The Ultimate Guide to Composting: Turning Garden Waste into Nutrient-Rich Soil

Introduction

Composting is one of the most effective ways to recycle organic waste and create nutrient-rich soil for your garden. By setting up your own compost system, you can reduce landfill waste, improve soil health, and promote sustainable gardening practices. Whether you have a backyard, a small garden, or even a balcony, there’s a composting method for you.

Compost is decomposed organic material that enriches the soil by providing essential nutrients to plants. It improves soil structure, increases moisture retention, and supports beneficial microbes. Composting is a natural process that turns kitchen scraps, garden waste, and other biodegradable materials into a valuable soil conditioner.

Benefits of Composting:

• Reduces household waste
• Enhances soil fertility
• Supports water retention in garden beds
• Reduces reliance on chemical fertilisers
• Helps fight climate change by reducing methane emissions from landfills

Different composting methods suit different spaces and needs. Below is a comparison of common composting methods to help you choose the best option for your home or garden:

Essential Tools

To make composting easier and more efficient, consider using the following tools:

• Pitchfork or Garden Fork: Useful for turning and aerating your compost pile. 
• Shovel: Helps add and mix materials into your compost heap.
• Compost Thermometer: Measures the temperature of your compost to ensure optimal decomposition.
• Garden Gloves: Keeps hands clean and protected while handling compost.

Browse our Gardening Tools category for more options.

Select a spot that is shady, well-drained, and has good airflow. Avoid placing the compost heap in direct sunlight, as it can dry out too quickly. If possible, set it on bare soil to allow worms and beneficial microbes to assist in decomposition.

Start with a layer of coarse material like small branches, twigs, or straw. This helps with aeration and drainage, preventing the pile from becoming too compacted.

To maintain a balanced compost heap, alternate layers of:

• Greens (Nitrogen-rich materials): Fruit and vegetable scraps, grass clippings, coffee grounds.
• Browns (Carbon-rich materials): Dry leaves, cardboard, shredded newspaper, straw.

Aim for a ratio of roughly 2 parts browns to 1 part greens to ensure efficient decomposition.

The compost pile should be damp but not waterlogged. If it feels too dry, sprinkle it with water. If it becomes too wet, add more brown materials to absorb excess moisture.

Aerate your compost heap by turning it every 1-2 weeks with a pitchfork or shovel. This speeds up decomposition and prevents unpleasant odours.

Check your compost pile regularly for moisture, balance of materials, and progress. If it has a strong odour, add more browns. If it’s decomposing slowly, introduce more greens and aerate it more frequently.

After a few months, your compost will be ready when it turns dark, crumbly, and has an earthy smell. Use it as mulch, a soil conditioner, or mix it into garden beds for healthy plant growth.

To learn how to use compost as mulch, read our mulching guide.

Achieving the right mix of nitrogen and carbon materials is essential for efficient composting.

• Fruit and vegetable scraps
• Grass clippings
• Coffee grounds
• Tea bags
• Fresh leaves

• Dry leaves
• Straw
• Shredded newspaper
• Cardboard
• Sawdust (untreated wood only)

Avoid: Meat, dairy, oily foods, diseased plants, and pet waste.

• Aeration: Turn the pile regularly to introduce oxygen and speed up decomposition.
• Moisture control: The pile should feel like a damp sponge; add water if too dry and more browns if too wet.
• Compost accelerators: Use natural activators like manure, seaweed, or Mitre 10’s compost starters.

• Smelly compost? Too wet or too much green waste. Add more browns.
• Pile not breaking down? Too dry or not enough nitrogen. Moisten and add more greens.
• Pests in the bin? Avoid food scraps that attract rodents. Use a secure compost bin.

• Compost is ready when it’s dark, crumbly, and has an earthy smell. It can take anywhere from 2 months to a year, depending on conditions.

• Mulching: Spread a layer around plants to retain moisture.
• Soil amendment: Mix into garden beds for added nutrients.
• Potting mix: Blend with soil for container plants.

Explore garden soils and potting mixes for your compost-enriched soil.

Hot composting is an accelerated method that rapidly decomposes organic waste by maintaining high internal temperatures (above 55°C). This method requires a well-balanced mix of nitrogen-rich greens and carbon-rich browns, frequent turning, and careful moisture management.

Pros:

• Produces compost in as little as 4-8 weeks.
• Kills weed seeds and pathogens due to high temperatures.
• Reduces odours compared to slow composting.

Cons:

• Requires regular monitoring and turning.
• Needs an optimal balance of greens and browns to sustain heat.

Compost tea is a liquid fertiliser made by steeping mature compost in water, often aerated to promote beneficial microbial activity. It provides a quick nutrient boost for plants and improves soil health.

1. Fill a bucket with water (preferably rainwater or dechlorinated tap water).
2. Place a mesh bag filled with mature compost into the bucket.
3. Let it steep for 24-48 hours, stirring occasionally or using an aerator.
4. Strain and use the liquid to water plants or as a foliar spray.

Pros:

• Enhances plant growth with beneficial microbes and nutrients.
• Can be used as a natural pest deterrent.
• Reduces fertiliser dependency.

Cons:

• Requires aeration for best results.
• Short shelf life (must be used within 24 hours of brewing).

Biochar is a type of charcoal that enhances soil structure, retains moisture, and improves microbial activity when added to compost. It’s created through pyrolysis, a process of burning organic material in a low-oxygen environment.

1. Crush biochar into smaller pieces for better integration.
2. Mix biochar into your compost pile at a ratio of about 5-10% of total compost volume.
3. Let it absorb nutrients before applying it to soil.

Pros:

• Improves soil aeration and water retention.
• Sequesters carbon, reducing greenhouse gas emissions.
• Enhances microbial life in compost and soil.

Cons:

• Can be expensive or time-consuming to produce.
• Overuse may temporarily lock up nutrients in the soil.

It depends on the method, materials, and conditions. A well-maintained pile can be ready in 2-6 months.

Can I compost in winter?

Yes! Decomposition slows down, but turning the pile and adding greens can keep it active.

Worm farms and bokashi bins work well for apartments and balconies.

Yes, but in moderation. Citrus and onions can be slow to break down and may deter worms in vermicomposting. Cutting them into smaller pieces can help speed up decomposition.

A strong odour usually means there is too much moisture or too many nitrogen-rich materials. Turn the pile and add more carbon-rich browns like dry leaves or cardboard to balance it out.

Turning the compost helps aerate it, speeding up decomposition and preventing anaerobic (bad-smelling) conditions. However, passive composting without turning is possible but takes longer.

Dog and cat waste should not be added to standard compost piles, as it can contain pathogens. However, specific composting systems designed for pet waste exist.

Use a sealed compost bin, avoid adding meat or dairy, and bury food scraps under a layer of browns to deter pests.

It's best to avoid cooked food in traditional compost piles, as it can attract pests. Bokashi composting is a better option for composting cooked food scraps.

Composting is an easy and rewarding way to reduce waste while improving your garden. By following this guide, you can create nutrient-rich soil to nourish your plants and contribute to a healthier environment. Whether you’re a beginner or an experienced gardener, composting is an excellent way to promote sustainability while enhancing soil fertility.

Beyond just waste reduction, composting supports beneficial microbes, improves plant health, and minimises the need for synthetic fertilisers. With a well-maintained compost system, you can cultivate healthier, more vibrant plants while also doing your part for the environment.

Are you ready to start your composting journey? Check out composting products for essential tools, bins, and organic matter to set up your own nutrient-rich composting system! Happy composting!