How to Make Mulch From Leaves and Grass

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Here is how to make mulch from leaves and grass, using the steps that university extension pages describe. Leaves and grass clippings are often free and can cover a bed well, but each one needs a little preparation first. Leaves should be shredded so they do not blow away or mat down, and clippings should be spread in thin layers and allowed to dry. The steps below cover both materials, the depth to aim for, and what to keep out of the mix, including weed seeds and clippings from recently treated lawns.

Quick answer

Shred leaves before you use them. Whole leaves tend to blow away.
Spread fresh grass clippings in thin layers, no more than about a quarter inch thick, and let each layer dry before you add another.
Aim for a leaf layer of about 2 to 3 inches for weed control.
Leave out clippings from weedy lawns and from lawns recently treated with herbicides.

What a mulch layer does for the bed

Mulch has a few jobs, and the sources agree on most of them. The Colorado State mulches guide says, “In general, mulching minimizes evaporation of water from the soil surface, reducing irrigation need by around 50%.” The Clemson guide lists the effects it expects when mulch is applied correctly, including “Mulches prevent loss of water from the soil by evaporation.” It also says, “Mulches prevent crusting of the soil surface, thus improving the absorption and movement of water into the soil.”

Temperature is the other job. The Clemson guide says, “Mulches keep the soil cooler in the summer and warmer in the winter, thus maintaining a more even soil temperature.” The Ask Extension reply puts several jobs together: “Mulch is very beneficial to a vegetable garden – reducing weeds, maintaining soil temperature, increasing water infiltration and reducing runoff, and as it breakdown adds nutrients to the soil.” Those are the jobs to look for when you check the bed after a few weeks.

Start with the right leaves

Leaves are a free source of organic matter, and the Colorado State guide opens by saying, “Leaves are a valuable resource in the landscape.” The useful question is how to use them. The Iowa State guide gives the core advice: “Shred or compost leaves before using them as mulch to prevent matting, reduce their likelihood of blowing away, and speed up decomposition.” Whole leaves are the usual mistake. The Clemson guide explains the trade-off: “Whole leaves have a tendency to blow away, while finely shredded leaves do not allow water to penetrate.”

That trade-off sets the target. The leaves need to be broken up enough to stay put, but not so fine that they seal the soil. The Clemson guide says it is best to shred leaves coarsely, which keeps the layer open enough for rain to soak through while still resisting the wind. Think of the goal as a mat that holds its shape and still lets water pass.

Leaf type can matter as well. The Clemson guide says, “Oak and beech leaves help to acidify the soil for acid-loving plants.” Use oak or beech leaves where that effect is wanted, such as under acid-loving shrubs, and keep them away from plants that prefer a different soil. The source does not give a pH figure, so this guide does not give one either.

Make leaf mulch step by step

Start by gathering the leaves, then shred them. The Iowa State guide’s reasons for shredding are the ones to remember: shredded leaves are less likely to mat, less likely to blow away, and they break down faster. Spread the shredded leaves to a layer of about 2 to 3 inches. The Clemson guide gives that depth for weed control, so the layer is a starting point and not a guarantee of a weed-free bed.

Leaves also belong in compost. The Colorado State guide says that “Tree leaves are high in carbon” and that they “can be added to compost bins in combination with materials high in nitrogen”. In the guide’s terms, leaves are a brown material, and they go in with green materials that are high in nitrogen. If you have no pile yet, starting a compost bin is the first step, and the leaves you would otherwise use as mulch can go there instead.

Make grass mulch the right way

Grass clippings are the fast material. The Colorado State guide says, “Grass clippings make excellent mulch for the vegetable garden.” The Ask Extension reply on the same question agrees, and the method is the same in every source: thin layers that dry between additions. The Colorado State guide puts the rule plainly: “Apply fresh clippings in thin layers (up to 1/4 inch thick) and allow each layer to dry before adding more.” It adds that “The clippings quickly dry down and additional layers can be added weekly.”

Fresh clippings cause most of the trouble. The Ask Extension reply warns that “Wet/green clippings can mat down and cause problems.” The Colorado State guide adds the reason to avoid thick piles: “Do not place fresh clippings in thick piles, as they will mat, reducing water and air infiltration, stink, and may become hydrophobic.” The Iowa State guide gives the same advice in shorter form: “Let lawn clippings dry before applying them to gardens, as fresh clippings may form a dense mat or produce an odor.” The simple rule is to spread thin, let it dry, and then add the next layer.

Clippings also break down quickly. The Iowa State guide says, “Grass clippings decompose quickly, making them ideal for vegetable gardens and annual flower beds.”

Grass clippings and a newspaper base

Grass can also help with weeds. The Colorado State mulches guide says, “A few layers will stop weed seed germination.” It describes a base layer that adds to that effect: “A couple of sheets of newspaper may be used under the clippings to help control weeds.” The same guide warns about overdoing it: “Do not apply newspapers more than a couple of sheets thick or a soil carbon to nitrogen imbalance may occur.” Paper on its own does not stay put, so cover it at once: “The newspapers blow away with a light wind so they must be covered immediately with grass to hold them in place.”

The Colorado State guide also says when the layers can go into the soil: “The grass and newspaper mulch may be cultivated into the soil in the fall, adding small amounts of organic matter.” Use the fall step to turn a season of clippings into soil, rather than leaving the layers to build up over the winter.

