By Kathy Torres

The National Wildlife Federation has designated October as Leave the Leaves Month. Since we are beginning the month of November, you may be thinking that we have missed the boat, however, because the leaves typically fall a little later here in the South, it’s not too late to begin this practice in the landscape. If you’re of the opinion that this just doesn’t make sense… leaves are messy and should be completely removed, just pause a moment and consider that by raking up the leaves, you are eliminating a habitat for many little creatures that overwinter under them or rely on them for materials to build their winter homes. Leaving the leaves also has other benefits like the addition of nutrients and moisture preservation to the soil, and environmental effects.

Some of the ’little creatures” finding shelter through the winter by leaf cover are birds, box turtles, salamanders, toads, and frogs. Many invertebrates like fireflies, bees, butterflies, and moths make their cold-weather homes in leaf litter. “Leaving the leaves isinvesting in the future generation of pollinators,” says Clay Bolt, manager of pollinator conservation and communication at the World Wildlife Fund-US.¹ Providing beautiful flowers for butterflies is a great way to ensure their existence in the yard in spring and summer, however, it’s important to provide a habitat for the entire butterfly and moth lifecycles. These insects, especially in the caterpillar stage, are also a crucial food source for adult birds and nestlings, as well as many other friendly garden neighbors like frogs, salamanders, skinks and lizards. Leaving the leaves will help butterflies to provide food in the ecosystem and to complete their lifecycle.

So that you really understand the actual effects that creating a leaf layer in your landscape beds can provide, these examples will bring you “up close and personal.”

The Luna Moth is often considered one of the most attractive moth species in North America, relying on leaf layer for their pupal stage during winter hibernation. The journey begins when the female luna lays her eggs on the leaves of a deciduous host plant while the leaves are still on the tree. Typical host plants for luna moths are white birch, walnut, hickory, or sumac. When the caterpillars hatch, they feast on the leaves, growing and preparing for the next phase of life. When metamorphosis begins, the luna caterpillar spins a protective silk cocoon incorporating the very leaves she’s been feeding on into the cocoon. As autumn progresses and leaves begin to drop, the cocoon falls to the ground. In the accumulating leaf layer, it finds camouflage and protection, safely hidden away from potential predators. Moisture retained in the leafy blanket is crucial for development of the moth. Without it, pupating moths will lose weight rapidly and will produce fewer eggs after emerging as adults. Luna is not the only moth dependent upon this environment. Actually, 94% of moths pupate in cocoons in this way.

The Eastern Box Turtle has an interesting relationship with leaf layer in our gardens and forests. Typically, they are active from April to October, often finding old leaves to camouflage the soil depression where they have laid eggs. As winter approaches, they begin their brumation (a type of hibernation specific to reptiles). This takes place just below the soil surface, usually no deeper than 2-6 inches. A leafy blanket offers them insulation needed to survive as temperatures decrease, even down to a chilly 31°F.

Yellow-Faced Bumble Bees, like most other bumble bees, operate in small colonies that follow a one-year cycle. As summer fades and temperatures drop, a dramatic shift occurs within the colony. Workers and males, having played their roles, will perish with the onset of winter. Only newly mated queens will survive until the following spring. Survival for these queens depends on finding a safe place to endure the cold months. Leaf piles provide a hibernation site as the queens burrow down just a few inches below the soil surface. Insulation provided by leaf cover is critical to survival and the ability to continue the life cycle when they emerge in April or May. Each queen is responsible for establishing a new colony, which can house up to 300 worker bees at a time. The loss of even a single overwintering queen can mean the absence of an entire colony the following year. Because bumble bees are incredibly efficient pollinators, the potential impact on plant pollination is extremely significant.

Did you see Fireflies lighting up your backyard this past summer? Probably not, and that’s because you likely bagged up all those fall leaves and put them by the side of the road for the garbage collector. Unknowingly, you removed all the juvenile fireflies from your yard too!

Fireflies, who are beetles, live the bulk of their lives (95%) as larva in leaf litter, under rotting logs, and in moist areas where they can thrive. The larvae are eating machines, devouring many soft-bodied insects, typically the gardener’s foes: slugs and snails. For this reason alone, they are worth protecting and encouraging in our gardens. The beauty they bring as adults on a hot summer night is a wonderful bonus.

In areas where trees are growing, a leaf layer 2-5 inches deep may occur naturally. By leaving the leaves in place a few feet out around the trunk or in a bed with shrubs, mulch is formed. Some may blow away on a windy day, but the more frequent rains that we get during the winter months will help them to stay in place and eventually break down to about 2 inches of mulch.

Be careful not to over-mulch. Repeated layers of hardwood mulch or pine straw in spring along with fall leaves may create a mulch that is too deep. In that case, it is better to rake away the fall leaves to avoid impacting the natural ecosystem. Another exception to allowing fall leaves to remain is on the lawn. It is NOT recommended to allow dense coverings of leaves to stay on your grass as it will likely cause fungus or grass roots to rot. It is, however, ok, if you use a shredding lawn mower, to allow them to sink down into the grass. This process actually adds nutrients to the soil.

Keep in mind, when considering this practice… you DON’T WANT to use diseased leaves as mulch because this may spread disease to healthy plants. Remove and bag diseased leaves whenever possible.

The U.S. Environmental Protection Agency reports leaves and other yard debris account for more than 13 percent of the nation’s solid waste (33 million tons a year)! Without enough oxygen to decompose, this organic matter releases the greenhouse gas methane. In fact, solid-waste landfills are the largest U.S. source of man-made methane, and that’s aside from the carbon dioxide generated by gas-powered blowers and trucks used in leaf disposal.²

To summarize the reasons to consider leaving the leaves, here are the benefits:

1. Provides needed habitat for wildlife
2. Adds nutrients and moisture to the soil
3. Reduces greenhouse gas
4. LESS RAKING

Being a naturalist is very much in style these days, and there are certainly many ways to participate in this effort. One easy way is to consider leaving the leaves. Taking care of the planet and its inhabitants is always worthwhile and at the forefront of this objective. Like most activities in our everyday lives, we adapt a change in our habits and practices to fit individual needs. You may have more leaves falling in your yard than necessary to make a 2-inch mulch around all the shrubs and trees. In that case, consider a compost pile for the extra. Click HERE for Clemson’s Home and Garden Fact Sheet on composting. You may not have a lot of leaves (with the exception of those that blow in from your neighbor’s yard). Instead of fussing about it, put those leaves to good use by using them in your beds. Here’s where you may need to do a bit of raking. So, go ahead and get outside on the next cool, sunny day. Happy Fall Y’all!

There’s always something blooming at Wingard’s!

¹The Surprising Benefits of Leaving Fallen Leaves in Your Lawn, According to Experts
²Why You Should Leave the Leaves