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8 types of mulch for your garden and how to use them

  • 3 min to read

Mulch can be a multitasking helper in the garden, something that smothers weeds, insulates plants from cold temperatures and prevents soil erosion.

Used the wrong way, though, mulch can foster diseases, house rodents and might even kill plants and trees.

Follow this mulch guide to get the most from your mulch. The tips come from the agricultural extensions of Cornell and Penn State universities.

Bark mulch

Pros: Resistant to compaction. Widely available.

Cons: Fresh bark can leach toxins which can kill young plants. Seasoned bark is less likely to harm plants.

Did you know? If possible, resist the temptation to use dyed mulch, which can leach poisons into the soil and damage new plants.

Sawdust

Pros: Great for blueberries, rhododendrons and acid-loving plants like evergreens.

Cons: As it decomposes, sawdust can rob the soil of nitrogen.

Did you know? Sawdust decomposes fast, creating compaction, so it needs to be renewed annually.

Cocoa hulls

Pros: Byproduct of the region’s chocolate industry. Strong chocolate aroma.

Cons: Can be toxic to plants and dogs.

Did you know? When eaten by dogs, cocoa mulch can cause problems similar to chocolate poisoning. The American Veterinary Medical Association advises: “Pet owners avoid use of cocoa bean shell mulch in landscaping accessible to unsupervised dogs, or at least use it cautiously around dogs with indiscriminate eating habits.”

Straw

Pros: Inexpensive and effective.

Cons: Highly flammable. Contains grain seeds that germinate. Easily blown away by wind.

Did you know? Straw is the stalk of a grain like wheat, oats or rye. Hay is the entire plant, including the seed head, and is used as animal feed, not plant food.

Leaf mulch

Pros: Easy to find. No cost if you have trees. Feeds plants as it decomposes.

Cons: Whole leaves can become matted into layers that trap air and excess moisture, which can damage plants and create space for ice.

Did you know? Shred leaves with a mower to create leaf mulch less likely to become matted.

Stone/rock

Pros: Not blown away by wind. Doesn’t harbor diseases or contain weed seeds. Wide variety in size and color. Good for succulents and xeriscapes.

Cons: Rocks easily migrate into soil or away from flower beds. Can be too hot for some plants.

Did you know? Limestone chips raise the pH of soil and shouldn’t be used on acid-loving plants.

Plastic

Pros: Good at suppressing weeds, retaining soil moisture and warming soil.

Cons: Prevents water from entering the soil. This can be minimized by alternating with bare ground.

Did you know? Plastic is a good mulch for spring-seeded crops because it increases soil temperatures. Black plastic increases soil temperatures by about 5 degrees and clear plastic by 7 degrees to 13 degrees.

Fabric

Pros: Blocks weeds quickly for annual planting beds. Allows water, fertilizer and oxygen through.

Cons: Degrades quickly and is usually paired with another type of mulch, preferably inorganic, like rocks. Some weeds like grasses can grow through the fabric.

Did you know? Any soil or organic material on top of fabric mulch will encourage weed growth.