Composting transforms kitchen scraps and garden waste into black gold, the rich, crumbly material that plants love. For Australian gardeners, composting is particularly valuable as it improves our often-poor native soils while reducing waste sent to landfill. This comprehensive guide covers everything from getting started to troubleshooting common problems.
Understanding the Composting Process
Composting is a natural process of decomposition accelerated through careful management. Microorganisms including bacteria and fungi break down organic matter in the presence of oxygen, transforming it into stable humus rich in nutrients and beneficial biology.
Successful composting requires balancing four elements: carbon-rich brown materials, nitrogen-rich green materials, moisture, and oxygen. When these elements are in proper proportion, decomposition proceeds rapidly with minimal odour. Imbalances cause slow decomposition, bad smells, or pest problems.
Temperature indicates composting activity. Active compost heats to between 40 and 65 degrees Celsius as microorganisms multiply. This heat kills weed seeds and pathogens, creating safe, finished compost. Cool compost still works but takes longer and may not eliminate all seeds and diseases.
Setting Up Your Compost System
Choosing the right composting system depends on your space, time availability, and volume of materials. Several options suit Australian conditions and lifestyles.
Traditional compost bins suit suburban gardens with moderate waste volumes. Open-bottom bins allow drainage and earthworm entry while containing materials neatly. Tumbler bins speed decomposition through easy turning but require more upfront investment.
Bay systems work well for larger gardens generating significant organic matter. Three-bay systems allow continuous composting: one bay filling, one cooking, and one providing finished compost. This ensures a steady supply while managing large volumes efficiently.
Bokashi systems suit small spaces or indoor composting. This anaerobic fermentation process pickles food waste including meat and dairy, materials excluded from traditional compost. Fermented material then finishes in garden soil or a traditional compost pile.
Worm farms process food scraps efficiently in limited space. Worm castings are exceptionally nutrient-rich and biologically active. However, worms cannot handle large volumes or garden waste, so they complement rather than replace traditional composting.
What to Compost and What to Avoid
The ingredients you add determine composting success. Understanding what belongs in your compost and what to exclude prevents problems and ensures quality finished product.
Green materials provide nitrogen and moisture. Suitable greens include vegetable and fruit scraps, fresh grass clippings, green plant trimmings, coffee grounds, tea leaves, and fresh manures from herbivores. These materials tend to be wet and decompose rapidly.
Brown materials provide carbon and structure. Use dry leaves, straw, shredded paper and cardboard, wood chips, dried grass, and small prunings. Brown materials balance the wetness of greens and prevent compaction that excludes oxygen.
Avoid adding meat, fish, dairy, and oily foods to traditional compost, as they attract pests and create odours. Diseased plant material may spread problems if compost does not heat sufficiently. Avoid pet manures which can harbour harmful pathogens. Persistent herbicides in some hay and manures damage sensitive plants, so source carefully.
Maintaining Your Compost
Active management accelerates decomposition and prevents problems. Regular attention ensures your compost system works efficiently.
Aim for a carbon to nitrogen ratio of roughly 30:1. In practice, this means adding two to three parts brown material for every part green. When adding kitchen scraps, always cover with a layer of browns to prevent odours and flies.
Maintain moisture like a wrung-out sponge. Too dry and decomposition stalls. Too wet and anaerobic conditions develop, creating bad smells. In Australian summers, you may need to water compost. In wet periods, cover to prevent waterlogging.
Turn compost regularly to introduce oxygen and redistribute materials. Weekly turning accelerates decomposition significantly. Move material from the outside to the centre where microbial activity is greatest. Tumbler bins simplify turning through their rotating design.
Monitor temperature using a compost thermometer or simply by feel. Hot compost indicates active decomposition. If temperatures drop before materials are finished, add nitrogen-rich greens or turn to reactivate the process.
Troubleshooting Common Problems
Even experienced composters encounter occasional problems. Quick identification and correction gets your compost back on track.
Bad smells usually indicate anaerobic conditions from too much moisture or insufficient oxygen. Add brown materials to absorb excess moisture, turn to introduce air, and ensure drainage is adequate. Ammonia smells suggest too much nitrogen; add browns to balance.
Pests like flies result from exposed food waste or meat in compost. Always bury fresh additions under brown material. Rodents suggest inappropriate materials or easy access; ensure bins are secure and avoid adding cooked food or bread.
Slow decomposition indicates missing elements. Add greens if the pile is dry and inactive. Add moisture if materials are too dry. Chop materials smaller to increase surface area for microbial action. In cold weather, insulate piles or accept slower processing until temperatures rise.
Using Finished Compost
Finished compost is dark, crumbly, and smells earthy. Original materials should be unrecognisable. If chunky pieces remain, screen them out and return to the active pile for further decomposition.
Apply compost liberally throughout your garden. Dig into new beds during preparation, or spread as a surface mulch around established plants. Use our Material Calculator to determine how much compost you need for your garden beds.
Compost improves all soil types. It opens heavy clay, improving drainage and aeration. It bulks sandy soil, increasing water and nutrient retention. The biological activity in compost supports healthy soil ecosystems that benefit plant growth.
Make compost tea by steeping finished compost in water for a nutrient-rich liquid fertiliser. Use immediately on plants for a quick boost during the growing season.
Composting closes the loop in sustainable gardening, turning waste into valuable resource. By maintaining your own compost system, you reduce landfill waste, save money on purchased amendments, and create the foundation for a thriving Australian garden. Start your composting journey today and discover the satisfaction of creating your own black gold.
Ready to Plan Your Garden?
Use our free garden calculators to determine exactly how many plants you need and how much material to order.
Try Our Free Calculators