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Can You Compost Leaves? Yes — They Are the Best Brown You Have

Leaves are the ideal carbon layer in a heap, and composted alone they make leaf mould. Shred them, or they mat into sheets that shed water.

By Zakaria 2 min read Save to Pinterest — opens Pinterest in a new tab
Someone raking fallen autumn leaves into a pile on a lawn
Photo: Greenstock, Pixabay Content License, via Pixabay
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Yes — they are the best brown material most gardens produce. Free, in quantity, exactly when a heap needs carbon. Shred them first, or whole leaves mat into wet sheets that shed water and stall the heap.

Two different things to make

This table answers the question on its own
In a mixed heapAs leaf mould
WithGreen waste, turnedLeaves alone, left alone
Driven byBacteria, heatFungi, cool and damp
TimeA season or two1–2 years; 3 for oak and beech
ResultCompost — feedsConditioner — holds water, opens soil
EffortTurning, balancingAlmost none

Making leaf mould

Genuinely effortless:

  1. A wire cage, or a bin bag with holes punched in it.
  2. Fill with damp leaves. Wet them if they are dry.
  3. Leave it alone. No turning, no balancing, no attention.
  4. Shredded leaves roughly halve the time.

It is low in nutrients compared with compost — it conditions rather than feeds — and it is the traditional base for seed and potting mixes.

Shredding is the one thing worth doing

Whole leaves lie flat and mat into layers water runs off rather than through, which stalls decomposition and makes a heap unpleasant to turn. Run a mower over a spread of leaves on the lawn — collection box on or off — and it is done in minutes. A leaf shredder or a strimmer in a bin does the same.

Which leaves to keep out

  • Walnut — contains juglone, which inhibits many plants and persists. Compost separately and age well, or leave out.
  • Diseased leaves — rose black spot, apple scab. Only safe in a heap that reliably gets hot; a cool heap will not kill the spores.
  • Conifer needles and evergreens — acidic and very slow. Sparingly, or composted separately for ericaceous plants.

On the lawn

A thick layer left in place kills grass

It blocks light and traps moisture against the sward, causing yellowing, encouraging disease and killing patches outright over a wet winter. Rake thick drifts off and compost them.

A light scatter is different — mow over it and the chopped leaves drop into the sward, feed the soil and disappear. That is free soil improvement, and it saves raking.

Common questions

Can you compost leaves?

Yes, and they are the single most useful brown material most gardens produce. A compost heap needs a high-carbon component to balance nitrogen-rich green waste, and autumn leaves arrive free and in quantity at exactly the right time. The one thing to get right is shredding them, because whole leaves mat together into wet sheets that shed water and exclude air, which stalls a heap rather than feeding it.

How long do leaves take to compost?

In a mixed heap with plenty of green material and regular turning, a season or two. Composted alone as leaf mould they take considerably longer — one to two years for most deciduous leaves and up to three for tough ones like oak, beech and sweet chestnut. The difference is that leaf mould is made by fungi working slowly in cool damp conditions rather than by the bacterial heat of an active compost heap, and that slowness is inherent to the process.

What is leaf mould and is it worth making?

Leaf mould is what you get when leaves break down on their own, and it is a superb soil conditioner — dark, crumbly and excellent at holding moisture and improving structure. It is low in nutrients compared with compost, so it conditions rather than feeds, and it is the traditional base for seed and potting mixes. It is also almost effortless: a wire cage or a bin bag with holes punched in it, filled with damp leaves and left alone, does the whole job.

Which leaves should not be composted?

Walnut leaves contain juglone, which inhibits the growth of many plants and persists for a time, so compost them separately and age them well or leave them out. Avoid any leaves showing signs of disease such as rose black spot or apple scab unless the heap reliably gets hot, since a cool heap will not kill the spores. Evergreen and conifer needles are acidic and very slow, so add them sparingly or compost them separately for ericaceous plants.

Do I need to shred leaves first?

It is the single biggest improvement you can make. Whole leaves lie flat and mat into layers that water runs off rather than through, which both stalls decomposition and makes a heap unpleasant to turn. Running a mower over a spread of leaves on the lawn, with or without a collection box, shreds them in minutes and roughly halves the time they take to break down. A leaf shredder or a strimmer in a bin does the same job.

Can you just leave the leaves on the lawn?

A light scatter, yes — mowing over them chops them into the sward where they feed the soil and disappear. A thick layer left in place is a problem, because it blocks light and traps moisture against the grass, which causes yellowing, encourages disease and can kill patches outright over a wet winter. Rake thick drifts off the lawn and compost them; mulch-mow the thin covering that remains.

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