What to keep out of the mix

Not every clipping is safe for a bed. The Iowa State guide warns, “Clippings from weed-infested lawns will contain weed seeds.” The Colorado State guide adds a caution about treated lawns: “Do not use clippings from lawns that have been treated with herbicides or other pesticides in the past month.” If you are not sure what a lawn has been treated with, leave its clippings out and use leaves instead.

The Clemson guide makes the same point about the material itself. Mulch helps with weeds only when it is clean: “Mulches reduce the growth of weeds, when the mulch material itself is weed-free and applied deeply enough to prevent weed seed germination or to smother existing weeds.”

How leaves and grass compare with other organic mulches

Leaves and clippings are not the only free choices. The Clemson guide lists organic mulches as “An organic mulch is a mulch made of natural substances such as bark, wood chips, leaves, pine needles, or grass clippings.” It gives layer depths for some of them. For pine needles, the guide says, “A 2- to 3-inch layer of pine needles makes an excellent mulch for acid-loving trees and shrubs.” For pine bark, it says, “A 2- to 3-inch layer of pine bark is good for weed control.”

The Iowa State guide also gives a practical reason to shred wood mulch: “Shredded mulch is less likely to blow or wash away than chips.” That is the same reason shredding helps leaves.

Leaf mold and compost as mulch

Leaf mold is the slow option. The Colorado State mulch guide says, “Compost or Leaf Mold Both make excellent organic mulch for a vegetable garden.” It also notes which compost is best: “Homemade plant-based compost is best but sometimes good local products or bagged products can be found.” Our guide to making a compost pile covers the steps for the pile itself.

The sources we opened do not give a timeline for leaf mold, so the time it takes depends on your own pile and climate.

Depths for leaves, leaf mold and winter cover

The sources give different depths for different leaf products, so keep them apart. For shredded leaves, the Clemson guide says, “A 2- to 3-inch layer of leaves provides good weed control.” For leaf mold, the Colorado State mulch guide says, “Compost or Leaf Mold Both make excellent organic mulch for a vegetable garden.” It then gives a shallower depth: “Apply one to two inches.” Set the two side by side, and the difference is clear: finished leaf mold goes on more thinly than fresh shredded leaves.

Leaves can also serve as winter cover. The Colorado State leaves guide says, “Leaves can be used as mulch to insulate tender or newly planted plants.” Its method is specific: “Place a wire cage around the plant and pile three to six inches of shredded leaves inside the cage, next to the plant.” The cage holds the leaves around the plant, so the layer stays where it is put.

Common mistakes to avoid

Spreading whole leaves. The Clemson guide says whole leaves blow away, so shred them first.
Piling fresh clippings thickly. The Colorado State guide says they mat and reduce water and air getting in.
Using clippings from weedy lawns. The Iowa State guide says they carry weed seeds.
Using clippings from a lawn treated with herbicides in the past month, as the Colorado State guide advises against.

How we chose

We chose extension pages that answer the three questions in this keyword: how to prepare leaves, how to prepare grass clippings, and what to keep out. We kept university extension pages and one Ask Extension reply, and we left out commercial blogs and pages that returned errors. Each quoted sentence was checked against the text of the page it came from.

What we could not verify

The pages we opened do not give a shelf life for leaves or clippings, a ratio of leaves to grass for a bed, or the time a leaf pile takes to become leaf mold. Some leaf pages also cover working leaves into turf, which this guide leaves out.

What the sources do not say

The sources do not say how long shredded leaves take to break down in a given climate, or how much grass a bed of a given size needs. The Ask Extension reply is one expert answer, not a study, so treat it as a starting point rather than a rule. Where a source names a depth, this guide uses that depth and no other.

Frequently asked questions

Can you use grass clippings as mulch?

Yes, according to the Ask Extension reply, provided the layers stay thin and dry between additions. A thick, wet pile is the version to avoid, because it can mat and cause problems.

How thick should a leaf mulch layer be?

The Clemson guide gives a depth of about 2 to 3 inches for leaves, with the aim of weed control. Keep the leaves shredded coarsely, as described above.

Why do leaves blow away from a bed?

Whole leaves are the usual cause, according to the Clemson guide. Shredding them coarsely keeps them in place and still lets water through.

Are weeds a concern with grass clippings?

Weed seeds are the concern, according to the Iowa State guide. Leave out clippings from weedy lawns, and use leaves from your own trees where you can.

Can leaves go into a compost pile instead of onto a bed?

Yes. The Colorado State guide says tree leaves are high in carbon and can be combined with nitrogen-rich green material in a compost bin. The same leaves can serve as mulch or as compost, so choose the use that fits the bed you have.

Sources

https://ask.extension.org/kb/faq.php?id=830764 (opened 2026-10-22)
https://extension.colostate.edu/resource/mulches-for-the-vegetable-garden/ (opened 2026-10-22)
https://hgic.clemson.edu/factsheet/mulch/ (opened 2026-10-22)
https://extension.colostate.edu/resource/using-leaves-in-the-landscape/ (opened 2026-10-22)
https://yardandgarden.extension.iastate.edu/how-to/using-mulch-garden (opened 2026-10-22)