Yard waste: grass clippings, prunings, shredded material… compost it instead of burning it

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Spring grass clippings, hedge trimmings, fall leaves: in a house with a yard, yard waste often adds up to far more volume than the peels from the kitchen. Managed well, it becomes a valuable resource for your compost and your soil. Managed poorly, it clogs up the compost bin, makes it rot, or goes up in smoke at the back of the yard.

Here's how to compost it properly, how to cut down the volume by mulching, and why you should never burn it.

The yard produces more than the kitchen

In France, each person is estimated to produce an average of around 350 lb (160 kg) of yard waste a year. That's more than double the roughly 155 lb (70 kg) of compostable waste, mostly from the kitchen, that each person produces a year. And this waste comes in waves: huge amounts of grass clippings in spring, prunings in late winter and summer, and mountains of leaves in the fall.

A single compost bin can't absorb it all at once. That's why it pays to combine three solutions: compost some of it, keep a supply of dry material for later, and leave the rest in the yard as mulch.

Grass clippings: never on their own, and in thin layers

Freshly cut grass is a green material very rich in nitrogen and water. It breaks down very quickly… too quickly. Dumped into the compost bin in a thick layer, it packs down, pushes out the air, and turns into a slimy, smelly mass: a classic trap.

• Always mix grass clippings with dry material: dead leaves, shredded material, torn cardboard.
• Add them in thin layers, mixing them in each time with the material already there.
• If you're short on browns, let the extra dry for a few days in a pile next to the compost bin before adding it. Dried grass then behaves more like a brown material.
• Don't use clippings from a lawn treated with weed killer: they don't belong in compost.

Key takeaways

Grass clippings on their own rot; mixed grass clippings compost. Every time you empty the mower's grass catcher into the compost bin, add some dry material too.

Prunings and branches: shred them first

Branches, rose canes, and hedge trimmings are brown materials very rich in carbon. Left whole, they take years to break down and create gaps in the compost bin. So it's best to cut or shred them before composting.

• For small quantities: hand pruners or shears will do. Cut into pieces a few inches long.
• For large volumes: a chipper shredder is worth it. Some local governments lend them out or organize chipping days: check with your city or county.
• Running the lawn mower over a pile of small, thin prunings or leaves also chops them up.

Shredded material, the ideal supply of browns

Once shredded, your prunings become shredded material: a mix of small wood chips and leaves. It's the ideal dry material to balance food scraps and grass clippings, because it gives the compost structure and lets air circulate.

A good habit: store your shredded material next to the compost bin, in a container, a bag, or a sheltered corner, and grab a handful every time you add something wet. It also makes the ideal bottom layer for starting a compost bin: we explain how in our guide Starting your compost bin step by step. Shredded material also makes an excellent mulch for flower beds and around the base of shrubs.

Willy's tip

Keep some well-dried shredded hedge trimmings in an old trash can with a lid near the compost bin. In summer, when grass clippings and fruit peels pour in and dead leaves are just a memory, it will save you from having too many greens.

Mulching: the solution that means composting less

The best yard waste is the waste you never collect. So prevention comes first: before composting, ask yourself what can stay in the yard.

• Mowing without bagging (or "mulch mowing"): the mower cuts the grass very finely and leaves it on the lawn, where it breaks down quickly and feeds the grass. Nothing left to collect.
• Mulching with grass clippings: a thin layer of about 2 in (5 cm) around vegetables or shrubs. Any thicker and the grass ferments.
• Mulching with shredded material or dead leaves: it keeps moisture in the soil, keeps weeds down, and feeds soil life as it breaks down.

Mulched soil rich in organic matter also attracts earthworms, which then pull this material down into the ground themselves: see our guide Reintroducing earthworms into your garden and the one on the ecological role of earthworms.

Burning yard waste: often restricted, and polluting

Even so, some gardeners still burn their yard waste at the back of the yard: in France, an estimated 15% of households with a yard do so. Yet it's banned there all year round, and in many other places it's restricted or discouraged.

What the rules say

Rules on open burning of yard waste vary from country to country, and sometimes from one area to another. Depending on where you live, burning may be banned outright, allowed only under certain conditions, or subject to rules on smoke and nuisance to neighbors. Backyard burn barrels and garden incinerators may also be covered by these rules.

Breaking these rules can lead to a fine or other penalties. Exceptions may exist, for example to deal with a plant disease or an invasive plant, but they are usually limited. Check with your city, county, or local waste service before doing anything.

Why it pollutes

Plant material burns poorly, especially when damp, and gives off large amounts of fine particles that are harmful to the lungs. According to air quality measurements taken in France, burning 110 lb (50 kg) of plant material emits as many particles as a recent diesel car driven around 8,100 miles (13,000 km) in the city. Not to mention the nuisance for neighbors and the risk of fire.

Did you know?

Burning your yard waste also wastes a resource: the branches you burn are exactly the brown material so many compost bins are short on, and dead leaves make free mulch and excellent leaf mold.

Whatever you can't compost, shred, or use as mulch can be taken to your local drop-off site or put out for your town's yard waste collection, if there is one. To learn more about separate collection of organic waste, see our guide Compulsory biowaste sorting since 2024.

To handle large volumes of yard waste, a large-capacity bin such as the Compostys wooden compost bin is better suited than a small kitchen composter. And to mix grass clippings and shredded material without turning the whole pile, the Brass'Compost compost aerator saves a lot of time.

In summary

Yard waste adds up, around 350 lb (160 kg) per person per year in France, but it's a resource. Grass clippings are composted in thin layers, always mixed with browns; branches are shredded first, and the shredded material becomes your supply of dry material. Mowing without bagging and mulching mean there's far less to collect. As for burning, it's often restricted or banned depending on where you live, can lead to a fine, and is highly polluting.

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