By Marion McParland and Will Sulahian

As we celebrate Earth Day — a day to focus on the health and well-being of our planet — we at PHS believe that everyone can play a part in creating and maintaining a healthy environment that celebrates our great planet.  Let’s consider mulch in our discussion: an estimated $1 billion is spent every year to cover soil in this country, for both aesthetic and environmental reasons. But not all mulch is created equal. In fact, some may be harmful to your plants and the environment. This Earth Day, discover small-scale changes to your mulching habits that will help you grow healthier plants, and improve the environment overall, with organic, natural choices. 

What is mulch?  

Mulching is done to prevent weeds and make a garden look tidy and manicured. Mulch is a broad term for any soil covering — straw, shredded hardwood, or leaf compost. While mulch is primarily made of organic materials like tree bark, wood chips, pine straw, moss, grass clippings, or leaves, some may contain newspaper or recycled tires. Mulch made from treated wood can contain chromated copper arsenate, a form of arsenic. And some may be treated with herbicides to help prevent weed growth. Dyed mulch is detrimental as well, since rainfall can spread the dye into yards, driveways, and waterways. All of these unnatural elements are harmful to our environment. 

Looks Aren’t Everything 

A mulched front yard looks great after a long winter! But before you mulch this year, we encourage you to learn natural alternatives that will create the same beautiful outcome yet be gentle on the Earth. While traditional mulch may look nice on the surface, you may be doing more harm than good. Organic mulching is the way to go. “When you look at a forest, you can see that the leaves on the ground are naturally mulching. We want to recreate what nature is already doing as much as possible,” says Tim Majoros, Director of Public Landscapes at PHS. 

Leaf Mold as Mulch for Trees, Vegetables, and Flowers 

Leaves make the finest mulch because of their origin. Trees are deep-rooted — absorbing minerals from deep in the soil. The leaves of most trees contain twice as many minerals as manure, including calcium, magnesium, nitrogen, and phosphorous. Use leaf mold to improve soil in both vegetable and flower gardens.  

Make leaf mold yourself. Gather leaves shortly after they have fallen when they are at their nutrient best, then run the mower over them a few times to shred. Rake leaves into an enclosure lined with plastic and cover it when you are done to conserve the moisture. It takes three to six months for leaves to decompose and be ready to use.  

Living Groundcover  

Living groundcover acts in the same way traditional mulching does, but instead consists of living plants used as groundcover to prevent weeds and nourish the soil. This sustainable practice produces more nitrogen. Living annuals and perennials planted among your existing plants will shade the soil and suppress seeds while they are living. 

Best perennial choices include rhubarb, thyme, oregano, white clover, and legumes. These plants will provide nutrients and feed the soil underground while growing. Additionally, Asarum canadense, ‘Canadian wild ginger',  Carex pensylvanica ‘Pennsylvania sedge’, and Chrysogonum virginianum, 
‘golden star’ (pictured above) are also great choices. Living groundcover will help retain soil moisture, as well as suppress weeds and fight diseases plants can face.  

Learn More 

This season, we at PHS encourage all planet-dwellers to move away from conventional mulching practices and focus on natural and impactful solutions for your soil and plants. Using these methods will help create a healthy living environment. PHS is here to support your gardening journey with resources and workshops. Learn more about the importance of soil health in this upcoming webinar, “It All Comes Down to Soil” on May 10.