Garden On, Vashon

It’s gold! Lying along the roadways! Littering our yards and gardens! Right on the ground, free for the taking!

I am, of course, talking about leaves.

The more I learn about using leaves in the garden, the more I want. When added to garden beds, leaf mould can double soil’s ability to hold water while cutting in half its need for fertilizer. You can grow seeds in it: you can feed your compost with it. If you mow leaves on your lawn, you will feed the soil, encourage microbial activity, build up a water reserve in the soil and thus help your lawn stay greener next summer.

More reasons for collecting and processing leaves:

• Shredded leaves make a good-looking mulch to protect your plantings over the winter.

• You’ll get the windfall of leaves OFF your plantings so they won’t be smothered.

• When you’re weeding in spring and have bucketfuls of compostable “greens”, you’ll already have a stockpile of “browns” at hand to make up a new compost pile.

So grab your rakes, your mower, and the biggest bags you can find. Let’s go harvest.

How considerate! Somebody at PSE had already windrowed these oak leaves: a few minutes of hand-scooping yielded 1 garbage bag and 3 grocery bags full, and that hardly made a dent in this row.

Processing leaves on a flat lawn or patio

First, find a motherlode. My neighbor was surprised but delighted when I knocked on her door and announced “I want to mow your lawn!” I told her what I really wanted were the leaves under her big maple tree standing solo in the grass.

“Go right ahead,” she said: “We can’t seem to get anybody to do it for pay anyway.” (Moral: they’ll never say No to somebody who wants to be paid in leaves…)

Leaves convey their benefits much faster if you shred them. Mostly made of carbon—as much carbon as cornstalks—they won’t decay quickly on their own. They need contact with soil and a little pre-chewing to work on your lawn, in your beds, and in your compost pile. And of all the tools that chew, a mower works great and I’m guessing you’ve got one.

When there’s nothing but leaves under a tree, the job is sooooo easy: I just rev’d up the mower and ran it over the carpet of leaves. You can pre-rake into windrows to concentrate the leaves before your mower, but don’t make them too high: I found that piles higher than 6″ made my engine sputter. 

The leaves reduce so low you’ll worry there’s nothing left, but a plastic rake with wide tines will coax most of this out of the grass and into those bags or boxes you brought along. I got seven garbage bags full of shredded leaves within 90 minutes: enough to cover a new 100′ perennial bed AND fill a 4′ square wire bin.

Should you decide to bag and bring those leaves home, another good site to run your mower over leaves is a smooth driveway or patio. The shreddings do blow sideways, but it’s easy to broom them up with a dust-pan—quite tidy!

Processing along the road: Be cautious

For mowing through leaves on rough grass—such as the roadside verge I worked this afternoon during a sunbreak in our week’s rain—it’s helpful to have a metal rake with thin tines that can “comb” the shreddings out of the grass. And I did pre-rake leaves off the slope down into windrows my mower could access.

Left: I've started to windrow the roadside maple leaves; Right, after mowing and raking for 90 minutes, eight bags full and one dead truck!

When working along the road, be cautious. First, alert oncoming drivers to your presence. If you can find an orange safety cone, put it on the road’s shoulder between oncoming traffic and you. Make eye-contact with drivers, or pause and stand as they come close. They might not see you anyway: with the sun so low these November afternoons, they might be squinting into the sun and not see you at all.

And use your EARS—that means, leave your noisy leaf-blower at home. Some poor Parks employee working a leaf-blower was hit by a car in Bellevue this week: probably couldn’t hear the approaching car for all the racket his tool was making.

Also, before mowing, sift through the leaves with your feet or your rake’s handle to find any bottles or breakables hiding under the leaves. 

And finally, one would THINK that turning on the emergency flashers would make a good alert system, but with the lights on for 90 minutes, my battery ran dead!  I was only saved from a LOONNNG walk home to hubbie and car #2 by a passing neighbor with jumper cables and the ability to read my “Please stop! Please stop!” mind.

Now you’ve got it, let’s make leaf compost

Rich in carbon, leaves are one of the classic “browns” of composting. Shredding will make them decay faster. Last year when I made my first leaf bin, my intention was to let the leaves sit and moulder for a year or two. But as it sat right next to my always-in-development compost piles, it was toooo easy to dip into the leaves for any “browns” my compost needed. This year, I’m making a second leaf bin just for the hungry compost.

Because they are so dry and carbon-rugged on their own, a pile of leaves needs a year or two to fully decompose. I saw this in my own bin: after the first year, the center had mouldered to a sweet brown duff with no distinquishable leaves, while the outside still showed layers of recognizable leaves. 

Apparently, wintered-over leaves are excellent for tomatoes if you till one-inch-worth into their soil next spring before planting out. A study by Dr. Abigail Maynard at the Connecticut Ag Research Station found that yields increased 25% using either winter-stockpiled leaves that were spring-tilled into the bed, or 2-year-old leaf compost. (Dr. Maynard did numerous studies on growing vegetables with leaf composts: the link is below and it’s fascinating reading if you’re into composting.*)

You can speed up decay by wetting the pile and by sprinkling on nitrogen-rich sources like urea or ammonium nitrate—or okara, that smelly tofu by-product if you dare! Enclose that mixture in a garbage bag and leave it for six months—a few holes poked in for air and drainage—and reports say you’ll have sweet, friable leaf mould by spring.

Why Bother? the Many Benefits of Leaf Mould

Here’s the hearsay: At my mother’s house last fall, I amended her tomato beds by jamming vine maple leaves and old compost into the stiff clay with a shovel. By summer, the soil was open and “wonderful to work.”

Now here’s the science: the university studies I found on the web that tell me how useful leaf compost can be. If you want to read these (they vary from 2-14 pages in pdf form), follow the links. The results of these studies found that: 

• additions of leaf mould can increase your soil’s ability to retain water by 50-250%. (depends on soil type, and also who you read…)*

• Yearly additions of leaf mould can, over specific times for specific crops, provide all the fertilizer your vegetables and flowers need. Increased yields up to 25% can be had by adding a 5-5-5 fertilizer. (Greens will probably need a little nitrogen boost from legume cover crops or blood meal).*

• Additions of leaf mould can double the organic content of your soil over the years.*

• A study at Purdue reassured Grounds-keeper Online readers that mowing even a thick 6″ carpet of leaves over grass would enhance, not deplete, the fertility of their lawns—even increasing soil microbial activity and helping retain water, all while costing 80% less than bagging and hauling away.**

*(Connecticut Ag Research Station, “Compost” study by Abigail Maynard)

** Mulching Tree Leaves: An Alternative to Disposal” from GroundsMaintenance online

So for a little time and exercise (and you want exercise, right?), you’ll provide tons of benefits to your plants, soil, and lawn. Free Gold. There for the taking. Islanders, to your Rakes!