What to do with your leaves, and on my devotion to leafmold

[This is my October column for the Takoma and Silver Spring Voice newspaper.  I'd love your feedback!]

Gardeners want to know: Do I really have to remove leaves from my lawn? And the answer is that a few are fine but a thick coating of leaves will smother turfgrass over the winter.

Next question: Can I leave them in my flower beds and borders? On that one opinions vary, and some sources even recommend raking leaves into the beds for the winter. But like most gardening advice, it depends – in this case on their size and shape, and how many you have. An impenetrable mat of leaves, especially from oaks, can smother groundcovers and keep rainwater from penetrating into the soil, so my own practice is to wait til all the leaves are down in late fall, then lightly rake the easy-to-get majority of them, being careful not to yank the groundcovers out of the soil. I hand-remove the remaining leaves during spring clean-up.

How to gather your leaves

Sometimes it’s the simplest of gardening chores that never get explained, and I’m reminded of this when I see people raking leaves a great distance – surely the hardest way to get them from one place to another. The most efficient way to move and gather leaves is to start uphill and rake down, enlisting gravity as your helper. Rake the leaves onto a large sheet or tarp and carry or drag them to their destination. (Personally, I find fabric more supple, and it takes up less space in the garage when not in use.) Raking the shortest distance possible is the idea.

An alternative to raking leaves on your lawn is to simply mow them. You can remove your grass catcher and just let the chopped-up leaves stay on your lawn as organic matter, a winter mulch that’ll improve the soil and attract earthworms. Or you can mow with the bag attached, then turn the chopped-up leaves into leafmold mulch or compost – more on those options below.

In the City of Takoma Park, most residents haul their leaves to the curb for the city’s leaf vacuum pick-up, after which the leaves are chopped and aged a few months and made available to everyone, regardless of residence, as free leafmold.

All about leafmold

Rumors about Takoma’s leafmold abound but don’t stand up well to fact-checking. Turns out it’s not acidic, an assumption that’s often made because so many of our trees are oaks. City Gardener Mike Welsh has tested the stuff and found it to be somewhat alkaline, which he offsets in his own garden by spreading Hollytone every third year around acid-lovers like azaleas.

Another rumor is that city mulch is filled with weeds, but in my 20+ years using it, I’ve never found that to be a problem. It does contain little bits of trash, both paper and plastic, and that are unsightly and have to be removed. So it’s not perfect like store-bought products, and some people would rather pay than have to remove bits of trash.

Now what’s leafmold good for? Because it’s not terribly rich in nutrients, it’s not really a fertilizer but as a soil amendment or additive it can’t be beat, especially for the price. It does everything that organic matter does for soil – increase its ability to both hold water and to drain it (it’s a miracle!), reduce compaction, and feed microorganisms and earthworms, thereby increasing their population in your soil. If your soil is clayey, just mix leafmold into the top 6-12 inches to loosen it up. So leafmold makes for healthier soil – the very foundation of organic gardening.

As a mulch (a top dressing over the soil) leafmold is my absolute favorite and the only mulch I’ve ever used. It does everything mulches are supposed to do – suppress weeds, moderate soil moisture, retain moisture, prevent mud splatter on plant and hard surfaces (like your house), add some nutrients to the soil, enable it to better use nutrients in the soil, increase the populations of earthworm and beneficial soil microbes, and make beds and borders look well kept – like gardens. That’s a lot.

Making your own leafmold

Now if you prefer to make your own leafmold, or live where there is no curbside leaf-vacuuming, here’s how it’s done. The lazyman’s method – my own – is to pile them up and let them sit for a year or two. But unless you regularly turn and water the pile, time alone won’t produce a nice uniform product; there will be some whole leaves at the bottom of that pile. Chopping them first gives the best result, whether by mowing over them with the grasscatcher attached, or running the leaves through a shredder/chipper. I once tried a cheapie shredder/chipper that used a Weedwacker-type plastic filament. Trouble was, every little acorn or twig broke the filament, which had to be replaced, and the process was so tedious I gave the shredder away. Anyway, I hated using a noisy, energy-guzzling machine to shred leaves – kinda contrary to the whole sustainability thing.

Watering the leaves as you add them to the pile will speed up the decomposition process, as will adding a source of nitrogen (grass clippings, or lawn fertilizer) and turning the pile occasionally.

Composting Leaves

Another source of confusion is between mulch and compost. Organic mulches like leafmold are only partially decomposed, while compost products are fully decomposed. Compost is a terrific growing medium, which means that as a mulch on top of the soil, seeds dropped on it by the birds or the breeze happily germinate in it, something they’re unlikely to do in mulch. Plus, compost looks like bare dirt, so it doesn’t provide that finished look that mulch gives a garden.

But if compost is what you want, leaves can be used as one of the two main ingredients in a nutritionally complete compost, the other being a source of nitrogen, like grass clippings. One compost system that works well is a rotating compost bin, but because all the ingredients have to be put in the bin at once, you’ll need another space to put the next batch of materials. Or if you’re using the classic square compost bins, you’ll need several of them in order to move the ingredients from bin to bin as you turn them regularly. Sadly, the single-bin systems I see in so many yards just don’t work. In fact, if kitchen scraps are your main ingredient, a worm composting bin that fits neatly in a closet or the basement is usually a better idea. (If kitchen scraps are composted outdoors, use a closed bin to keep out the larger, unwanted critters.)

What NOT to do with your leaves

- Send them to the landfill. Yard waste makes up between 5 and 30 percent of municipal landfills, depending on the location and season, despite the fact that it’s all recyclable organic matter! It’s heartening to see more and more jurisdictions recognizing the lunacy of sending organic matter to landfills and banning that practice in favor of recycling it into compost or mulch.

- Collect them using a blower. The gas-powered ones pollute and (duh) use gas, and there are no electric ones on the market with enough power to do the job. Plus, no matter how they’re powered, they kick up particulates containing mold, pesticides, dried animal waste and plain old dust. And then there’s the obnoxious, unneighborly high-pitched sound of the things! No surprise that they’re being banned in more and more communities across the country. The Noise Pollution Clearinghouse calls the leaf blower an "absurdly inefficient contraption as a replacement for leaf rake and patio broom" – sounds about right to me.

Photo by Frotzed via Flickr.