We all love the look of Mulch….but sometimes it can do more harm than good.

Do you have a thing for the finished look of freshly mulched flower beds?  You’re not alone. Each year homeowners spend hundreds of dollars on mulch.  That’s not all - you need to account for what you might pay for the labor to spread it and clean up.  

An ideal mulch product mimics nature by covering plants with organic matter that provides nutrients and beneficial microorganisms to the soil.  You probably use mulch to suppress weeds, but mulch does much more: it retains moisture, controls erosion, and moderates fluctuating soil temperatures in our plant’s root zones. When properly applied, at the right time and depth, it naturally enhances the soil and plants with the gradual decomposition of organic matter.  A thin layer of about 2 inches is all you need to achieve these benefits, plus add uniform color to your garden.

​To save you time and money, avoid these ten common mistakes:

1.  Volcano Mulch:
This looks exactly like it sounds—a deep pile around the base of a tree trunk.  This type of mulching causes the lower trunk to become waterlogged and eventually compacts and interferes with oxygen reaching tree root cells.  Volcano mulching decays the tree’s bark and harbors rodents that chew on the base of the tree.
Better choice: Keep mulch away from the base of trees. (PSU Mulch Fact Sheet)

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2.  Using Fabric and Plastic Weed Barriers:  These don’t work to keep weeds away and have negative side effects.   These materials strangle plants, which require space to grow. These barriers also negate aeration and prevent the absorption of decomposed organic material.

Better choice:  Don’t use weed barrier at all. Or remove the existing one.   Use natural mulch.

Read our last blog for more information read about the negative impact of using landscaping fabric on soil. ​

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3. Poor quality mulch:  Cheap or free mulch, especially from landfills, can be very tempting, but it can be f​ull of pesticides, dangerous tree diseases, pests, and weeds.

Better choice:  Use a trustworthy supplier who offers a mulch that contains shredded bark, wood from trees, decomposed matter, and aged manure.

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4.  No Mulch: Gardens that have no mulch will dry out more quickly, get compacted, fail to adequately nourish plants, promote the germination and spread of weeds, and erode more quickly.

​Better choice: Mulch or use ground cover plants.  Once established, dense ground cover smothers weeds, casts shade to keep the ground cool, draws rainwater into the soil (particularly beneficial on a slope,)  and is low maintenance. When ground cover fills in, no mulch is necessary. 

For a list of excellent ground covers check out Blue Stone Perennials.  This is unsponsored.  I order from them every year, and if you live close to Cleveland check out the amazing annual June sale.

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5. Using the same mulch depth for all plants. Too thick a layer of mulch inhibits the movement of air and moisture into and out of the soil.

Better choice:  Follow the appropriate mulching depths for your plants.
    

Recommended depths: 
3-4” for woody plants, keeping it away from trunks.​

2-3” around herbaceous plants and keeping mulch away from crowns.

NEVER exceed 4” of mulch. ​​

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6. Do not use uncomposted wood chips as a mulch near houses or along driveways where vehicles will be parked. This kind of mulch provides ideal growing conditions for a troublesome fungus called "artillery fungus." The artillery fungus shoots spore masses that stick to vinyl siding, automobiles, and other objects. The dark spore masses, each up to 1/16-inch in diameter, are extremely difficult to remove and can be very unsightly. 
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Better Choice:  Blend mushroom manure and mulch.  Penn State researchers have discovered that blending 40 percent used mushroom compost with landscape mulch greatly suppresses the artillery fungus. Mushroom compost, or mushroom soil, is the pasteurized material on which mushrooms are grown.

Artillery Fungus

Spores on Siding

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7. Cocoa bean ​mulch smells good and is organic, but is toxic to dogs.

​Better choice:  Use another type of mulch.

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8.  Dyed Mulch, which unfortunately has become highly popular, may contain demolition debris and also be contaminated with lead paint, pressure treated wood, or other toxic substances. (More information further into this blog)

​Better choice: Use organic mulch.

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9.  Using chemicals to eliminate weeds and grass for future planting beds. Chemicals harm the environment, our bodies and soil.
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Better choice: Lay down newspaper under soil and mulch to kill grass and weeds.

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10. Inorganic mulch (plastic, rubber, etc) does not contribute to soil or plant health and is usually more ecologically harmful to produce and transport.  Products such as shredded tires are intended to provide a soft surface under playground equipment. It should never be applied to garden beds. As with landscaping fabric, leaf debris and other organic material cannot decompose into the soil.  Plastic pieces and rubber also increase the heat of the soil, which may damage plants or affect the time plants go dormant in the fall.

​Better choice:  Use local natural mulch.

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Mulch Quality

Did you ever think that your organic garden just might be topped off with a nice, thick layer of arsenic or chromate copper arsenate (CCA for short) or any one of many not-so-organic chemicals? The potential health risks are sobering and beyond the scope of this mention.

 In 2004, the mulch and soil industry adopted standards prohibiting the use of CCA-treated wood in all consumer mulch and soil products. The Mulch and Soil Council (MSC) also developed a Product Certification program to help consumers identify mulches and soils that comply with industry standards and contain no CCA-treated wood.  Certified mulches and soils can be found at major retailers and garden centers across the country. They are identified by the MSC Certification Logo on the package and are listed on the MSC Web site.

