Composting for Beginners: Turn Kitchen Scraps Into Garden Gold

Composting is managed decomposition — creating the optimal conditions for bacteria, fungi and invertebrates (primarily worms and beetles) to break organic matter down into humus: a stable, nutrient-rich, dark brown material that dramatically improves soil structure and fertility.

The process requires four inputs in the right balance:

1. **Carbon-rich 'browns':** Dry leaves, cardboard, paper, straw, wood chips, sawdust (from untreated wood) 2. **Nitrogen-rich 'greens':** Vegetable scraps, fruit peelings, fresh grass clippings, coffee grounds, fresh plant prunings, animal manure 3. **Water:** Compost should be as moist as a wrung-out sponge — not dripping, not dry 4. **Oxygen:** Regular turning or aeration allows aerobic bacteria (the fast, efficient decomposers) to work

The carbon-to-nitrogen ratio ('C:N ratio') is the key variable. Too much carbon (all browns) and decomposition is very slow. Too much nitrogen (all greens) and the pile becomes slimy and smells of ammonia. The ideal ratio is approximately 25–30:1 carbon to nitrogen by weight.

**Hot composting (fast method, 4–12 weeks):** Requires a minimum volume of 1 cubic metre to generate sufficient heat (55–70°C at the core). At these temperatures, weed seeds and pathogens are destroyed. Build the pile all at once with a good green/brown mix. Turn every 3–7 days to maintain oxygen and redistribute heat. This is the method used by gardeners wanting compost quickly and reliably.

**Cold composting (slow method, 6–18 months):** Simply add materials as they become available. No turning required. Slower, but produces excellent compost with zero effort. The best approach for most home gardeners who don't have large quantities of material available at once.

**Types of compost bins:** • Open wire bin: cheapest, good airflow, best for hot composting • Plastic Dalek-style bin: good for cold composting in small gardens, retains moisture and heat • Wooden slatted bin: aesthetically attractive, good airflow, easy to turn • Wormery (vermicompost): ideal for small spaces and kitchen scraps specifically — worms produce very concentrated compost ('worm castings') rapidly

**YES — add these:** • Vegetable and fruit scraps (including citrus in moderation) • Coffee grounds and paper filters • Tea bags (remove staples; check they're not plastic-mesh) • Eggshells (slow to decompose, but add calcium) • Garden waste: grass clippings, plant prunings, dead leaves • Cardboard (torn into small pieces), newspaper, paper bags • Hair and nail clippings • Wood ash (in small amounts — raises pH, adds potassium)

**NO — avoid these:** • Meat, fish and bones (attract pests, putrefy anaerobically) • Cooked food or oil (pest attraction) • Diseased plant material (may survive and spread) • Dog, cat or human faeces (pathogen risk) • Glossy/coated paper or cardboard (contains chemicals) • Perennial weed roots or weed seeds in cold composting (they may survive) • Anything treated with persistent herbicides

**'My compost smells like ammonia or rotting eggs'** Cause: Too many greens (nitrogen-rich), not enough airflow. Solution: Add more browns (torn cardboard, dry leaves). Turn the pile to introduce oxygen.

**'My compost isn't breaking down — it looks the same after months'** Cause: Too dry, too much carbon, or pile is too small. Solution: Water the pile until it's moist like a wrung-out sponge. Add fresh greens (kitchen scraps, grass clippings). If the pile is under 1m³, consider combining two piles.

**'I have pests (rats, flies) in my compost'** Cause: Cooked food, meat, or oil has been added. Solution: Remove any offending material. Ensure the bin has a solid base or sits on hardware cloth. Use a pest-resistant enclosed bin. Only add raw vegetable and fruit scraps.

**'My compost is wet and slimy'** Cause: Excess nitrogen (too many greens) and possibly compaction. Solution: Add large quantities of torn cardboard or dry leaves. Turn to aerate. In very wet climates, cover the pile to prevent excessive rain saturation.