How to make garden compost using tumblers and bins

Home composting is a simple, eco-friendly way to improve the soil quality in your garden. Not only is it the cornerstone to maintaining garden fertility, but it also helps reduce the amount of waste going to landfill. Although councils offer green waste collection, home composting is better for the environment because it avoids the environmental costs associated with heavy transport. But how do you choose the right compost bin for your garden? What recipe creates the perfect compost? Read on to find out the secrets to composting success.

Woman kneeling beside Green Johanna compost bin planting pansies in compost
Green Johanna compost bin

How composting happens

Garden clippings and kitchen peelings contain nutrients that plants can use to grow healthily. However, they need to be well-rotted for plants to absorb them. Composting helps to speed up the rotting process; materials containing carbon and nitrogen are broken down by worms, fungi, insects, and bacteria, all of which need water and air to survive. As they work, bacteria release heat, helping them work even faster.

Guide to choosing a compost bin

You don’t need a container, but it helps to keep the compost neat and to retain heat and moisture; removable sides make it easier to turn the compost and remove it. You can build your own compost bin or choose from a range of specially designed bins; a larger bin will speed up the process of decomposition because the extra mass generates additional heat. Key things to consider when choosing a compost bin are:

  • How much kitchen and garden waste you are likely to have.
  • How much space you have.
  • Your maximum budget.

Wooden compost bins

Traditional, square-shaped wooden compost bins have no lids, making it easier to turn the compost; slatted sides allow air to circulate through it. However, you need to cover the top of the heap with a piece of tarpaulin or old carpet to keep the rain out. It is also necessary to leave the entire pile before use. It helps to have two wooden compost bins if space allows: one ready to use, another to add new material.

Plastic compost bins

Most plastic compost bins are cylindrical with a lid. A key benefit is that you can keep adding new material to the top, whilst removing ready-made compost from the bottom. However, they tend to be smaller than wooden compost bins and can therefore be slower (the exception being hot compost bins such as the Green Johanna and Hotbin, which benefit from superior insulation, allowing them to keep more heat in and speed up the process of decomposition). They can also be difficult to turn compared with wooden compost bins.

Tumbling compost bins

Tumbling composters such as the Maze compost tumbler have a rotating cylinder on a frame that can be turned to mix the compost and aerate it. This helps to speed up the process of decomposition. However, once the cylinder is full and decomposition starts, you won’t be able to add to it. Tumbling compost bins are relatively small-scale, making them a good choice where space is limited.

Siting your compost bin

It is important to consider both aesthetics and function when choosing where to place your compost bin. It needs to be convenient enough to add and remove material, without detracting from the beauty of your garden. Choose a level, well-drained area, close to the garden hose if possible to keep the pile moist. Placing on soil or grass will allow worms and insects to get in, speeding up the process of decomposition further.

The micro-organisms responsible for decomposition work best in constant conditions, so it is better to avoid extremes of temperature and moisture if possible; a partially shaded site is best. A poorly drained site will slow decomposition because bacteria, microbes, and insects responsible for aerobic digestion will not be able to get enough air. This can sometimes lead to a bad smell, so it is best not to place the bin next to where you sit in the garden.

How to make compost

After choosing a compost bin and positioning it, it is time to start adding material. Ideally, start this in the spring as the weather warms; higher temperatures will speed up the decomposition process.

The main rule when composting is not to let any single material dominate. You are looking for roughly equal quantities of brown, carbon-rich matter (e.g., dry leaves, cardboard) and soft, green, nitrogen-rich material (e.g., grass clippings). Too much carbon and the compost will take a long time to decompose; too much nitrogen and your heap risks becoming a bad-smelling sludge.

Green composting materials

  • Grass cuttings (free from weedkiller)
  • Soft prunings
  • Annuals, weeds before they set seed
  • Fruit and vegetable scraps (uncooked)
  • Tea bags, coffee grounds
  • Manure
  • Seaweed, kelp

Brown composting materials

  • Cardboard (torn up)
  • Shredded newspaper (not shiny paper)
  • Paper bags, scrunched paper
  • Stray, hay
  • Wood ash (not coal)
  • Dry leaves
  • Vacuum cleaner contents

Start with a 10cm layer of coarse woody material to help with air circulation at the bottom of the heap. Build up in 15cm layers, alternating between green and brown materials to reduce the need to turn the compost later. Cut everything into small pieces to increase the surface area for microbes to work on. Sprinkle garden soil on top of each layer to introduce bacteria and fungi.

When the compost bin is full, the materials will start to heat up as decomposition starts. The ideal temperature is between 50 and 70 degrees Celsius (you can use a compost thermometer to check). Turn the compost once a month with a garden fork to increase the amount of oxygen available for aerobic digestion and to move materials from the outside to the centre of the heap; more often than this and the temperature won’t have a chance to build up. Add water to the material if dry, but don’t saturate it.

After as little as three months, you should have a dark brown, rich and crumbly compost with a sweet, damp woodland smell. Use as a soil improver throughout the garden.