Leave the Leaves
Fall is a time of brilliant yellows, oranges, and reds adorning the trees and blanketing the ground with color. It is also the time of year that many people drag out their rakes and leaf blowers to remove all that summer growth. There is good news for those who dread this annual chore: don’t do it! The best practice for the health of the plants and the animals living among us is for us to leave the leaves as mulch for our yards.
How to mulch your leaves:
Leaf mulch can be used to enrich and protect the soil in plant beds, vegetable gardens, and lawns. If leaves are shredded first, they will break down faster. This step is necessary for using leaf mulch in lawns.
For lawns:
Mulch mow leaves directly into the lawn. You can use a regular mower or attach special mulching blades, which can be purchased for less than $20. Many mowers are already designed to mulch cut grass and can be used to mulch mow leaves as well. Put the mower on its highest setting and run it over the leaves. Sometimes a second pass is needed to shred them to a small enough size. This is best done when leaves are dry. If the volume of leaves is too much for the lawn, collect some with the mower’s grass catcher or just a rake and tarp, and spread them in plant beds.
For perennial beds and vegetable gardens:
Leaves can be directly raked into plant beds or shredded first. A mower, leaf shredder, or chipper can be used to break leaves into smaller pieces so that they break down faster as mulch. Mulch provides protection throughout the winter. If whole leaves are used, they may need to be pulled aside in the spring to allow more delicate perennials to emerge. These plants can break through the mulch if the leaves are shredded first. If you do not like the look of leaves in your landscaping, consider adding a 3” layer of leaf mulch and covering that with a commercial mulch of your choice.
Mulch piles:
Alternatively, create leaf piles in a back corner of your yard. To prevent leaves from blowing away or to create a neater pile, contain it in a composting bin that still allows water and air to reach the leaves as they decompose. This can be built easily with a ring of chicken wire. Use the finished mulch in your plant beds, vegetable garden, potted plants, and around shrubs and trees. Leaf piles are a great resource for birds, too—you may see robins tossing through the leaf pile foraging for worms and insects.
Why this is important:
The process of removing leaves can be harmful to soil and air quality. Plants need sunlight and water to grow but also other nutrients that they extract from the soil. The process of decomposition returns those nutrients to the soil where other plants can use them. Decomposed leaves also add structure to the soil, which improves water retention and the soil’s ability to handle droughts and flooding events (which will only increase with climate change). When we remove leaf litter, we are depleting the soil of these essential nutrients and structure. As a result, we find that we need to add extra fertilizer and must purchase mulch for our plant beds. Leaf mulch suppresses weeds, helps retain moisture, and protects plant beds during the winter.
Leaf mulch also provides cover and nutrients for animals. Bird and insect populations are declining at an alarming rate. We can support these animals by providing areas of leaf litter. Many insects, including caterpillars of moths and butterflies, overwinter in fallen leaves. Detritivores such as worms and pill bugs help break down leaves into the nutrient rich soil that plants need. All these animals that find shelter in the leaf litter are in turn food for other animals, particularly birds. Leaves left in perennial beds, particularly around shrubs and trees, help protect biodiversity.
Finally, the practice of blowing leaves out of the landscaping using gas-powered leaf blowers can be particularly detrimental to plant beds. The high-force winds produced by leaf blowers scour plants, compacts the soil, and blows away precious topsoil with its nutrients. Gas-powered leaf blowers are also a source of air pollutants, emitting carbon monoxide, nitrogen oxides, and particulates into the air. These models also create noise at high decibel levels and low frequencies that can penetrate walls. These impacts are detrimental to the health of both humans and wildlife. Mulching your leaves eliminates or decreases the time spent using leaf blowers and can be accomplished with less environmentally harmful tools, such as rakes, tarps, and brooms.
As we close out another summer of extreme weather, we are reminded of how the choices we make, big and small, can have a major impact on our environment. Please consider “leaving the leaves” this fall and help restore the ecosystem that supports you. Have a conversation with your landscaping company, if you use one, or take action yourself. You can improve biodiversity and save time and money by taking advantage of this incredible resource in your yard!
Susie O’Donnell
Swarthmore Environmental Advisory Council
aFewSteps
Elizabeth Jenkins
Swarthmore Environmental Advisory Council
Margaret Betz
Swarthmore Environmental Advisory Council
Sources:
www.LMHealthyYards.org
www.leaveleavesalone.org
Banks, J.L and R. McConnell. 2015. National Emissions from Lawn and Garden Equipment. EPA: Session 10 - Speciated Emissions Data and Their Use (2015 EIC)
