How to compost: recycle waste and improve your garden

Why should I make and use compost in my garden?

Making your own compost will save money as it reduces the amount of fertiliser you need. It is the ultimate form of low-energy recycling: the faded blooms and cuttings from your garden are broken down and fed back to the soil, supplying it with precious nutrients. A single handful of compost contains around ten billion organisms, and using it in your garden guarantees improved soil structure and well-nourished earth. This leads to plants that will grow faster and be more resistant to pests.

From waste to nutrient-rich soil

Composting transforms organic waste into valuable nutrient-rich soil perfect for planting.  As plant matter decays, an organic material forms that effectively retains water and nutrients, supporting better long-term growth.  Soil rich in this decomposed organic matter also contributes to a more crumbly overall soil texture that plants love. A healthy compost heap provides the right conditions for this transformation process to work.

What is a composter?

A composter is a wooden or plastic container used to produce compost. “Quick” or “hot” compost bins are special thermally insulated containers, usually made from plastic, which efficiently maintain a higher temperature to accelerate the decomposition process. Compost bins usually have one or multiple extraction flaps so that you can access the compost easily when it’s ready to use. They are available in different sizes and for different budgets.

What types of compost bin are available?

How to make and maintain compost

Making good-quality compost doesn’t require fancy equipment. All you need is a bit of space in your garden, a shop-bought or homemade compost bin, and knowledge of proper composting techniques.

Compost bin site

Position your compost bin so that it’s easy to get a wheelbarrow to it, and the bin in direct contact with the soil, not on tiles or stone – it’s important that the substrate is water-permeable. The area should ideally be shaded and sheltered from wind; under a tree or shady bush is ideal.

Container material

We recommend using wood or plastic for your compost container. These materials are durable and can withstand external influences for a long time. The composting process requires air, so you should choose – or build – a container with one side open. If you have a large garden, we recommend setting up two or three compost bins for an efficient system: you can add organic waste to one bin while the compost in another is in its rest phase. Small composters are available, so there’s nothing to stop you from making compost on a terrace or balcony.

Materials and tools required for composting

• Mature compost or soil
• Quick-composting bin or compost container
• Wheelbarrow
• Shovel and spade
• Pitchfork

How to use your compost

Sieving

Before using compost in your garden, you need to make sure it's fine enough. Set up a garden riddle or soil sieve at an angle and shovel compost through it. This will remove any little sticks and stones and other impurities, leaving only ready-to-use compost.

Applying

After six to twelve months, the fresh compost will be suitable for use as an organic fertiliser. The nutrient content of your compost is not easy to determine, as it depends on what you put in the composting pile. With that in mind, shrubs and less demanding plants may be fertilised exclusively with compost, but elsewhere we recommend reducing the fertiliser application rate by 50% or so, depending on how hungry the plant is.

Application rate

Apply around 3 to 4L per square metre – that’s around a spadeful. If you’re using your compost as a soil conditioner, it must have first matured for a year or more; this means it is further broken down and will contain fewer nutrients, but will also be much richer in a stable form of decomposed organic matter that permanently improves the condition of your soil.

How to keep your composter working well

Creating and maintaining a composter is simple enough, and with a little extra advice, you can maximise the results.

Use the right composting mix

Always mix coarser waste, such as shrub cuttings, with moist vegetable scraps and dry, nutrient-rich waste such as wood cuttings or foliage. Don’t use large quantities of the same material in one go, as this can stop the mixture from decomposing evenly. 

Consider the composition of your waste

In addition to air and water, the compost-making microorganisms in your bin or heap also need organic carbon (C) and nitrogen (N). For best results, you should aim to maintain a carbon to nitrogen ratio between 25:1 and 30:1.

Moist green kitchen waste and young plant cuttings are full of nitrogen, whereas dry matter – such as twigs, wood cuttings, autumn leaves or straw – is rich in carbon. Grass cuttings decompose quickly, so you should add them to your compost pile in small quantities and add a handful of bonemeal to support the decomposition process. Dry twigs and branches are also known as “brown waste”, and the smaller they are shredded before adding to your compost bin, the more quickly they will decompose.

What can go into my composter?

You can compost organic, biodegradable matter, such as garden waste or kitchen vegetable scraps. The more varied the waste, the richer your compost will be.

What you can compost

• Bedding from small pets
• Eggshells
• Coffee grounds, tea bags, filters
• Newspaper, kitchen roll
• Pot plants, cut flowers
• Fruit and lawn cuttings in small quantities only
• Weeds, but only without seeds

Shredding plant cuttings and garden waste

Twigs and branches from hedges and shrubs are suitable for composting, along with other plant waste, but you should shred them first. This increases the surface area for microbes which means the garden waste will decompose more quickly. We recommend using a garden shredder to make the job easy; these use blades to chop your garden waste effortlessly.

Compostables at a glance

Use the right ratio of matter to keep your compost pile healthy. Putting in compostable matter in the right proportions will ensure your composter contains the right mixture of oxygen, nitrogen and moisture to effectively create a compost rich in nutrients.

Composting autumn leaves

If you want to add fallen autumn leaves to your compost, you can collect them using your lawn mower. It’s best to mix the leaves with fresh grass cuttings, as the dry leaves help to ventilate the grass cuttings and prevent rotting. The leaves add a carbon-rich component to the nitrogen-heavy green plant waste – a mix that is key to successful composting.

If you have a large garden, you shouldn’t add the leaves to your compost bin all at once and can instead create a simple leaf store. Just use posts and wire mesh to create an aerated bin for your collected leaves. You can add these to your compost gradually throughout the year.

Compost problems

Your composting may not go perfectly at first. A few potential problems may crop up, but they are usually simple to solve.

Smelly compost

A rotten-smelling compost pile is often caused by waterlogging, most likely from adding too many wet ingredients. Unfortunately, you have to start again from scratch, as there’s no rescuing rotten compost. Make sure you use the right ratio of waste and layer it properly.

Mouldy compost

Mould spores are present in all garden soils and are completely natural. However, if you notice serious mould, you may have added too much damp matter to your compost bin. Try to rearrange your compost and thoroughly mix the dry matter with damper material; the mould should then start to subside.

Compost is not ready

Mature compost needs time. Depending on the season and temperature, it may take six to twelve months before your various ingredients break down into usable nutrient-rich soil. Compost does need rest time, but you also need to turn it or dig it up occasionally. If the volume of your compost pile has reduced by around a third, then you know it is time to get out your shovel. Turning the heap ventilates your compost and accelerates the process.

Summary: how to compost

• Compost made from garden and kitchen waste is a nutrient-rich natural fertiliser for your plants.
• Quick compost bins make compost faster and more compact, but they're more expensive than wooden compost bins or open compost heaps.
• Start your compost pile with layers: the bottom layer should be coarse shredded matter followed by garden soil or compost.
• Cover the compost and leave it to mature for nearly a year.
• Make sure you use the right ratio of carbon-rich brown and nitrogen-rich green matter (25:1).
• Add to the compost pile regularly.
• Food remnants of animal origin, baked goods, grease, oil and inorganic matter are not suitable for composting.
• If your compost starts rotting, you need to start again. Mouldy compost benefits from having dry matter added.