Composting food waste reduces the volume of waste that goes to landfill and contributes to methane emissions, and obviously generates compost for garden use. A wormery is a composting system (“vermicomposting”) to which worms are deliberately added. The worms speed up the composting process by aerating the material, increase the levels of nutrients in the compost [1] and also produce worm “juice” or “tea”, which is a natural fertiliser when diluted [2].
Wormeries can be set up at any time outside, like any compost bin, or somewhere inside with fairly stable temperature and out of direct sunlight, as they are clean and will only produce bad odours if too much food is put in at once [3]. They can be bought from suppliers, or made at home. The worms require very little; they will eat up to half their own body weight every day, double their population every 60-90 days and can be left unattended for up to six weeks [3].
There are many options for building a DIY wormery using recycled materials such as preservative-free wood, an old dustbin or even 3-4 old car tyres lined inside with newspaper [4, 5, 6], but as an example a simple option is to use 3 old plastic crates that will stack onto each other, such as spare recycling boxes:
- Drill lots of small holes around the tops of the boxes and in the lid, for ventilation [7]
- Drill a hole near the base of the box that will be the lowest in the wormery and fit a water butt tap to it to extract the worm tea from. Raise the whole system on bricks or blocks to make the tap easy to access [4, 8]
- Use gauze on the inside of the ventilation holes to prevent flies getting in and worms escaping [5, 8]
- Drill holes in the bases of the upper two boxes, or cut the bases out and replace them with wire mesh [5], for drainage and to allow the worms to move between the layers
- Put a layer of stone chippings or sand in the lowest box, to aid drainage and prevent any worms that get into the bottom layer from drowning [5, 9]
- Then put the middle box on top of the base, and add a layer of bedding. This can be made of materials such as shredded newspaper, corrugated cardboard, leaf mould, compost, sawdust or wood chips, and needs to be damp [10, 11]. A small amount of soil can be added to help the worms adapt to their new environment [3]
- Add at least 100 composting worms to the bedding. These are often called red or tiger worms and can be bought from various sources or taken from another wormery. Never use worms from the garden as they require different conditions [5, 9, 12]
- Put the last box on top of the wormery, cover it with the lid, and leave the worms to acclimatise for a few days [5]
- Then add food to the middle box and allow the worms to compost it – when the middle box is full, start adding waste to the upper box and when the middle box has been composted, remove it, empty it and then put it back on top of the wormery. The worms should have fully composted the bedding material within about 8 weeks [11]
Other styles of wormery will be constructed and operate in a similar way. There are many websites offering plans and advice for building and maintaining wormeries. Common tips include:
- Don’t overfeed the worms [3]
- Drain the system regularly [5]
- Generally the same food guidelines apply as with any compost bin, e.g. avoid meat and dairy foods, plus acidic food waste such as citrus fruits [12]
- Grass cuttings should also be avoided as they heat up to an unsuitable temperature – 12-25 oC is the ideal temperature range for worms [12]
- Small pieces of food will be easier for the worms to digest [9]
- The bin should not be allowed to dry out – water can be added if necessary [9]
- If the wormery is kept outside, insulate it during winter (e.g. with bubble wrap, or move it into a shed or garage) [3]
- Dilute worm tea with 10 parts water to use as plant feed [12]
Using compost and plant feed produced by worms increases the amount of nutrients reaching plants and cuts down on resources and energy used to produce, package and transport commercial compost and feeds, as well as reducing pollution from artificial fertilisers. Wormeries can be more convenient than large compost bins, as they produce compost more quickly and don’t require a garden, so are ideal for producing compost and feed for potted plants and window boxes.
[1] http://www.franklincountywastedistrict.org/vermicomposting.html
[2] http://www.worcestershire.gov.uk/cms/communications/news/2010/february/diy-wormeries.aspx
[3] http://www.wormcity.co.uk/wormfaq.htm
[4] http://www.letswasteless.com/cms/default.aspx?page=7423
[6] http://www.easthants.gov.uk/ehdc/recyclingandwaste.nsf/webpages/Wormeries
[8] http://www.wormery.co.uk/how-to-make-wormery.htm
[9] http://www.dorsetforyou.com/wormeries
[10] http://gardenwormeryguide.com/how-to-build-a-wormery-part-1/
[11] http://www.newcastle.gov.uk/environment/rubbish-waste-and-recycling/building-your-own-wormery
[12] http://www.letstalklessrubbish.com/CHttpHandler.ashx?id=13674&p=0
