How to Use Mulch Effectively In Your Yard (and When Not To)

If you’ve got a yard, one of the first things you should put down is mulch. The versatile ground cover not only smothers weeds, reduces soil erosion, keeps dust down, and stops your yard from turning into a mud pit, it’s also one of the best and most important ways to restore your soil.

Why else should you use mulch?

• To make it harder for weeds to grow: Seedlings are smothered by the mulch layer and without light, some seeds won’t germinate at all.
• To keep moisture in: Mulch helps prevent evaporation, so you won’t have to water as often.
• To retain warmth and regulate soil temperature: Mulch offers insulation from cold and heat, protects plant roots from the damaging effects of extreme weather, and prevents frost heaving (where the soil expands and contracts from the continual freezing and thawing of water in the earth).
• To protect the soil structure: A layer of mulch can help reduce runoff during rainstorms and keep the soil from forming a hard pan (crust) in hot, dry weather.
• As a slow-release fertilizer: Many organic mulches release nutrients into the soil as they decompose.
• For decorative purposes: Mulches can be used to tidy up a bed and create a more cohesive look throughout the garden.

But how do you know what to use, and where? There’s an endless number of materials that can be called mulch, and the best one really depends on your use case. (Surprise: There are even instances where you should leave your soil bare. More on that below.)

Here’s what I’ve learned from personal experience and what I recommend for different types of areas. (You can find out more in my rundown of the best types of organic mulch to use.)

What kind of mulch to use for…

Annual vegetable beds

• Compost
• Straw
• Fall leaves
• Leaf mold
• Mushroom compost
• Black plastic

Perennial beds

• Wood chips
• Shredded bark or bark nuggets
• Sheep wool
• Pine needles
• Straw
• Compost

Flower beds

• Compost
• Wood shavings
• Wood chips
• Shredded bark or bark nuggets

Under shrubs and trees

• Wood chips
• Shredded bark or bark nuggets
• Pine needles
• Compost

Paths and large areas

• Wood chips
• Shredded bark or bark nuggets
• Pea gravel
• Crushed stone
• Burlap

Winterizing garden beds

• Straw
• Fall leaves
• Pine needles
• Grass clippings
• Plant debris
• Sheep wool
• Compost
• Animal manure

Containers

• Wood shavings
• Wood chips
• Compost

Living mulches

• Lettuce
• Carrots
• Beets
• Cilantro
• Parsley
• Creeping thyme
• Creeping oregano
• Alpine strawberries
• Yarrow
• Chamomile
• Sweet alyssum
• Trailing nasturtiums

What you should never use

I often see dyed wood chips spread across the front yards of newly built homes, and this is a hard no for me. Sure, that all-black (or red or dark brown) mulch might look slick at first, but the artificial color bleeds out over time and ends up looking terrible. Plus, I always wonder what’s in the dye…

The same goes for rubber mulch, which is made from recycled shredded tires. Kudos for finding a new use for tires, but on a hot day, your garden’s going to smell like a tire shop. There’s also the strong potential for leaching (of zinc, aluminum, cadmium, and chromium) and that’s probably not the kind of stuff you want contaminating your garden.

How (and how much) to apply

Start by determining how much you’ll need for your space. If you’re hauling in mulch from a nursery or landscape supplier, you can use a mulch calculator like this one to figure out how many bags, cubic feet, or cubic yards to buy. (It even lets you calculate mulch for odd-shaped beds like triangles or trapezoids.) If you’re signed up for a service like Chip Drop, be sure to make room for a truck to dump a large load on your property.

Once you have the mulch onsite, follow a few simple guidelines:

• Remove any weeds in the area first. They can be tenacious and will find their way through the mulch!
• If you’re starting seeds, it helps to apply a very thin layer of a light, fluffy mulch like straw or finely shredded leaves (no more than a quarter inch) to keep the soil surface moist until germination.
• For established plants, spread a 2- to 3-inch layer of mulch on the ground around your plants.
• Leave some breathing room. Mulch should always be kept a few inches away from stems and trunks.
• To prevent matting, especially with denser mulches like leaf litter, periodically fluff up the mulch (with a small rake or your hands) throughout the season.

When to apply mulch

Most organic mulches will last through an entire growing season and should only need to be reapplied in spring and fall. If you see that yours is starting to get a bit sparse (or has blown away), make sure to replenish it so that your soil is always covered with 2 to 3 inches of mulch. (More than that is unnecessary and in some cases, may even be detrimental to plants.)

In fall (after you’ve experienced a few frosts), apply a heavy layer of mulch to protect the soil from frost heaving, protect the crowns and root systems of overwintering plants, and prevent a crust from forming on the soil surface. As the mulch decomposes over winter, it feeds the soil and improves its structure.

The exact amount will depend on your climate. Milder regions may not need more than 3 inches to take them through winter, but colder regions can use as much as 8 inches (particularly over fall-planted garlic, cold-hardy overwintering herbs, or perennial herbs, vegetables, and flowers).

Even if your garden is empty, you should still throw on some mulch—never leave the soil bare over winter, if you can help it. That’s because soil nutrients can be depleted by heavy rains, and mulch works to reduce leaching and surface water runoff, keeping the soil structure intact.

Is too much mulch a bad thing?

Yes, I know I just said three paragraphs ago that too much mulch can be detrimental, but that’s only true of actively growing plants, which need access to oxygen and water.

In fall and winter when perennials go dormant, their root systems need to be protected from desiccating winds and freezing weather. Mulch helps hold in moisture (so plants stay hydrated despite cold drying winds) and keep the soil from uprooting plants during repeated freezes and thaws.

Once the weather begins to warm up in late winter to early spring, you can start to thin out the mulch to increase airflow to the soil and roots. Which leads me to the last point…

When to leave your soil bare

Yes, there are times when you might actually want to keep your soil exposed. In spring (particularly if you live in a cold or rainy climate), you should lift all the winter mulch and leave your garden beds uncovered to warm up and dry out so the soil thaws and becomes “workable.”

Removing the mulch also encourages slugs and other insects that overwintered in your garden beds to move out. (Otherwise, they’ll continue to make themselves comfy in the moist, dark recesses of your mulch and help themselves to all your tender new seedlings.)

An empty garden bed also makes it easier to sow seeds. Once your seedlings grow a few inches (past the delicate seedling stage) and the weather turns drier, you can add your favorite mulch again.