Just four ingredients are needed for this recipe for garden food – nitrogen (green material), carbon (brown material), water and air. In the right mix, they’ll attract the micro-organisms essential to speed up decay. If you have room to spare, maintain two heaps – one where the food is cooking, and the second where the cooked humus is good to go.
Combine brown and green material. Brown items include dried plant matter, fallen leaves, shredded branches, cardboard or other paper products, straw and wood shavings. They’re also called ‘dry’ and add carbon to your pile. Green items include kitchen scraps and fresh plant or grass clippings. They’re also called ‘wet’ and add nitrogen. Start your pile by mixing 3 parts brown with 1 part green material.
Add water. Sprinkle your compost regularly with water so it has the feel of a damp sponge. If the pile looks too wet and begins to smell, add more brown items or turn the pile more often. If it looks brown and dry, add green items and water to make it slightly moist. But don’t add too much water or the microorganisms in your pile will drown, and it will then rot instead of breaking down. As the decay progresses, the pile should feel warm. Test it by reaching into the pile with your hand.
Stir often. Add oxygen to your pile by turning it once a week with a garden fork. This will help it cook faster and prevents it from smelling.
Feed your garden. When the compost no longer gives off heat and becomes dry, brown and crumbly, it’s cooked. Add to a depth of about 15cm to your flower and vegetable beds and add to your potting mix in spring.
This is as simple as throwing all your kitchen waste (vegetable and fruit peelings, coffee grounds, eggshells), organic household waste (hair from brushes, clothes dryer lint, coffee filters, pet fur or wool, shredded newspaper), and garden debris into a pile on bare earth or a bin with holes in the bottom so soil creatures can move in – then ignoring it. All these materials will break down over a year and can be spread over or dug into your garden soil.
Tips and tricks
- Compost is the heap breaking down. Humus is the final product – black or dark brown, crumbly and very sweet smelling!
- Cut garden debris into pieces about 12-15cm so it breaks down more quickly.
- Adding humus to your vegie patch increases the water-holding capacity of your soil and puts in nutrients vital for quick-growing plants.
What not to add
- Meat and fish scraps - The smell of rotting fish or meat attracts rats, flies and even household pets.
- Dairy, fats and oils - These also smell and will attract vermin.
- Pesticides or preservatives - Preservative-treated wood and plants treated with pesticides have a chemical residue that can kill composting organisms. This residue can also affect plants after composting.
- Diseased or insect-infested plants - Most compost piles don’t reach the high temps needed to kill pests and diseases, so they’ll survive to infect plants after compost is added to your garden.
- Weed seeds - Weed seeds survive composting, so you’re adding to your weed problem when you put it in your garden.
- Dog or cat waste - Dog and cat faeces can turn compost into hazardous waste, as both carry bacteria and parasites that cause human disease.
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