Preparing bedding for worm composting (or vermicomposting)

Bedding is the non-food portion of what goes into your worm compost bin. A number of different materials can be used for bedding, including shredded newspaper, peat moss, animal manure (not dog or cat), leaf mold, ... I use shredded newspaper since I can get it from the neighbors' recycling bins. Avoid any paper with colored (nonblack) ink as it may contain materials toxic to the worms.

Hand shredding it is easy and can be done while watching TV, or anything that'll keep you from getting too bored while doing it. The objective is to tear it into 1/2" to 3" wide strips. Simply hold a sheet up in front of you, oriented as if you were going to read it (but don't read it! Otherwise you'll be sitting there forever.) Grip the top corner with one hand and pull down. You can actually get quite fast at it, doing nice 1" wide strips quickly one after the other.

The results of a shredding session.

The rule of thumb for the amount of newspaper is 3lbs for every cubic foot of volume. My wooden bin has a surface area of 3 square feet and should have about 8" deep of bedding. As a fraction, that's 8/12 of a foot deep. So 3 square feet times 8/12 foot gives 2 cubic feet of volume. Since it's 3lbs for every cubic foot of volume, I needed 6lbs of newspaper.

Next, the bedding has to be moist. Worms breath through their skin and moist bedding helps them do that. The rule of thumb for the amount of water to use is 3 parts water, 1 part newspaper by weight. That's 75% moisture content in the bedding. So for 6lbs of newpaper, I should have 18lbs of water. However, another rule of thumb is that if you're using a bin that retains moisture then divide the amount of water by 3. That would be the case for a plastic bin, and I also figured it applies to my painted wooden bin. So for this case it works out to equal parts newspaper and water by weight. I used 6lbs of water.

I weighed my newspaper on my digital scale before shredding it. Another trick is to first weigh yourself standing on a digital scale, and then to pick up the newspaper and check the weight again. The difference is the weight of the newspaper.

To get the newspaper properly moist, put it in a large garbage bag. Pour the water onto the newpaper in the bag.

But before mixing it, you'll need to add a few tablespoons of sand. The sand is used by the worms in their gizzards to help them break down the food. Worms don't have teeth. I use "play sand" which I found at Home Depot (about $5 CDN for a 20 kg bag, very cheap.) Play sand is for kid's sandboxes so I figured it must be safe for my worms too.

Now mix it all around, both by hold it closed and shaking it, but more importantly by reaching in and moving it around. Grab hold of any dry newspaper and mix it with wet newspaper. The sand particles are small and will tend to find their way to the bottom corners and clump together so reach in and pull it out. Keep doing this in the bag until there are no more dry pieces. Break apart any clumps while you're at it. You want it moist, sandy and loose.

Finally, it's time to put it in the worm composting bin. You want it to be loose, not clumped and heavy. For my needs, I put it in until it was about 8" high. Besides being a place for worms to live in, bedding also keeps the odors from getting out. When opening your compost bin you should see just wet newspaper. If you see anything else then chances are you also smell something.

Ta da!

General maintenance

Bedding is not done only once. Worms consume the bedding and you'll need to add more. The time I add bedding is when I'm having trouble finding clean bedding to hide waste under. I no longer measure the amount of water I added when making bedding. I simply put the dry shredded newspaper in the large plastic garbage bag and pour in some water. I mix it around and if I can't get it all wet then I add more water and repeat. One out of every three or four times I prepare new bedding I also add a tablespoon or so of sand.

The newspaper in the worm comosting bin can dry out. If it does, I simply sprinkle water over it using a watering can.
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