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Monday, December 14, 2015

Use dead leaves the way nature intended

Sooner or later, you’ll get tired of moving fallen leaves from one place in your yard to another. Maybe you end up stuffing them into plastic bags or you decide to call a mound of leaves a "compost pile." Here’s an idea: instead of using a rake, use your lawn mower to improve your soil and get fallen leaves out of sight.

The easiest and most environmentally sensible thing to do is leave the leaves where they fall, and shred them up with your mower. No special mower or blade is necessary; just do it like you’re cutting the lawn. By far the worst thing you can do is rake up all the fallen leaves, leaving bare ground exposed to the elements. This just encourages unwanted vegetation and erosion. A thin carpet of shredded, dead leaves protects the soil from compaction and erosion; and it’s free! It also loosens the soil so it holds water better.

Most of the trees in north Texas are oak trees. All spring and summer, oak leaves store up nutrients gathered from the soil. These nutrients are roughly equivalent to the nutrients in store-bought compost, which we'll gladly pay good money for! About now, however, leaves are dying and falling to the ground. Then they start decomposing naturally, becoming compost. They’re also releasing all of that stored nutrition. (It's a natural, yearly cycle that nature intended.) This coming winter, the dead leaves will protect fragile roots (which are usually near the surface) from the cold. 

Taking the dead leaves away interferes with this natural process and stresses plants, which now have no natural source of nutrition or natural protection. Left in place, however, fallen leaves slowly decompose into an excellent soil ingredient; leaves mixed with your soil will immediately start decomposing to nourish and loosen the soil and noticeably improve plant growth. 

Biology is certainly not my strong suit. However, I'm told that fallen leaves contain carbon and nitrogen compounds, which all plants crave. What's more, some organic compounds (such as amino acids) resulting from leaf decomposition can be absorbed directly by plants, for more vigorous growth.

The only drawback that I know of is that sometimes too many leaves can form a mat and smother plants, cutting them off from sunlight, air or water. Of course, if you shred your leaves into little pieces with your mower, this isn’t a problem. No mat will form, your lawn will green up earlier in the spring and it will resist browning in the heat.

You’ll be amazed by the way your leaves nearly disappear when you shred them. They’ll take up around ten percent of the space that unshredded leaves do. Many pieces will simply filter down between the grass blades and start decomposing and releasing nutrients right way, instead over the next decade. This lets you skip one of your yearly fertilizer applications.

Leaves can, and do, come to rest in the wrong places sometimes. So if they're on your driveway, sidewalk, porch or deck, by all means rake or blow them away. But when they fall on soil (including your lawn), look at them as a free gift from nature, chock-full of nutrition for your plants, not as a future chore. Those dead leaves should be used as nature intended, not thrown away, burned or sent to the landfill.


Owen Yost, in addition to blogging, is a Landscape Architect emeritus from here, whos
worked in north Texas for over 30 years.  He is a member of the American Society of Landscape Architects (ASLA), International Society of Landscape Architects, the National BirdFeeding Society, National Wildlife Federation and the Audubon Society. He was honored with a Lifetime Achievement award by the Native Plant Society of Texas. His design office is at