I’ve lived in Evanston, a Chicago suburb, for 43 years. I can confirm that for 43 years, most of the organic growth from Evanston’s soil—grass clippings, leaves, shrub prunings, tree branches—left the city limits. Almost none was returned to the soil. Yes, there was always the occasional composter or real gardener who kept that precious material on their property, supporting earth’s ability to renew life within our 7.8 square miles.
Today, in 2019, I would guess that the annual percentage of plant growth that remains within the city of Evanston is still in the single digits. Yes, we probably have a few more serious composters and Evanston is now certified as a wildlife habitat city. Yes, I believe the City is offering wood chips again. But it’s my educated guess as a retired professional gardener, that 90% of Evanston’s annual production of grass, leaves, shrubs, and trees—i.e., next year’s soil–still gets trucked outside the city limits.
At the very least this means that for 43 years we have interrupted nature’s cycle of replenishing the soils of Evanston. Add worsening soil erosion (hard rains, flooding, and humans’ increasing aversion to “dirt”), increased use of poisons (pesticides, herbicides), and decrease in biodiversity (including micro-organisms). That means we have soil that is less fertile, less capable of absorbing water, and possibly poisonous.
This means that one of the easiest and most impactful climate mitigation action–active carbon sequestration in our suburban Tree City–is reduced. And, speaking of climate action, did I mention the increased use of leaf blowers as an increasing contributor of greenhouse gas emissions within Evanston?
In 2004, as I neared the end of my gardening career (retired in 2007), the Evanston Roundtable published my letter about “leaving the leaves” (grass clippings, etc.) following a drought year. My letter seems surprisingly outdated in terms of its sense of climate mitigation urgency. Mostly I was concentrating on conservation of fossil fuels, not complete elimination. But the dichotomy expressed is still valid: We have numerous reasons to keep our leaves vs. one reason to throw them away every year. And now we understand—through scientific knowledge and direct experience—that there is urgency to do anything we can to (a) eliminate fossil fuel use, and (b) facilitate carbon sequestration on every piece of land.
On Oct. 31, 2019, the Chicago area had an extreme weather convergence: In Evanston we had 2-3” of heavy wet snow sticking to every surface imaginable, including every leaf and twig, followed by a hard frost (24 degrees), our first frost of the season. When the sun came up on Nov. 1, the frozen, wet leaves started dropping wholesale, leaving large pools of distinctive colors & textures on the ground—yellowed hackberry, butterscotch elm, blackened catalpa, giant compound Tree of Heaven leaves, crumpled brownish mulberry, golden-peach sweet gum, etc. This is a vision of the productive wealth of soil. Can we now see that it is riches worth keeping? riches that are free?
As we are asking in the political sphere these days, Which side are you on?* If Evanston wants a climate action badge, we need to keep our leaves.
*Which Side Are You On? is a song written in the 1930s during a coal miners’ strike by Florence Reece, wife of a coal union organizer (Harlan County, KY). Above all, it asks us to think clearly and to make a decision.
Here’s my reasons for leaving the leaves, this year and every year, now and in the spring.
Letter to Evanston Roundtable: Leave the Leaves
published March 31, 2004
A year ago, plants all over the Chicago area were dying. By mid-April, there were thousands of brown evergreens (dead), groundcovers killed to the roots (if not completely), and miscellaneous trees, shrubs, and perennials badly damaged or totally dead.
The direct cause was drought — a dry summer, fall, and winter of 2002 followed by late spring rains — too late for the survival of many plants. But if one looked closely, one might have noticed that gardens protected by autumn leaves had much less loss, if any.
As a professional gardener (for more than 20 years), I can say unequivocally that keeping our leaves is the single most important factor in maintaining a healthy, growing garden. And the least costly. But for some reason, as a society, we’ve decided to clean up the out-of-doors and to pay for it on a weekly basis. What gets forgotten is that we pay for it directly at least fourfold: we pay for an all-out fall clean-up, we pay for a spring clean-up, we pay for mulch to be brought in (to replace what we just paid to throw out), and then we pay increased water bills during dry periods because our unprotected soils and plants dry out so quickly. (And we in Evanston pay again with the sewer surcharge.) Sometimes, as in the spring of 2003, we pay to replace dead plants.
But there are other costs that we don’t pay any attention to because we don’t write checks. We pay with excessive noise pollution (from leaf blowers), we pay with air pollution (blowing dust and fumes from blowers, as well as unnecessary trucking of materials back and forth), and we pay with related health problems. All this trucking/blowing/mowing uses fossil fuels that are not replaceable.
Following is a list of reasons for leaving leaves, every one of which makes life more pleasant, is less labor intensive, and/or saves money. Leave the leaves in the fall, leave them in the spring, under shrubs, trees, and on perennial and groundcover beds. Yes, we need to get leaves off the lawns and off the walks; these can be spread underneath evergreens, behind shrubs, or piled up in an out-of-the-way area. But nature usually drops and blows just the right amount of leaves in perennial and groundcover beds, especially if over winter we leave the seedheads, ornamental grasses, etc., many of which provide food and cover for birds.
Leaving your leaves will….
- Create new soil, adding structure and nutrients, improving growing conditions — for free. This is especially important in east Evanston, where soils are light and sandy. The heavier soils of west Evanston will also benefit by loosening up the soils, encouraging worm and micro-organism action. Soils need “fiber”; plants can’t live just on “vitamins” (fertilizers).
- Protect existing soil from wind erosion. Our soils took 10,000 years to accumulate; should we squander them so lightly?
- Hold moisture in the soil; plants will need less water, less frequently.
- Protect plants against extreme weather (cold or heat, both of which can be drying). Some plants need protection against cold temperatures.
- Give you and your neighbors peace and quiet by decreased use of leaf blowers.
- Keep our air cleaner — less fumes, less stirred-up dust.
- Conserve fossil fuel by less frequent use of leafblowers and trucking of materials back and forth.
- Eliminate much of the time/cost of bagging up leaves.
- Protect the habitat of the small creatures — worms, insects, micro-organisms — that create ideal soil conditions for healthy plants. Healthy plants are more disease- and pest-resistant.
- Show us the beauty of natural processes. How awe-inspiring to see little green tips breaking through the brown leaves this time of year. How fine this cycle of life.
What are the reasons to throw leaves away?
I would ask,
what’s “neat” about air pollution?
what’s “neat” about unhealthy plants?
what’s “neat” about trees dropping leaves in the middle of summer for lack of moisture?
what’s “neat” about noise pollution (not to mention the health of the workers who use these noisy machines, almost universally without ear protection)?
What’s “neat” about squandering our resources — our soil, fossil fuels, water, and air?
Evanston, IL 60202
NOTE: A longer version of this letter was published in 2005 as an article in HortIdeas, an on-line horticulture & farming newsletter. In the Sept/Oct 2005 issue of American Gardener (magazine of the American Horticultural Society), my HortIdeas article was summarized in a sidebar.