MSC Certification Label

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Dyed Mulch

Colored Mulch can be toxic, bad for plants and harmful to children.
Most colored mulches are treated with harmless dyes, like iron oxide-based dyes for red, or carbon-based dyes for black and dark brown. Some cheap dyes, however, can be treated with harmful or toxic chemicals. This is pretty rare though, and most often, it is not the dye itself that is of concern, but rather the wood in mulches.  Generally, if the price of dyed mulch seems too good to be true, it probably is not good at all. Spend the extra money for better quality and safer mulch. While most natural mulches, like double or triple shredded mulch, cedar mulch or pine bark, are made directly from trees, many colored mulches are made from recycled wood – like old pallets, decks, crates, etc. These recycled bits of treated wood can contain chromates copper arsenate (CCA). Using CCA to treat wood was banned in 2003, but many times this wood is still taken from demolition sites and recycled into dyed mulches. CCA treated wood can kill beneficial soil bacteria, beneficial insects, earthworms and young plants. It can also be harmful to the people spreading this mulch as well as animals who dig in it. 

Safety of Dyed Mulch in the Garden 
Besides the potential dangers of colored mulch for pets, people and young plants, dyed mulches are not beneficial for the soil. They will help retain soil moisture and help protect plants during winter, but they do not enrich the soil or add beneficial bacteria and nitrogen as natural mulches do. Dyed mulches break down much slower than natural mulches. When wood breaks down, it requires nitrogen to do so. Colored mulch in gardens can actually rob the plants of the nitrogen they need to survive.

Read more at Gardening Know How: Is Colored Mulch Toxic – Safety Of Dyed Mulch In The Garden​

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Buying Mulch

Any organic material can be mulch, including ground-up leaves, compost, buckwheat hulls, ground-up bark, lawn clippings, wood chips, bark nuggets, or even stone. Bark mulch is the most common, but lighter mulches like buckwheat hulls and compost are better for perennial beds.  Shallow-rooted perennials do better when they don't have to compete with heavy mulch for micronutrients in the soil.

Whatever material you buy, make sure it contains no weed seeds.  Or later in the summer, you'll be in for a big surprise. If you're buying compost or horse manure, be sure it's aged (about 4-6 weeks,) or it can burn your plants. If you're worried about termites, use a mulch that has little or no actual wood in it. (Bark doesn't attract termites — it's the wood they feed on.)

How much should I purchase?
A yard of mulch will cover 100 square feet when spread 3 inches thick. Measure carefully, and buy only what you need. There's nothing more frustrating than paying for something and having a large pile of it left over.  To calculate the amount you need, use Lowe's  calculator.

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When to Apply Mulch

According to the Ohio State University Extension Office, the first round of mulch is normally applied in spring after the soil is warmed and has dried up somewhat from winter rain and snow. This is normally in the middle or late spring season—perhaps early May. If there is more rainfall than usual, or temperatures stay cool longer than usual, it may be best to delay mulching even until late May or early June.  Some gardeners or landscapers may choose to apply another layer of bulk mulch in fall as well. This is often done when growing annuals or fall-planted bulbs as it will help protect against the cold of winter.

Some like to mix compost into the mulch and a 1:4 ratio is good.  However, it may be better to mix the compost into the top layer of soil, then mulch. This way, you are amending the soil, not the mulch.  Often weed seeds develop in the mulch and the mulch breaks down faster when there is manure mixed in. By applying compost or manure under the mulch, you may be able to delay mulching to every two years.

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Wood  Mulch vs. Rock Mulch
(Unsponsored Information from Davey)

PROS

• Low Maintenance: You almost never need to replace them.
• Lower Cost: Because they’re longer lasting, it is generally less expensive to mulch with rocks.
• Fire-Proof: If you live in an area with wildfires, rocks could be better since they’re non-flammable.
• Weeds Be Gone: Rocks can keep weeds away longer.
• Wind-Resistant: Heavy rocks are great at preventing soil erosion in windy areas.
• Perfect for Rock and Cacti Gardens: Rocks are just right for these garden spaces!

 
CONS

• Too Hot: Rocks, especially lighter ones, raise the soil temperature, leading to stressed and thirsty plants. 
• No Benefit to Plants: Rocks don’t aid plant growth or soil health.
• Messy pH: Most trees prefer acidic soil, but rocks create alkaline soil, which can hurt trees.
• Return of the Weeds: Wind will eventually blow soil between rocks, creating a spot for weeds to grow.  Navigating through rocks to pull weeds is very challenging.
• No Good for Pruning: Rocks can prohibit rejuvenation pruning, creating unwieldy shrubs.
• Remove by Hand: If you want to remove stones, you must do it manually, which can be tedious!

VERDICT:  Mulching your garden reaps benefits throughout the growing season.  But what you use makes all the difference.  Seek out a local supplier.  Ask about the ingredients of their mulch.  When buying bagged mulch, look for the MSC product certification.  Never buy dyed mulch and never volcano mulch. And finally, remember that organic mulch is overall better than stone.  But stone is better than no mulch at all.