Got leaves?
And how do you feel about that?
Leaves are a fact of life in the Northwest, and their beauty and usefulness is balanced by their potential nuisance. They can enrich the soil or kill the grass. They color the world but increase our risk of trip-and-slip.
Here’s more than you ever wanted to know about leaves: what they are, what they can do for you and your landscape — and how to get rid of them responsibly.
Up in the air
A leaf is a solar panel. A tree covered with leaves is a powerful solar farm.
Up in the air, leaves are perfectly positioned to sponge up sunlight. They are full of the pigment chlorophyll, which absorbs red and blue light wavelengths while bouncing back green light — which is why nature looks so green to our eyes.
The light leaves absorb is combined with other ingredients absorbed from the air (carbon dioxide) and the roots (water and dissolved minerals such as nitrogen) to make glucose in a process called photosynthesis. Glucose is a natural energy source used by many living things, including humans — although we can’t make it from sunlight.
Humans also use the main byproduct of photosynthesis: oxygen. Tiny pores, called stomata, are how leaves exchange carbon dioxide and oxygen in the air, according to Britannica.
In autumn, as days get darker and temperatures get colder, deciduous trees move toward winter dormancy. Nutrients in the leaves move into the trunk and roots. Chemical and structural breakdowns in leaves result in those vividly changing colors and eventual drops to the ground.
“Dropping them gives the plant a fresh start in the spring,” according to Britannica, “and the nutrients from the decaying leaves are recycled to help grow the next leafy generation.”
But evergreen trees — so plentiful here in the Pacific Northwest — protect their leaves and needles with their own thick waxes and resins, according to Brittanica.
On the ground
Leaves on the ground are so controversial. When the ground belongs to you, that is.
Seems like it’s the American way to sweep up one’s lawn so it looks like a green carpet. That takes a lot of work — and a lot of harmful chemicals.
The pristine-turf mindset is changing these days, with some expert nature lovers recommending that you leave your lawn intentionally messy. Nature has devised its own perfect recycling system, they say, with leaves falling directly down from the crown onto that tree’s root area. Why interfere?
Because life isn’t quite so simple. Just leaving leaves all over lawns can smother grass and let weeds flourish, warned Master Gardener coordinator Erika Johnson of the Washington State University Clark County Extension. Johnson suggested trying the following.
- Rake whole leaves off your lawn and into garden beds and bare patches.
- Find a bare patch or two to build big leaf piles, and just let them be — your gifts to birds, bugs, worms and other little critters that help keep your landscape healthy and thriving.
- Mow over leaves on the lawn and leave them there in chopped-up little bits that will decompose quickly.
“Leaves are friends,” Vancouver urban forester Charles Ray told The Columbian in 2021. “Leaving leaves in landscape beds and around the base of trees promotes healthy soils by nutrient cycling, helps retain moisture and is a natural weed control.”
Your health
While tree and wildlife lovers may encourage greater lawn laziness, human health experts like a little raking.
In a recent article called “Exercise with a purpose,” the Harvard Medical School said that many lawn-and-garden work activities — raking, weeding, composting, planting and mowing — all qualify as “moderate-intensity exercise” or better. The U.S. Department of Health and Human Services recommends that everybody get at least 150 minutes per week of moderate-intensity exercise.
In addition to strengthening the heart and lowering blood pressure, raking and gardening can be a workout for all the major muscle groups, along with build flexibility and strong joints, according to The National Gardening Association. (Raking can also hurt your back, so don’t overdo it.)
The LiveStrong Foundation says that, on an hourly basis, raking leaves burns about the same calories as bicycling.
Learn all about composting leaves and other yard debris at clarkcountycomposts.org.
Not trash
Recycling leaves back into nature, one way or another, is a great idea. Dumping them in neighborhood streets, where they clog storm drains, or bagging them up and sending them to landfills, are not.
In 2018, 10.5 million tons of leaves and other yard debris went into landfills, according to the U.S. Environmental Protection Agency. That’s not just a big waste of natural energy and material, it also generates methane, a dangerous greenhouse gas that contributes to climate change.
Don’t put leaves into the landfill stream. Instead, dispose of excess leaves in your regular yard-debris or organics cart. You can also drop off leaf loads for free, through the end of the year, at four recycling sites using coupons provided via a Vancouver-Clark County partnership. The four sites are H&H Wood Recyclers, McFarlane’s Bark, West Vancouver Materials Recovery Center and Triangle Resources in Camas.
Addresses, hours and more information can be found on the coupon. Coupons in Spanish, Russian and Vietnamese are available.
All the leaves you drop off at these sites will be turned into nutrient-rich, organic compost that’s available for purchase. Around 2,000 tons of leaves are disposed of every year through this program, according to Clark County Green Neighbors.
