Leaves of red, yellow, orange and green color the autumn landscape with their vibrant, dramatic hues, compelling us to pull on soft, warm sweaters, pour a mug of hot cider and curl up with a good book. But when they leave their branchy homes and gently sway to the ground, the compulsion to grab a rake and head outdoors for hours of back-breaking labor erases the tranquility almost immediately. Why not just let them be?
For starters, if left in place until spring, those leaves will smother your lawn, depriving it of sunlight and air. And when the soggy, matted debris is cleared away, you’ll be left with dead patches that will require reseeding. And that’s the best-case scenario: Diseases like snow mold and brown patch, and all sorts of fungi thrive between leaf and lawn, and you’ll find dealing with the aftermath is even more burdensome than raking would have been.
But there is one way you can leave your leaves and have your lawn, too: Mulch them. This is easier than it sounds, as it simply requires running your lawn mower over the leaves to shred them into little bits to prevent clumping. The Sonoma County Master Gardeners say you could also toss them into a shredder. Or, if they are still dry, you could crumble them with your hands as you spread them around.
Then, the master gardeners say, rake them on to your beds in the fall. They will soften the heavy rains’ effects on your soil, and they will protect your plants during freezing temperatures.
Local experts say that even though they are not as attractive as bark, leaves are porous and decompose quickly, enriching the soil.
Those bits will work their way between grass blades to the soil line, where they’ll gradually decompose and even add nutrients to improve the health of your turf.
If there are too many to leave on the lawn, you can run the mower over them and move the resulting mulch to your garden beds, where they’ll serve the same function.
Mulching leaves isn’t only easier than raking — it’s more environmentally sound. Bagged-up yard debris adds nearly 33 million tons of solid waste to U.S. landfills each year, according to the Environmental Protection Agency. And its decomposition under those conditions (without adequate oxygen) can result in a release of methane gas, which tends to heat up when exposed to sunlight and can result in a too-warm atmosphere — and that’s not good for plants, wildlife or us.
The only fertilizer an established oak needs is its own organic leaf litter for mulch. Keep leaf litter in place, just not up against the trunk. Mulching conserves water, helps moderate ground temperature, improves soil structure and increases organic matter.
Oaks are among the most common trees found in North Coast landscapes. And a perfect mulch for oaks are their oak leaves. The Napa County Master Gardeners advise you to leave the leaf litter of oaks in place. Just make sure it is not up against the trunk.
Another problem caused by ignoring your leaves is that many of them would be carried by wind to our waterways, where they’d release excess nutrients and can throw the whole ecosystem out of balance.