How to Make Compost
Any gardener can benefit from adding nutrients and organic matter to the soil to help plants thrive. One of the most beneficial substances you can add is homemade compost. Whether your garden is indoors or outdoors, compost can help all your plants grow better.
While you can purchase peat-free compost (we shouldn’t be buying peat compost anymore for many reasons) at most garden supply centres, why not take control and make your own? It’s easy, cost-effective, and allows you to create your own eco-system.
Below, we've outlined a step-by-step guide to help you get started.
What Is Composting?
Composting is a simple, natural process that involves placing organic materials in a pile or container and allowing them to decompose into nutrient-rich soil for plants.
Getting Started
1. Choosing a Compost Bin
Choosing the right compost bin is a crucial step in successful composting. When selecting a bin, consider how you plan to use the compost and how much you need. Various styles are available, so consider how you want to access and manage the compost.
For small-scale composting, kitchen composters are compact, streamlined, and odor-free. If you're composting on a larger scale, such as for a garden, an outdoor bin may be a better option. You can use a DIY compost bin or purchase one, with materials ranging from wooden pallets and cinder blocks to plastic bins.
When placing one outside, be mindful that it should be easily accessible from the kitchen, somewhere away from a ditch, and where air can freely circulate.
2. What You'll Need
Once you've chosen your compost bin, here are the essential items you'll need to get started:
Shovel or pitchfork for turning the compost
Green materials: Kitchen scraps, coffee grounds, fresh plant trimmings, and grass clippings
Brown materials: Fallen leaves, shredded tree branches, cardboard, newspaper, hay, straw, and wood shavings
Note: Materials to Avoid in Composting
Some materials can create a smelly compost pile and attract rats or other vermin, so it’s important to avoid using them. Here’s a list of items that should not be composted:
Meat and fish
Dairy, fats, and oils
Wood treated with preservatives
Diseased, pest-infested plants, or invasive weeds
Charcoal ash or coal
Dog and cat waste
Certain items, like those treated with pesticides or acidic materials like charcoal ash, can kill the beneficial bacteria in your compost pile, disrupting the decomposition process. Dog and cat waste may contain harmful bacteria or parasites that could make your compost hazardous to use.
Avoid adding plant material that shows signs of disease or fungal spots. These pathogens can survive the composting process and may be reintroduced into your garden when you use the finished compost. Unhealthy plant material should be bagged and disposed of properly.
3. Add Green Material
Green material is high in nitrogen. It includes kitchen scraps such as coffee grounds, peelings, fruit cores, uneaten leftovers, and eggshells. Any kitchen waste that is not greasy or meat can be composted.
Grass clippings, leaves, and weeds are also considered green materials, as is manure from barnyard animals like chickens, sheep, horses, pigs and cattle (but not cats or dogs).
4. Add Brown Material
Brown material is high in carbon. Paper, sawdust, small branches, twigs, and straw all fall into this category. The ideal compost ratio of nitrogen to carbon is 50/50. For every bit of brown material you add, balance it with an equal amount of green material.
5. Add Water
Water is a crucial ingredient for a healthy compost pile. Without enough moisture, your pile will take months to decompose, and it may not break down if it’s too dry. If the pile becomes too wet, it will smell bad and become slimy due to an overgrowth of harmful bacteria. Aim for a damp pile—not dripping wet. If rainfall is insufficient, water your pile weekly to keep things moving.
You’ll know your compost is on track if it becomes hot in the centre. Maintaining this heat is essential for sterilizing the compost and killing weed seeds or harmful bacteria. Heat is a sign that the nitrogen-to-carbon ratio is working correctly. You can pick up a compost thermometer in any good garden centre.
6. Turn the Pile Regularly
To keep your compost pile working efficiently, turn it regularly. Using a shovel or pitchfork, move the outer layers of the pile toward the centre, turning each scoop over. Continue turning the pile until the decomposing material is exposed to the outer edges.
Turn your compost every two to four weeks, depending on your setup. If you’re using a bin with a crank, give it a few turns every week. If your pile is properly heated, moist, and regularly turned, you should have usable compost in about two to three months.
At Fat Tomato, we use a six-bay compost system, where we turn the compost from one bay into the next one.
How to Use Your Compost
Now that you've made your compost, it's time to put it to good use!
Compost is a versatile, multi-purpose resource that can improve the health of many types of plants, from perennials and bulbs to fruit trees, container plants, and lawns. Here are a few ways to incorporate compost into your gardening routine:
1. As a Fertiliser
Compost can be used as a natural fertiliser for new and established plantings. To provide a nutrient boost, simply top-dress your plants by sprinkling compost around the base of your perennials, trees, or other plants.
2. As Mulch
Instead of using traditional mulch, apply a 5 to 10-cm layer of compost to the soil surface. This will help retain moisture in the soil, reduce evaporation, and suppress weed growth.
3. For Potting Soil
Mix equal parts compost, vermiculite, and topsoil to make enriched potting soil. This creates a well-draining, nutrient-rich growing medium for indoor or container plants.
4. Compost Tea
Brew compost tea for a liquid fertiliser that quickly reaches your plants’ roots. This concentrated emulsion provides an easy-to-apply, nutrient-rich solution to nourish your garden.