Putting Worms to Work

by Sarah Matthess

Looking through one of our `Backyard Scientist' books recently, we came across an experiment with worms. As a child, I had been interested in the narrow glass tank that stood on the science lab bench at school. The tank contained layers of sand and earth of various colours, with leaves on top. These leaves were slowly dragged down under the surface of the soil by the worms and consumed. The experiment in `Backyard Scientist' is a similar one, although it does not require any specialised equipment. Instead of a tank, they suggest the use of a jam jar.

It occurred to me that perhaps we could expand on this experiment a little. I had seen adverts in gardening magazines for `wormeries' - and very expensive they are, too! After a little investigation I found that one can be created at home with very little trouble or money. It will produce odour-free, nutrient-rich, organic compost, called worm castings. You can get rid of your kitchen waste without tramping through the mud to the compost heap. Children will be intrigued to see how the potato peelings and apple cores disappear.

To start a wormery you first need the right type of worm. Those great fat earthworms won't do the job efficiently; they are too sleepy and don't eat enough. You need the little red worms commonly found in the manure pile, Eisenia foetida, or Lumbricus rubellus as an alternative. Rubellus is the most likely one to be found living in your garden, but it needs plenty of organic matter to survive. It has red and buff coloured stripes, and the adult is between one and a half and three inches long. Believe it or not, it can live for up to fifteen years. It can be purchased at fishing tackle shops, or alternatively, to be sure of getting the right species, it can be obtained through those gardening magazines.

The literature that I have seen on worm composting says that a few pounds of worms are needed, depending on how much kitchen waste you generate. A rough guide is two pounds of worms to every pound of scraps that you add each day. We decided to start with considerably less than this, as worms breed very quickly if given the right environment.

Worms aren't fussy about where they live. However, they do need ventilation and drainage holes. A large plastic storage box with lid, and preferably a tray to set it on, would do the job. A wooden box could be used instead, but it would not last so long. We have made our wormery out of a heavy plastic storage box, with holes drilled in the bottom. The worms cannot survive temperatures below fifty degrees fahrenheit and it shouldn't really be warmer than eighty degrees, so a conservatory, porch or heated greenhouse would be suitable environments. We keep ours in the larder, covered with an old fertiliser sack.

To fill the wormery, first rip up a pile of newspapers into two or three inch strips and then soak them in water. Squeeze them out and lay them loosely in the base of the box. Sprinkle a few cups of potting compost or good garden soil on the paper, so that the worms have some grit for their digestion. Next, add a layer of kitchen scraps. Worms will eat anything, even thick orange rinds, but meat and bones may make the pile stink. Finish the box off with another layer of damp shredded newspaper, and finally add a lid to stop it drying out.

Add new scraps to the box on alternate sides, and try to keep the wormery light and aerated so the worms can move freely. Keep a bag full of shredded newspapers handy so that every fresh addition of kitchen scraps can be topped off with the damp paper, and preferably with a handful of soil. This will keep the small fruit flys away. When three or four inches of castings have accumulated, stop adding scraps to one half of the container; the worms will all move across to the new material, leaving one side more or less clear for harvesting. To close down your wormery, remove the entire contents and sift out the worms with a garden sieve. The worms can be added to the next container you set up or, if you have had enough, just bury them in your outdoor compost heap.

Patience is required, since the first batch of worm castings cannot be harvested for about two months. However, when you consider that the castings contain between five and ten times more available phosphorus, nitrogen and potassium than the compost you get from your outdoor heap, then perhaps two months is not such a long time to wait! The castings should be added to two parts compost, two parts soil and one part sand. This makes an excellent mixture for potting seedlings. Alternatively, make a `tea' out of the castings and water house plants with it. Happy gardening!

Copyright © Family Matters 1997