Compost worm farms

compworms.jpg For organic gardeners who don’t have enough recyclable waste for a productive compost heap, a compost worm farm is the answer.

Compost worms are different from earthworms that tunnel through soil and move into compost heaps after organic matter has been partly processed by microorganisms. Consequently, the term ‘compost worms’ can be confusing to new gardeners. Worm farm (compost) worms require a moister and cooler environment than earthworms (10–30° C.), and feed on a wide range of organic matter, including vegetable and fruit waste (except for citrus and onions), wet paper and cardboard, grass clippings, aged cow and horse manure, soft weeds and hair. Chopping waste into small pieces provides a larger surface area for worms to feed on and speeds up production. The digested waste (worm castings) are a clay-like humus that contains all the nutrients and trace elements that plants need for good health in a form that plant roots can absorb immediately.

Worm castings are Nature’s slow-release, complete organic fertiliser. The more varied the worms’ diet, the better the fertiliser. Simply rake the worm castings into the topsoil on garden beds. As they do not smell, they are the perfect fertiliser for both indoor and outdoor pot plants. They are also a great addition to seedling mixes and, when diluted to very weak black tea strength, the liquid that drains from the worm farm is a fertiliser that gets seedlings off to a flying start.
Worm farming has become a very popular method of recycling and various commercial worm farms are available to suit different situations. Most children find worm farms fascinating and enjoy looking after them.

  • Commercial worm farms come with complete instructions, a starter colony of worms and edible bedding for the worms. Small commercial farms with several tiers are easily moved into a shed or garage in areas where frosts occur. Or, in frost-free areas, if you can find an old hip bath or large sink, you can make your own worm farm as we have here. Worm farming
  • Containers with a drainage hole prevent moisture build up in the base of the farm and a waterproof cover excludes light and rain. (Avoid using old carpet or underlay as a cover as these are impregnated with pesticides.)
  • Add a little water to the farm when necessary to keep the food and bedding damp.
  • A light dusting of dolomite every few weeks will keep the worm farm smelling sweet and the pH close to perfect.

HARVESTING WORM CASTINGS
Worms in farms with stacked trays will move up into the next highest layer when all the food in their tray has been eaten, and it is time to collect the worm castings.
Uncover the worm farm and leave the surface exposed for 15-20 minutes. The worms will move down through the castings away from the light. The castings will contain worm eggs. These are easily recognised as you can see in the photo. They are about the size of the head of a match, or a little bit smaller. Worms don’t lay their eggs in groups like some insects do. They lay them one at a time through the worm castings, but usually close to where they can find food when they hatch.
Harvestcastings1 Use a scoop to collect a layer of castings from the top of the farm. A scoop can be made from a 2 litre juice bottle with a handle. Spread the castings onto an old tray by lightly brushing the castings with gloved hands. Check for worm eggs and any small worms that might still be in the castings and put them safely back into the farm. Cover them with a layer of food.
Then tip the collected worm castings into a bucket and collect another scoop full of castings until you have enough to put into your garden bed, or to make ‘worm tea’.

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