How to Make Compost - The Beginners Guide

Compost is one of the easiest things you can make at home provided you follow the key requirements for what makes great compost. Home composting allows you to turn waste material into a beautiful rich resource to help your garden thrive. There is no garden without compost, and making your own is one of the best things you can do to cut your carbon footprint.

Right bin size

The sides of the bin should be at least 1m (3ft) in length and height. This ensures the volume of material in the bin is sufficient for a core to form, which will generate and retain heat to speed up the composting process. Smaller bins don't allow enough heat to build up so they take an age to make compost. A bin that measures at least 1m x 1m (3 x 3ft) may seem large, especially if you have a small space, but you can always grow plants up the side and make a pallet lid so containers can sit on the top.

Image: Wooden slatted compost bins with squash growing in them

A bin of that size will produce enough compost to mulch approximately four or five 1.2m x 3m (4ft x 10ft) raised beds. The bin should also have good airflow to avoid anaerobic decomposition, which slows down the process and can make the contents pretty smelly. A bin made from wooden slats or pallets is ideal.

The right ingredients 

When composting, there are two categories of ingredients - green and brown. Green materials are high in nitrogen and often in moisture content - properties which facilitate decomposition - while brown materials are high in carbon and have low moisture content. Striking the right balance of both types of material creates high-quality compost.

Image: A mix of various different green and brown compost ingredients

Before we go cover some examples of green and brown materials you need to know what kind of ratio of material to add to your compost bin. I find that a 50:50 ratio of greens and browns is the easiest to follow. A simple example of this is to place a bucket of green material for each bucket of brown. Compost does not need to be any more complex than that.

Green materials

1) Used coffee grounds and plastic-free tea bags

2) Weeds without seedheads

3) Fruit and vegetable scraps

4) Lawn clippings

5) Horse and cow manure

6) Freshly-cut plant material

7) Comfrey and nettles

8) Seaweed

9) Spent brewery grain (from a local brewery)

10) Hair clippings (from barbers/hairdressers)

11) Wool

Brown materials

1) Dust from vacuuming

2) Chippings and sawdust (from untreated wood)

3) Autumn leaves

4) Hay and straw

5) Autumn and winter woody prunings

6) Fallen pine needles

7) Wood ash

8) Tissues and paper towels

9) Spent compost (from this-season's containers)

10) Cardboard and newspaper

Image: Cardboard is a wonderful brown compost ingredient. To make it easier to tare up (or remove any plastic tape) leave it out in the rain and then tare and strip when wet. This will make the job much easier!

The greater the variety of green and brown materials, the more balanced your compost will be.

Tip: Some ingredients are both green and brown, such as used chicken or rabbit bedding: the manure is the green element and the bedding is the brown.

Keep material varied

The key to lazy composting is to add as many different ingredients (green and brown) as possible. Incorporating just a few materials means there is a risk the compost won't be balanced, both in terms of nutrients and pH (acidity or alkalinity). Aim to have a rough balance between green and brown material in terms of volume, and always include a good variety of both. For example, if you have a lot of green plant material to compost, keep the bin contents diverse by adding other green ingredients such as manure or coffee grounds plus a similar quantity of brown material at the same time.

Full compost bin

Compost bins can be deceptive - they accommodate a much larger volume of material than you might think. Even when they look completely full, there is usually room to add more. Once the material has reached the top of the bin and is threatening to overflow, it's time to compress the contents so you can add more to the pile. One option is to place cardboard over the top of the compost, weight it with bricks or stones then wait a few days for the contents to settle.

My preferred method is much easier - I simply walk over the top of the heap a few times to compact everything down. Ensuring your bin is filled to maximum capacity means you won't be left disappointed when the compost is ready and you find the pile has shrunk to a third of its original size!

Once the compost bin is completely full I like to place a covering over the top. This not only helps shed excess rainwater but also reminds me not to add anything else to it.

When is compost ready?

This lazy method will provide you with ready compost in around six months, depending on the season as well as the materials used. Some people like to turn the pile every couple of months and this can help the decomposition process, but it isn't really necessary and I tend to just leave the pile alone. Compost is ready when it has a lovely, fresh earthy smell - like a vibrant forest floor - and the texture is coarse but crumbly. Some twigs and leaves that have not fully broken down may still be visible but this doesn't affect the quality and is nothing to worry about.

Image: Homemade compost around 2 months from completion

Tip: Roughly chopping up materials for your compost bin will reduce decomposition times by at least a month or two.

Wildlife in the bin

Rats

People are often discouraged from starting composting because they fear a bin might bring rats into the garden. Rats usually visit bins where cooked food, dairy and/or meat are present but these ingredients should not be composted and are not included in the list of green or brown materials. If there is nothing in there for a rat to eat, your compost bin is unlikely to become a rat magnet. Rats may well seek out a warm compost bin in a cold winter, but wouldn't you prefer to have one in your bin rather than it attempting to get into your house?

Rats are going to be around whether you have a compost bin or not, but if you're still concerned then site your compost area at the far end of your garden, or consider investing in a rat-proof compost bin. 

Beneficial wildlife

Not all creatures that you find in the compost bin are unwelcome in the garden. Slow worms and toads may also seek shelter in the warmth. If you come across one, move it carefully (especially during hibernation) to a safe space - it will return the favour by reducing numbers of troublesome garden pests, particularly slugs.

Note: The information above is an extract from my book The Vegetable Grower's Handbook which is the perfect gardening book for anyone wanting to get the most from their space.

The world's easiest compost recipe

If you have collected a load of autumn leaves, and you have a lawn that perhaps needs the final cut of the season, then you are in luck! Autumn leaves can take a bit of time to breakdown, however if you sprinkle them over the lawn and run a mower over them, you get an instant 50:50 mix of green and brown material, and the chopping of the lawnmower will allow the leaves to decompose much faster. You can fill a whole compost bin using this method if you have a big enough lawn, and it is a great use for stored leaves over winter when the lawn starts growing again in spring.