How to Compost

4 types of compost bins. Which type suits your need?

“Turn waste into fertiliser and save the planet, by composting!”

Composting is the breaking down of organic matter, in a controlled environment, into humus, which is rich organic fertiliser (the same kind that takes years to build up in forest systems!). Composting at home is easy, and it can turn waste from your kitchen and your yard, into enough fertiliser to grow all the food you need.

Benefits:

  • Saves the planet!
  • Saves water
  • Recycles waste
  • Creates organic fertiliser

Materials:

  • A large bin or some wire mesh.
  • All compostable materials: Food scraps, eggshells, leaves, weeds, prunings, newspapers, cardboard (plain), seaweed, grass clippings, hay/straw, manure.

Jump to:

What is Thermophilic Composting?
Batch Composting versus Continuous Composting
Compost Bins
Gathering Materials
Starting a Compost Pile
Adding to a Compost Pile
Turning a Compost Pile
Monitoring a Compost Pile
Watering a Compost Pile
Allowing Compost to Cure
Using Finished Compost
FAQ
Why compost?
What are the alternatives to composting?
How long until I get finished compost?
Why isn’t my compost heating up?
Why does my compost pile smell bad?
Why are there bugs in my compost?
What about rats and other animals?
What about Legionnaires’ disease?
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Tumbler Composting
Cardboard Compost Bins
Human Waste Composting

What is Thermophilic Composting?

A compost thermometer reading 135degF, which is a hot composting (thermophilic) temperature

A compost thermometer reading 135degF, which is a hot composting (thermophilic) temperature.

The activity of bacteria in a compost pile produces heat, so for as long as the centre of your pile is warm you’ll know your composting is working. Thermophilic composting occurs when the temperature in your pile exceeds 45degC (113degF). It’s a desirable phase of composting because weed and grass seeds are destroyed, along with plant diseases and even human diseases. It is also a very fast phase of composting, breaking down materials in days, but it is usually short-lived, and a slower (mesophilic) phase takes over.

Batch Composting versus Continuous Composting

You will have to choose which method of composting is best suited to you. Batch composting is when you save up all your materials until you have enough to fill a bin or make a complete pile. Continuous is when you add materials gradually to a bin or pile. Both methods enable thermophilic composting, and both produce the same compost. If you’re building a compost pile or using a large bin, I recommend starting a continuous composting operation. If you’re using a small bin or a compost tumbler I recommend batch composting.

Compost Bins

Different compost bins suit different people. Try them all!

Compost bins come in many shapes and forms, and can be made out of just about anything. They keep the materials together, and allow air to penetrate the pile.

  • Plastic compost bins keep light out and prevent moisture evaporating out of the pile.
  • Pallet-style bins can hold a large amount of material, and can be made for easy access.
  • Cardboard compost bins are the cheapest way to go (free).
  • Wire mesh compost bins are cheap and can be made to be taken off and reused when turning a pile or making more piles.
  • Compost tumblers allow for batch composting without the effort of turning. They’re also rat-proof.

I recommend starting with a cardboard compost bin, using the continuous composting method, and advancing from there.

Gathering Materials

Kitchen scraps, grass clippings, eggshells, old vegetables, mouldy bread, newspapers, weeds and even charcoal are all good ingredients for composting

Kitchen scraps, grass clippings, eggshells, old vegetables, mouldy bread, newspapers, weeds and even charcoal are all good ingredients for composting

  • Gather your kitchen scraps in buckets. If you notice bad smells, try using bokashi to preserve them and eliminate the odour. This may become important if you’re saving up enough material for batch composting.
  • As you remove weeds, prune plants and trees, and harvest produce in your garden, collect all the waste materials. There’s no need to let them dry out – it doesn’t matter.
  • If you have lawn mowed, ask the lawnmower man for some of the grass clippings. They are an excellent ingredient for composting, and they will otherwise be discarded in landfill.
  • In Autumn (Fall) collect fallen leaves. Store them in a bin ready for composting. Don’t worry if they begin to break down – that’s the idea anyway!
  • Set aside newspapers and plain cardboard (not the glossy stuff). These are made from wood pulp, and make for an excellent addition to your compost pile.
  • If you like to take strolls on the beach, take a bucket and fill it with seaweed as you go. Seaweed is a plant material which has all sorts of minerals and nutrients from the ocean which might not be so abundant in your soil (or in your food). Introducing a bit of seaweed ensures you are building up fertility with a rich compost.
  • If you keep chickens and use a natural bedding (hay/straw/shredded newspaper), collect this along with any chicken manure. Chicken manure helps to heat compost.
  • As a last resort, if you find you don’t have enough of either hay/straw, weeds, prunings, leaves or grass clippings to bulk up your compost, consider purchasing ‘spoilt hay/straw’ from a local farm/garden supplier. It is hay/straw that has either gotten wet or has broken out of its bale string. It’s a perfect compost material, and is cheap.

