What Is Mulch and What Is It Used For?

By Lisa A. Koosis

March 05, 2026

Mulch is the unsung hero in any garden. Adding these protective, aesthetically pleasing materials around plants, trees and shrubs can improve your garden's beauty and its health.

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What Is Mulch?

Mulch refers to any material that covers and protects soil. Essentially, mulch recreates the conditions of a forest floor as leaves and twigs fall from trees and decompose.

Depending on the mulch you use, it can beautify a garden, conserve water and improve soil structure to foster plant growth. Mulch can also define garden spaces, indicating walkways or off-limits areas.

What Are the Different Types of Mulch — and What Are They Used for?

Mulch falls into two main categories: inorganic and organic materials.

Inorganic Mulches

Besides providing a decorative accent to gardens, inorganic mulches, such as pea gravel, marble chips and river rocks, improve drainage and control weeds. In coastal areas, mulch made from crushed clam, oyster or scallop shells also repels soft-bodied garden pests, such as slugs and snails.

Landscapers often pair these inorganic mulches with landscaping fabric or plastic sheeting to control erosion, insulate plant roots and create an additional barrier against weeds.

Organic Mulches

Organic mulches can also improve a garden’s aesthetics, conserve water and control weeds. However, organic mulches are plant-based, so as they break down, they provide the soil with nutrients that enrich growing plants.

Many types of organic mulches also offer additional benefits, such as:

Erosion protection: When used on hills and slopes, wood chip mulch and shredded bark safeguard against soil loss due to water runoff.
Cold-weather insulation: Think twice before you rake up fallen autumn leaves. They provide a protective layer that insulates plant roots throughout the winter freeze.
Microbial activity enhancement: Organic mulches create an ideal environment for microbes, which are essential for healthy plants. They contribute to healthy soil and promote plant vitality.

What Is Mulch Made Out of?

Inorganic mulches typically consist of synthetic materials, such as plastic or rubber from recycled tires. They may also be made from gravel, small stones or crushed seashells.

Organic mulches are more varied and may be made out of:

Sawdust
Corn cobs
Hay/straw
Tree bark
Pine needles
Cardboard sheets
Grass clippings
Shredded leaves
Hazelnut or cocoa bean shells
Newspaper that uses soy-based inks

Some gardeners also view ground-covering plants, such as pachysandra or creeping thyme, as living mulch. These hearty plants spread quickly, keeping moisture in and weeds out.

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When, Where and How Should I Use Mulch?

How, when and where you use mulch depends on your specific needs and the type of mulch you choose.

Where to Mulch

Landscapers typically use mulch around plants, trees and shrubs. However, you can use mulching material anywhere you want to protect the soil and beautify your garden. That may include in and around:

Freestanding planters
Raised garden beds
Bird baths or statuary
Walkways and borders
Children's play areas
Vegetable gardens
Young plants
Slopes and other areas prone to erosion

When to Mulch

You can mulch at any time of the year. However, to maximize the benefits, opt for spring or late fall. Then, in summer and winter months, touch up spots that have washed or blown away.

Spring Mulching

Spring mulching refreshes the look of flowerbeds and suppresses weed growth. Wait for late spring, after your bulbs have sprouted and nearby trees have shed any litter, such as helicopter seeds. Lock in moisture by spreading materials after a light rain.

Fall Mulching

Autumn mulching helps winterize your garden, insulating roots from cold and dryness. Opt for lightweight organic material, such as pine needles or straw.

Summer and Winter Mulching Refreshes

During summer or winter months, refresh your mulch to provide additional protection during temperature extremes, particularly if rain or wind has caused loss of material.

How to Mulch

Before you lay down mulch, remove any weeds and rake the soil until it's level. Then, spread an even layer of material.

If you’re using a fine mulch, such as sawdust, lay it about 1 to 2 inches deep. For coarser materials, such as pea gravel or wood chips, increase the depth to 3 to 4 inches. Regardless of depth, never pile mulch against tree trunks or plant stems because it can cause rot.

How Can I Choose the Right Mulch?

When selecting mulch, consider: your garden's needs, your desired aesthetic and how much you're willing to spend. The time of year you're mulching also matters.

Garden Needs

Each garden has unique needs, so choose mulch that'll get the job done. Erosion-prone areas, such as slopes, may benefit from natural materials that are less prone to movement, such as shredded bark. If your soil needs a boost, choose a rich organic mulch that provides nutrients as it decomposes. Planning a playground? Choose rubber mulch for its superior shock absorption.

Aesthetics

Mulch comes in various textures and colors. Brown, reddish-brown and other earthy colors can give your garden a natural look whereas black mulch creates drama. If you want a more creative or whimsical look, such as for a children's play area or a butterfly garden, consider DIY mulch dyes for a custom color.

The size and texture matters, too. For example, choose smooth river rock for the zen feel of a meditation garden or pick classic pea gravel to give pathways a clean, crisp look.

Cost

According to Lawn Love, a bag of mulch costs anywhere from $2 to $13 (CAD 2.73 to CAD 18) per bag, with each bag covering about 10 square feet if you spread it to a depth of 2 inches, so set a budget before selecting material. Costs vary by material, quality and even color. For example, plain straw or pine bark typically sit at the low end of the price spectrum, while specialty materials imported stone, can add up quickly. Your region may also impact costs, particularly if you live in a remote area where materials aren't readily available.

Season

For autumn or winter mulching, choose lightweight organic materials that will protect your plant's roots and decompose when the weather warms, providing nutrients to the soil. If you're mulching in spring, weed suppression and water conservation become more important.

Benefits of Mulch

Mulch gives your landscaped areas a clean, consistent look. Along with projects like installing sod and adding decorative plants, mulch can help improve your home's curb appeal. But it benefits your plants in other ways as well, like:

Retains moisture to reduce your watering needs
Adds nutrients to the soil for plants when using organic mulch
Insulates soil to keep it warm in cooler weather and cooler in the summer
Makes it more difficult for weeds to grow
Protects against erosion
Helps repel some insects

Mulching more of your lawn cuts down on how much grass area you have to mow and can reduce lawn care service costs since there's less grass to maintain.

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