August, 2008
The humble worm is a superhero.
Spiralling food prices and global soil depletion are leaving people to starve abroad and making it harder to make ends meet at home. The industrialised world’s response is to massively over-use petrochemical based fertilisers, ship food products all over the world, and send tonnes of unwanted food to fester in landfills.
This wastes nutrients, causes pollution and drives climate change. Enter the worms to save the day. By getting to know your worms, recycling your scraps and adding the result to your veggie patch, you can help solve all these problems at a stroke.
So here’s how to help save the world – one mouldy potato at a time.
Building your worm HQ
When you picture worm farms, you may be thinking of a sprawling, evil smelling, squirming heap. But it needn’t be so. A properly maintained farm does not smell, and these days there are indoor and outdoor worm farm designs to match even the most refined designer tastes.
The scale of your worm farm will depend on the space you have available and how much food waste you want it to deal with. The first thing to do is to work out the average amount of scraps your household generates in a day. Collect all your potential worm food (see below) in a container for one week, weigh it, and divide the weight by seven. This irons out those Sunday blow out fluctuations and the times when you might eat out. Allow approximately 2m² surface area (or a volume of 60 litres) for every 200 grams of food waste per day. Don’t be daunted by the size of your scrap heap. It’s not compulsory to worm farm all your food waste, and every bit helps.
Making the farm as easy and convenient to use as possible will radically improve your chances of success. Consider the location of your worm farm carefully. It should be relatively near the kitchen and/or in a spot which you pass often, so you can drop off food easily and check in on the team. Think about how big it can be if you want to be able to move it without unloading it.
Worms like temperatures between 10 – 25ºC. Ideally, your bin should be in a sheltered spot that gets some sun. You will need to ensure it doesn’t get too hot, and insulate it well if it is outside in colder seasons, otherwise the may freeze to death. Old carpet on top of the contents is ideal for this.
Commercial worm contraptions are on the market for around $150, but it’s more creative looking for a container and converting it for the purpose. Old bath tubs are perfect as they are a good size and come complete with drainage. Old recycling bins, where they have been replaced with newer models, are also good, but wooden containers are better as they provide good insulation and have the added benefit of absorbing excess moisture.
Worms need to breathe, and like to work near the surface. Your warm farm needs to remain damp, but not waterlogged. Whatever you use should only be 20 – 40 cm deep with a relatively large surface area (about 40×40 – 60 cm). Also, if your farm is too deep it can prevent the necessary air getting in and make it awkward to work on. A shallow container also allows for better aeration of the bedding.
Depending on size, drill or punch eight – 12 holes about 10mm diameter in the bottom of the container for aeration and drainage. If contents become too wet, drill more holes. Raise your container up on bricks or wooden blocks to aid air circulation and drainage. Place a tray underneath to capture the excess liquid. It can be diluted one part juice to 10 parts water to make an excellent liquid plant fertiliser. Worms do their thing in the dark, so you will also need a cover, but one which does not seal out the air. This preserves moisture and prevents scavenging animals from tearing through your scrap collection. Weighted down corrugated iron is a popular and effective option.
It’s not hard getting the staff these days. Two species are especially suited for worm composting, Tiger Worms (Eisenia fetida) and Red Worms, (Lumbricus rubellus) also known as red wriggler or manure worms. For each 400 grams of food waste you will need between 500 grams – 900 grams of worms. That’s between 1,000 and 2,000 of the little fellas. But don’t worry, you can always start small, and wait for them to breed. In the ideal conditions they will double their number every 40 days or so.
The easiest way to start your crew is to buy worms direct from specialists. You can find them on Trade Me and in the Yellow Pages. 1,000 worms cost about $30, but some council run schemes offer them at a discount. A cheaper, more fun, but more haphazard way is to collect them from mature manure heaps. Or if we want to economise and socialise you can get some from a fellow worm farmer. Members of Permaculture in New Zealand (www.permaculture.org.nz) are good people to try. You can pick up your worms and pick the experts’ brains at the same time.
To bed your worms down, tear or shred paper, make it damp and add it to your container with a little soil until it is 10-15cm deep. This layer shouldn’t be too wet – it is there to help air circulate. Then load in your worms and the appropriate amount of food scraps, and your planet saving work has begun!
Worms prefer their meals crushed up as small as you can be bothered. They ‘don’t do spicey’, garlic or onions. Other than that they will eat most kitchen vegetable/fruit scraps or peelings, shredded paper, tea bags and leaves, coffee grounds and filters, crushed egg shells, bread scraps, leftover cereal, cottage cheese, plate scrapings, biscuit crumbs, even ice cream.
Avoid adding too much left over citrus or acidic fruits, like oranges, lemons, grapefruit and kiwifruit. These make conditions too acid for the worms. Deal with garden waste in a normal composter – otherwise the heat can kill your wriggly friends. Meat/fish scraps can only be included in moderation and should be buried (not too deeply) in the bedding to stop odours and discourage flies. Also avoid adding oils, as they turn things to slime. It can help the process to add a little semi-mature compost once it is past the heating stage, or aged horse manure. The micro-organisms they contain help soften up the waste for the worms, as well as providing additional food.
If your worms end up eating their own castings, they will die. So your worm farm will need refreshing about once every three months. If you have a suitably large container, you can make this easier from the outset by feeding the worms at only one end of the bin for at least a week before clean-out time. Then take the bedding/castings out of the unfed end of the farm and add it to your garden. (This will remove about half to two thirds of the material and some of the worms.) Place the remaining material in a separate container while you clean the bin and add new bedding. Then replace it and add some scraps. The worms will move out of the old bedding in a couple of days, ready for next time.
You can put the castings you remove from your worm farm, and the diluted liquid fertiliser, directly on your garden. Watch it grow, eat the contents, put the scraps in your worm farm. Repeat.