Starting a Compost Pile

If you’re using a compost tumbler, you can empty all your materials into it, in any order, then tumble to mix them thoroughly. If you’re building a pile in a bin, you will need to add your materials in layers.

  • Start your pile with some of the bulkiest material you have – hay/straw, twigs, branches, leaves, cardboard (shredded coarsely). Having bulky material at the bottom will allow air to get in underneath the pile.
  • Into the centre of the pile add all your other materials, one at a time or bit by bit so that they’re mixed. Don’t worry if any of them are rotting or smelling bad – you can still add them to the pile.
  • I recommend adding a few handfuls of soil to your pile. Soil brings with it all kinds of bacteria, and it will mean that your finished compost will have a soil content, which plant roots enjoy grabbing onto.
  • Cover your pile with either hay/straw, leaves, newspaper (shredded) or grass-clippings. This acts as a cover material, keeping sunlight out, moisture and odours in, and allowing air to penetrate the top of the pile.

Your compost pile should heat up within a few days.

Adding to a Compost Pile

If you’re using a compost tumbler, I recommend batch filling it and not adding any further material to it (this will interrupt the thermophilic phase). When you’re adding to a pile, it’s best to add to the centre, where the pile is most active.

  • Using a pitch-fork, pull the cover material away from the top centre of your pile, toward the walls of the bin. This now becomes an insulator around the outside of the pile – letting air in, but retaining warmth and moisture.
  • Dig into the centre of the pile with your pitch fork, pulling back toward the walls to create a hollow. You should find the material in the centre warm or hot, with no bad smells.
  • Add your fresh materials into the hollow, one at a time or bit by bit so that they are mixed.
  • Cover the pile with hay/straw, leaves, newspaper (shredded) or grass-clippings.

Each time you dig into your pile to add fresh material, you are allowing air to penetrate right where the bacteria need it most – the centre. Following this method, you should not have to turn your pile.

Turning a Compost Pile

If you’re using a compost tumbler, turning is as simple as spinning the tumbler a few times to remix the materials and allow fresh air into the mix. If you’re continuously composting in a pile (as explained above) you won’t need to turn at all. If you’ve decided to batch compost in a bin/pile, you will have to turn your pile, to remix and re-oxygenate the materials.

Bacteria in your pile require oxygen to do their work, and in the centre of your pile – where bacteria are most active – oxygen is in high demand. With materials collapsing as they break down, passages for air begin to block and oxygen runs out. This creates the perfect environment for anaerobic bacteria – the kinds which produce acids, alcohols and awful smells – who take over and turn your pile into a putrid mess! As you might imagine, it’s best to turn your pile before it becomes anaerobic.

You can try using your pitchfork to turn your pile while it’s still inside the bin, by taking material from the centre to the edges, and material from the edges to the centre. It’s by no means an exact method, but it might be all the effort you’re willing to expend.

For serious batch composters, turning is an opportunity to regain thermophilic temperatures after they’ve initially subsided, and turning well is important. Some use a series of bins, and scoop material from one into the next. Others use a wire mesh bin, which can be detached from the materials and placed next to it, and the materials are then scooped into the mesh again. Both systems turn materials effectively.

Monitoring a Compost Pile

When you’re starting out with composting, there are a few things to look for as tell-tail signs that everything is going well, or that you might need to intervene.

Temperature

How hot your pile is will tell you how active bacteria are in the pile. The hot (thermophilic) phase might last a week or two, then different organisms take over and a warm (mesophilic) phase ensues. Stick a stick into the centre of the pile, wait a minute, then pull it out and feel the temperature.

Smells

Active compost shouldn’t smell bad.

  • A rotting smell means oxygen is not getting into the pile – turn/tumble it.
  • An ammonia smell means there’s an excess of nitrogenous material (such as grass-clippings or chicken manure). This won’t hurt your compost, but is a waste – as a lot of nitrogen is leaving the pile as ammonia gas. Shred some newspaper or cardboard in there to mellow it out.
  • A dank smell means there’s an excess of carbonaceous material (such as newspapers or cardboard). This won’t hurt, but you won’t achieve thermophilic temperatures with this mix. Try adding grass-clippings or chicken manure to get it cooking.

Moisture

Bacteria needs moisture, but only dampness. A sopping wet compost pile will likely turn anaerobic. A dry compost pile will not break down. Check around the edges. If it’s bone-dry, water just around the edges.

Watering a Compost Pile

Food scraps are about 90% water, and there’s a water content to most things you add to your compost. There should be enough there to keep bacteria happy and working. If you’re using a compost tumbler, watering should not be necessary unless ALL of the material appears dry, and in such cases only a few seconds of watering, followed by thorough tumbling will dampen the materials sufficiently. In a compost pile, water is lost first from the edges, and rarely from the centre. If the edges of your pile are bone-dry, water around the edges.

