Composting grass clippings: how-to guide

Grass clippings can be a great addition to your compost bin. Discover how to compost grass clippings effectively and how to use them once composted.

Even an average-sized lawn can produce a lot of grass clippings during the year. With the grass growth only stopping or slowing due to low temperatures or drought, you may be cutting the grass for around 8 to 10 months of the year. We will show you how to recycle your grass clippings into the best garden compost to help you avoid all those trips to the tip.

Can you compost grass cuttings?

As a source of nitrogen-rich green waste, grass clippings can make an excellent garden compost at home. However, fresh grass clippings contain a large amount of water and can take up a lot of room in your compost bin. Thankfully, it does not take long for them to begin rotting down and decreasing in volume. However, due to their high moisture levels, grass clippings can quickly become soggy when left to rot on their own.

Organic material collected from the garden is generally high in either nitrogen or carbon. Green waste, which includes grass clippings, tends to be nitrogen-rich. Whereas brown waste, or woody material, is higher in carbon. For a home composting system to work efficiently and not become overly wet or dry, you ideally want to aim for a ratio of one-third green waste to two-thirds brown waste.

If you do not have enough of either waste type, you can simply leave it to one side until you have enough to add to your compost bin or heap.

Do lawn clippings make good compost?

Being low in carbon and high in nitrogen, grass clippings are quickly broken down by bacteria and microorganisms. However, as previously mentioned, to fully decompose in a compost heap, the right carbon-nitrogen ratio is important to ensure that both parts break down thoroughly. Once decomposed, garden compost generally contains 0.5 to 1.5% of nitrogen, phosphorus and potassium. However, it also contains beneficial microorganisms that when added, help maintain soil health. Along with feeding the soil, adding garden compost to the soil can also improve the soil structure and texture.

How to compost grass clippings

When composting lawn clippings, the same ratio for general composting applies. Here is a step-by-step guide to making compost using grass clippings:

• When adding to an existing bin or heap, spread the fresh grass clippings in an even layer on the compost.
• If starting with an empty bin, put a first layer of chopped-up twigs and branches under any grass clippings to aid airflow and drainage.
• Where possible, add the grass clippings or other green waste and brown material in alternate layers.
• Turn the compost over every 2 to 3 months to incorporate air into the compost and prevent it from becoming compacted.
• If the compost becomes too wet, add some shredded cardboard or twigs and turn it over to balance the moisture levels.
• If the compost is too dry, add some water or more lawn clippings to provide more moisture.

Under optimum conditions and a composting temperature of 40 to 60 °C, your grass clippings can turn into usable compost in as little as 6 months.

How to use composted grass clippings

When the compost has turned almost black and crumbles between your fingers, it has decomposed and is ready to use. In this form, the composted grass clippings are ideal for mulching beds and borders and for improving the soil. To apply as a mulch, simply spread a layer around 5 to 7cm thick on the soil, leaving some space around any plants. You can then either gently fork in the compost or leave it for the worms to mix into the existing soil. You can also mix your composted lawn cuttings with some garden soil and grit for drainage to make a potting compost mix for containers.

If you want to start composting your lawn clippings, you can buy a compost bin at most garden centres or often via your council. However, you can also make your own compost bin using some simple materials.