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How to Choose the Right Mulch

By selecting a mulch that suits your plants and site conditions, you can achieve healthier soil, happier plants, and reduced erosion.

Pine Needle Mulch iStock

What’s the secret to preventing weeds from sprouting? A 2-inch-deep topdressing applied once the ground thaws will do the trick. When it comes to mulch, there are many options to choose from. Read on to learn about the types of mulch and the benefits of each.

Wood Chips

You can’t beat the price of wood chips, which many tree companies and townships give away for free. Chips break down slowly and are best used around shrubs and trees to protect their roots. For more a more decorative mulch, reddish-brown pine bark nuggets will give your garden a neat, natural look. These nuggets can be as large as 3 inches long and work best in flat beds, where they won’t float away during a heavy rain.

Gravel

Stone absorbs more heat than organic material, making gravel a death sentence for some plants and a haven for others. Reserve this option for succulent-filled or cold-climate gardens.

Compost

Hardwood Mulch iStock

This “black gold” doesn’t prevent weeds as well as woody mulches do, but it’s excellent for building up nutrients and repairing soil. Spread a generous layer over your flower beds and vegetable patch.

Hardwood

Made of shredded bark from hardwood trees such as maples and oaks, this sturdy mulch compacts over time so it resists blowing or washing away. Because of its staying power, hardwood mulch is ideal for sloped beds and gardens in wet climates. Carbon-rich bark is a good choice around shrubs and trees but less so for perennials.

Pine Needles

Also known as pine straw, long-leaf pine needles work best around acid-loving trees, shrubs, and perennials, such as Japanese maples, witch hazel, and delphiniums. The reddish-brown strands look especially natural on wooded properties. To get the most coverage, gently fluff the straw during application.

Cedar Chips

These large golden-brown pieces of cedar—up to 4 inches long—have a lot of ornamental appeal and take much longer to decompose than shredded material. The cedar chips’ natural oil gives them a clean, fresh scent and deters common insect pests. Fresh cedar can rob nitrogen from soil, so be sure to use aged chips in your garden. Because cedar chips lose color fast, you may be tempted to layer them on, but as with most mulches, don’t go above a 3-inch layer.

Straw

Use wheat straw to keep vegetable gardens neat in the summer and to insulate them against the cold in the winter (when as much as a 6-inch-deep layer is a good idea). Because it contains fewer weed seeds, straw is a better mulch than its close relative, hay. As it breaks down, straw reduces soil’s nitrogen level, so apply a nitrogen-rich fertilizer to counteract this process. This mulch decomposes rapidly, but is easy to obtain and inexpensive.

Cocoa Hulls

Cocoa Hulls iStock

Finely textured and uniform in appearance, lightweight cocoa hulls—the shells of cocoa beans— release a chocolatey scent as they decompose. Their rich brown hue darkens with age, adding contrast to your plant beds. In humid climates, a harmless mold may form on the hulls. To prevent it, layer the shells no more than 1- to 1 1/2-inches thick. Like chocolate, cocoa hulls are toxic to dogs. Look for varieties without theobromine — the chemical that dogs and other animals react negatively to.

Eucalyptus Mulch

Eucalyptus mulch is ideal for preventing weed growth and regulating soil temperature. It comes from a renewable resource—a fast-growing tree species found in the southeastern part of the country. The natural oils in eucalyptus mulch also emit a pleasant scent that keeps plant-chomping bugs at bay.

Melaleuca

A layer of melaleuca mulch can help save the environment—and discourage termites. Melaleuca is an exotic tree species that has overtaken Florida wetlands, and to limit the problem, environmentalists have encouraged grinding the invasive trees into mulch. A study at the University of Florida shows that melaleuca resists termites better than other wood mulches. This mulch is mainly sold in Florida.

Color-Enhanced Wood

In response to natural wood’s characteristic fading, manufacturers have created color-enhanced mulch, from rusty reds to chocolate browns to black. The wood is treated with plant-safe, water-soluble colorants, resulting in richer hues that won’t fade as fast. If colored mulch is made from recycled wood, make sure the wood has been screened for contaminants.

Wool

A flexible mat that’s especially good for hanging baskets, biodegradable wool mulch is made from wool-manufacturing waste to keep plants and soil properly hydrated. The fibers allow water to pass through, but absorb excess water to prevent root rot.

Recycled Glass

Like stone aggregates, pieces of tumbled glass recycled from old bottles and jars can be used for a natural-looking mulch with textural interest. Ranging in color from soft sea glass hues to rich jewel tones, this mulch can be used over landscape fabric, a synthetic fiber blanket, to thoroughly suppress weeds. Since glass can be a hassle to move, this mulch works best with established beds, such as foundation plantings. Also, only apply it in areas where it won’t be tossed around by lawn equipment.

Plastics

Studies show that plastic mulch sheeting, which warms soil as it reflects sunlight, may promote growth in seedlings and increase the yield of fruit and vegetable crops. The sheeting comes in several colors that reflect different amounts of light to benefit specific plants. For example, the light reflected by red plastic is said to boost tomatoes and strawberries, while green plastic is formulated to stimulate melon and cucumber growth. Silver plastic has been shown to repel pesky bugs. Because plastic mulch traps water around plants, it works best in cool temperatures.

Recycled Rubber

Low-maintenance rubber mulch, made from recycled tires, comes in a variety of vivid and natural colors. Because it doesn’t biodegrade, it doesn’t need to be replaced after its initial application. And because it’s not porous, a 1 1/2-inch deep layer is sufficient. Rubber is heavier than wood, so it’s less likely to blow or wash away—a plus in wind-swept areas or on slopes.

Synthetic Straw

Line sun-drenched beds with synthetic straw, made from recycled polypropylene. This durable mulch is treated with UV inhibitors to retain its earthy bronze hue for years. Occasionally fluffing the strands gives the straw a fuller appearance and lengthens its lifespan.

Buckwheat Hulls

As the outer layer of buckwheat seeds, these lightweight hulls—which measure just 1 millimeter in diameter—make for a finely textured, dark brown mulch that works especially well around rose bushes. It’s also recommended for use in smaller beds or container gardens, and should be applied in a layer no more than 1 ½ inches thick. To keep the tiny hulls from blowing away, sprinkle them lightly with water on a regular basis.