Photographs Francois Oberholster
Vermicompost (worm fertiliser) is easy to make. Talitha Cherry, horticulturist at Western Cape wine estate Babylonstoren, and Franz and Sue Mentz of Wurmbosch Wormery and Organics outside Stellenbosch explain how it works:
1. What is vermicompost?
Vermicompost is compost made by earthworms from kitchen waste and scrap paper. It’s a popular method of recycling and a simple way to get rid of kitchen scraps. A by-product of the process is worm tea, a liquid fertiliser that is just as good for your garden. Both the compost and the tea are full of nutrients, which is why gardeners commonly refer to vermicompost as “black gold”.
2. What do I need?
All you’ll need is a worm farm (see point 3), kitchen waste (see point 7) and earthworms!
3. Your worm farm
The most popular worm farm basically consists of three containers stacked on top of each other. You can buy a ready-made worm farm at garden centres and co ops or make your own.
- The lower container catches the worm tea so it must be watertight. If this level has a tap, you’ll be able to pour out the worm tea that much easier, but it’s not necessary.
- The middle level is the worms’ ‘factory’ and breeding area. Fill this with kitchen scraps and paper and put your worms here. Drill small holes in the base of this container so that the worm tea can seep down to the lower level. Drill a few tiny holes in the upper half of the middle container for ventilation.
- The top level must be a container with a lid – the lid helps to keep the rain out and stops birds from eating the worms. Make sure the lid also fits the middle container so it can also be sealed when it is swapped with the top container (see point 5). The top container must also have holes in its base so that the worms can move upward from the middle container once they have processed its contents.
4. Which worms?
Worms in a worm farm are not ordinary garden earthworms but their cousins, the red wrigglers (Eisenia fetida). Ask someone who already has a worm farm to give you a few, or search online for your nearest stockist; it will cost about R50 for 200 worms.
5. Where do I start?
- Choose a spot sheltered from the wind, sun and rain. The worm farm can even stand in the garage as it doesn’t have an unpleasant odour.
- Collect kitchen waste in a container and add the contents to your worm farm daily.
- Fill your container in this way: sprinkle a layer of compost, about 5cm deep, at the bottom of the middle container. Add the worms. (If you buy worms, they’ll be supplied with compost-rich soil – add this as well.) Put kitchen scraps on top. The layer of kitchen waste should be no higher than 10cm, otherwise it becomes a mini compost heap and the heat produced by the material will kill off your worms in such a confined space. Add scrap paper such as newspaper, cardboard, egg boxes and empty cereal boxes (tear them into smaller pieces). Paper serves as a breeding area and helps to maintain the moisture content of the farm. Cover the kitchen waste with a sheet of newspaper and lift it up when you add new scraps. Sprinkle a little water on the newspaper to keep it moist. If the contents of your farm dry up, the worms will perish; however, the worm compost must never be waterlogged.
- When the middle container is full, add fresh scraps to the top container; once their food supply in the middle runs out, the worms will move upwards. Make sure that the base of the top container is in contact with the contents of the middle container so the worms can get to the food above. Give the worms a few weeks to move upwards before using the compost from the middle container in your garden. Now swap the two containers so that the middle container is the one in which your worms are active.
6. Ongoing care for your worms
Earthworms preferably need fresh food every day. If you go on holiday, there are several options: simply add lots of food on top of the middle container so that they can continue to eat. If you go away for longer than three weeks, ask someone to feed your earthworms once a week, or leave them to process the waste. They will lay eggs and, once you return, moisten the contents again and add fresh material. The eggs will soon hatch and provide new life!
7. What's on the menu?
- Peels; especially banana peels.
- Salad leaves and raw vegetables, but not too many watery fruits such as watermelon in one go.
- Teabags and coffee grounds.
- Crushed egg shells.
- Herbs; but chop up any hard stems finely.
- Bread (it attracts mice).
- Citrus fruit, garlic, chillies and onions (they don’t like bitter flavours).
- Meat – raw or cooked.
- Dairy products.
Mix your vermicompost with a little garden soil or river sand and plant seedlings in it or use it as a compost supplement in your garden. Mix it with the potting soil when planting up a new pot plant.
Use the worm tea that collects in the lower container as a liquid fertiliser. If you squeeze the vermicompost in your hand, there should only be a few drops of worm tea. If there’s too much liquid, your worm farm is too wet. If the humidity in your farm is just right, the liquid will be the colour of tea, hence the name.