a day and water plants with the tea.

The main problem encountered with vermicomposting, and a reason a couple of friends have given up on it, is fruit flies. Wormmainea suggests vacuuming the area twice a day for two weeks if fruit flies become problematic; and you can make a trap by putting cider vinegar in the bottom of a jar and covering the jar with plastic wrap, poking holes in the plastic with a paper clip. The flies are attracted to the vinegar and then can’t find their way out of the jar. Replace the vinegar weekly. Other troubleshooting tips are listed at bae.ncsu.edu/topic/vermicomposting/pubs/worms.

Comments (0)
If you wish to comment, please login.