Allowing Compost to Cure

Composting takes time, but after the first few weeks of intense activity, you don’t need to do anything with the materials. Fungi, bacteria, worms and other organisms will continue to digest and convert materials in your pile, into cured compost. In a well managed, batch built compost pile which has achieved and sustained thermophilic temperatures for at least a week, the material can have finished breaking down within 3 months. For other operations it’s best to allow 6 months from your last addition to the pile, for the compost to be cured and ready for use.

Using Finished Compost

Finished/cured compost should appear black, with a crumbly texture, and smell like fresh earth. You should not be able to distinguish any of the original materials, and it should not be hot.

Empty your compost into a wheelbarrow, and take it around your yard. Spread a 1inch layer around plants and trees, and over garden beds that you plan to grow in. You can dig compost into the soil, but unless your soil is compacted clay, digging in is not necessary and even destructive to soil biology. On the surface it will act as a mulch and slow-release fertiliser, and will eventually find its way into the deeper soil. Cover over your soil with mulch for best results. With continuous applications of finished compost, your soil will become among the healthiest in the world!

Frequently Asked Questions

Why compost?

Composting is a great way to turn waste materials into organic fertiliser. By learning how to compost, you can recycle all your organic waste, and grow all the food you need. While you’re busy creating abundance in your garden, you’re saving the world from landfill pollution, and the energy and environmental cost of commercial and chemical fertilisers.

What are the alternatives to composting?

Worm composting or worm farming is an effective alternative to composting. Worms will eat most of your kitchen scraps and turn them into rich vermicompost (worm poo!) which can be used in your garden just like compost. Worms can’t handle woody materials, ‘hot’ materials like grass clippings and chicken manure, and they’re not keen on onions and garlic, but they can tear through cardboard and newspaper quicker than any thermophilic compost pile!

Burying your waste is a cheap and nasty alternative to composting. In the ground, the material will quickly go anaerobic, and will mostly be broken down by anaerobic bacteria, which produce acids and alcohols and turns everything putrid. Try digging it up after a week and you’ll see what I mean!

Bokashi composting is a better way to bury waste. Bokashi added to your scraps ferments them, and prepares them for a quick breakdown in the soil. Some acids are still involved, but nothing the soil biology can’t regulate.

Biogas can be produced from your food waste, in a biogas digester. The gas is collected and used for cooking, and the liquid that comes out of the digester is a wonderful liquid fertiliser.

How long until I get finished compost?

It’s best to set aside 6 months from when you finish adding to your compost pile, for your compost to finish curing. Experienced composters will maintain a hot (thermophilic) phase for as long as two weeks, which is an accelerated phase, and may only need to wait 3 months before their compost is ready. While you wait, I suggest to start a new pile!

Why isn’t my compost heating up?

You have not created the right environment for thermophilic bacteria to operate. They need food (a good mix of different materials), moisture (damp, but not sopping wet), oxygen (air must be able to penetrate to the centre of your pile) and time. A good mix of materials should heat up within a few days.

Why does my compost pile smell bad?

A well-built compost pile, in a well-managed composting operation should not produce bad smells. Bad smells are the result of anaerobic bacteria at work in the pile, and are an indication that not enough oxygen is getting into the pile. It could be too wet (it should only be damp, not sopping wet) or it could have collapsed, blocking passageways for air. Hold your breath and turn the pile, shifting material from the centre to the edges, and material from the edges to the centre. This will re-oxygenate the pile, and redistribute moisture.  If it’s too wet, add shredded newspaper or shredded cardboard as you turn. Check your pile every few days and repeat if it happens again.

Why are there bugs in my compost?

Those bugs are playing various roles in the breakdown of your materials. As they grow, eat, reproduce and die, so your compost becomes enriched with a diversity of organic residues. Worms, slaters, slugs, earwigs, cockroaches, ants and aphids are all common helpers in compost piles. Concentrate on keeping your compost damp and covered, and leave the bugs to do their thing!

What about rats and other animals?

Rats are attracted to the conditions around the outer edges of a compost pile (where it’s warm and safe), and to any fresh food scraps in the pile. Animals like dogs and chickens can decimate a pile out of curiosity or for the worms and bugs.

If rats are an issue, I suggest using a compost tumbler, which is sealed.

To keep out chickens and dogs, cover the pile with some wire mesh.

What about Legionnaires’ disease?

Legionella bacteria (of which only a few strains can cause harm to humans) thrives in warm moist conditions, including compost piles/bins. Of those exposed, legionella affects only 2-5% of people. Exposure happens when you breathe in dust or vapour from a contaminated compost pile.

If you’re elderly or have a weakened immune system, consider wearing a mask when working with your compost. Also, if your compost is dry, wet it before turning or digging into it (this will prevent dust kicking up).

A compost pile is a place full of bacteria and fungi. Using gloves and washing hands thoroughly is always recommended.

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