lancaster.unl.edu/pest/resources/ Vermicomposting: Composting with Worms by Soni Cochran, Extension Associate
Vermicomposting uses earthworms to turn organic wastes into very high quality compost. This is probably the best way of composting kitchen wastes. Adding small amounts of wet kitchen scraps to a large compost pile in the garden day by day can disrupt the decomposition process so that the compost is never really done. But it works just fine with vermicomposting.
Many gardeners use vermicomposting systems for all their garden and kitchen wastes, many more use both types of composting, and thousands of households without gardens use neat and unobtrusive worm boxes indoors to compost their kitchen scraps (as well as newspapers and cardboard boxes), reducing their garbage by up to a third and providing their own organic soil for pot plants and container gardens on balconies and roofs to grow their own healthy food.
One or two people usually produce about 4 lb of food waste a week: use a 2ft x 2ft box 8” deep. For three people make it 12” deep, for more, 2ft x 3ft x 12” deep – or two 2-person boxes might be better, because bigger boxes can be too heavy to move when they’re full.
Use exterior-grade 1/2” plywood. Don’t use chemically-treated wood. Treat the wood with a non-toxic wood preservative, or paint it with vegetable oil, or linseed oil. Use galvanized nails. Drill at least a dozen 1/2” holes in the bottom for aeration, and arrange it so that two opposite sides are half-an-inch deeper so that the bottom stands off the ground. Stand the box in a tray, because it will probably leak a bit.
Once filled, cover the surface with black plastic sheeting (a garbage bag) slightly smaller than the surface area: this will keep the moisture in, and the worms will work right up to the surface. If this makes it too wet, use a couple of newspapers instead. Make a lid for the box. Keep it anywhere convenient.
Fill the box with moist bedding for the worms to burrow in and to bury the food scraps in. You need about 6 lb (dry weight) for a 2ft x 2ft x 8” box. Worms will eat the bedding as well as the food scraps, so you’ll need to top it up in a few months.
Any inert, non-toxic, fluffy material that holds moisture and allows air to circulate will do. Don’t use anything that will decompose too rapidly when you moisten it and get hot, like manure that’s not aged enough or hay, especially alfalfa hay. Mixed bedding is better, but no need to be too complicated: 2/3 corrugated cardboard and 1/3 sphagnum peat moss or coco peat moss is a good mixture, or sphagnum peat moss, shredded leaves and sawdust; or just cardboard and/or newspaper.
- Cardboard cartons (corrugated): cut them up into strips an inch wide and a few inches long. Don't use the shredded cardboard sold for insulation because it's treated with toxic chemicals.
- Newspaper: tear it into 1" strips -- it's easy to tear with the grain. Black ink is non-toxic, avoid glossy paper.
- Shredded computer paper.
- Autumn leaves: spread them thickly in the driveway and drive over them with the car a few times to break them up, or shred them with a lawnmower. Or moisten them, sprinkle some lime, ground limestone or wood ash over them and bundle them up in a garbage bag, tie the top closed, and in a few months they'll have broken down enough to be excellent worm bedding. Or just use them as is, though it'll take a bit longer for the worms to break them down.
- Aged manure, or composted manure: cow, horse, rabbit.
- Sphagnum peat moss: use Canadian peat moss, soak it in water for 24 hours, squeeze it out and sprinkle some lime on it.
- Coco peat moss or coir (coconut fibre): comes in compressed bricks, soak in water and they swell up -- no need to add lime.
- Chopped-up straw or other dead plant material, spoiled hay, yard clippings, dried grass clippings: any plant material "aged" beyond the green stage.
- Sawdust, wood shavings: from non-aromatic wood, avoid treated wood, about a quarter to a third of the bedding mixture.
Add a couple of handsful of soil or sand -- it helps the worms grind up
the food in their gizzards. Sprinkle a bit of lime, ground limestone or
wood ash over the bedding (not too much!). Ground limestone is best.
Worm bedding and feed can be wetter than compost material: 75%, compared
with 65% maximum for compost. Dry bedding usually needs a bit less
than three times its weight in water (a pint of water weighs a pound,
a litre weighs a kilogram).
Once it's all suitably shredded, mixed and moist, put it in the box and
add the worms (about 1lb -- 1,000 worms). Leave it for two or three days
to let the worms settle in before adding wastes.