Mulch With Dried Leaves

Spreading shredded leaves helps to control weed growth while providing soil with organic nutrients.

Spreading leaves

Shredded leaf mulch is efficient to apply and highly effective.

Photo courtesy of Yaicha Cowell-Sarofeen

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With more than forty years of experience redefining gardening's boundaries, author Will Bonsall shows how readers can eliminate the use of off-farm inputs like fertilizers, minerals, and animal manures by practicing a purely veganic, or plant-based, agriculture-not for strictly moral or philosophical reasons, but because it is more ecologically efficient and makes good business sense.

In Will Bonsall’s Essential Guide to Radical, Self-Reliant Gardening, (Chelsea Green Publishing, 2015) he offers readers in-depth information on growing, harvesting, and processing an incredibly diverse variety of food crops. The following excerpt is from Chapter 3, “Mulch.”

You can purchase this book from the MOTHER EARTH NEWS STORE: Will Bonsall’s Essential Guide to Radical Self-Reliant Gardening

For those who question the fertilizing power of tree leaves, I would share a couple of anecdotes. Although I have many acres of hardwood forest where I could collect my own leaves, I usually prefer to haul them from the town of Farmington, 8 miles (12.9 km) away. I’m doing the people of Farmington a favor by hauling theirs away (the town used to do it but no more), plus they’re already raked into piles, relatively free of twigs and branches. Of course I always ask the owner if I may take them, even though the response is predictably something like “What! Is the pope Catholic?” At one home on a shady side street, I asked the owner, an elderly woman with a charming Austrian accent, and she answered graciously, “No, I want them myself.” Intrigued, I asked wherefore, and she replied, “I need them for my garden.” Delighted, I probed further. She, having no known ideological views on the subject, relied exclusively on the maple leaves because they were what she had—the shade-free portion of her yard was wholly occupied by her garden, so there was little lawn to supply grass clippings, and she had no access to manure. She had no formal system for shredding or composting; she merely said: “I mull them over from time to time.” That had been her “system” for years, and the heavy-feeding cabbages and leeks I saw testified to her success. The huge pile of leaves in her yard was waiting to be converted into next year’s sauerkraut!

Second story: I once persuaded the Town of Farmington street commissioner that they should truck their curbside leaves up to my place rather than to the town dump. Yes, he hastened to agree, it made good sense for everyone. The first two truckloads landed in my leaf dump, and I congratulated myself that henceforth I would merely wait for the annual windfall. Next year they didn’t show up, so I asked the street commissioner, what gives? Well, it turns out that they need them at the landfill. Need them? I repeated dumbly. Ayuh, it seems they need them to add to the cleanings of the fairground horse stables. Ah, says I knowingly, it’s to balance the excess nitrogen in the manure. Weeell, not quite, he corrects me; it’s rather that all that sawdust bedding makes the piles cold, despite the pony doo-doo. What! They’re using “my” leaves to heat up horse-hockey so it will be well composted? And does it? "Yep," assured the commissioner with no irony intended, "works slick as shit."

Shredding Leaves

Most of the ways I use leaves require shredding, and that involves some kind of shredder. In my case I have an Amerind-MacKissick chipper/shredder designed to work as an attachment with my Gravely 12-horsepower walking tractor, but the chipper/shredder can be powered by any other PTO source or can be purchased with its own self-contained engine. For chipping brush the 12 hp is really needed to accomplish anything, but for shredding leaves a lighter power source might be quite adequate. An advantage of mounting this shredder on something is that it is easier to move about—on its own it’s cumbersome to move any distance.

My Gravely, by the way, is a magnificent machine, which is probably why Gravelys are no longer made. Because such walking tractors have several interchangeable attachments (mowers, snow blowers, tillers, and more), you don’t need to own several engines, all of which require maintenance. On the other hand that means that if the one tractor is out of order, you cannot do any of those jobs. Changing attachments is a rather minor nuisance and should not weigh very heavily against that option.

The safety grating on my chipper/shredder won’t allow anything less than 3⁄4 inch (1.9 cm) in size to pass through, so the product has a very uniform consistency, perfect for applying. I simply walk down the paths with a large rubber barrel full of shreds held on one shoulder and with my free hand create a blizzard of leaf confetti over the beds.

The crop plants are usually a few inches tall, and the shreds drift down and settle down nicely around the plants, making a tight and effective mulch with minimal effort. That’s why it is important that they be consistently fine—confetti-like: so that no clumps of whole leaves will smother the crop. Also, shredded leaves stay put in a breeze much better than whole leaves, especially once they’ve been wet and settle into a tight “felt.”

Another reason for shredding leaves is the twigs. Although I remove the larger branches for chipping separately, most leaves have a lot of fine twigs that are a nuisance to pick out, yet I don’t want them left whole. This is especially an issue with leaves collected in the forest or from lawns with big old trees (the ones with deepest roots and thus better trace-mineral content). When fed through the shredder they are reduced to harmless little chips that bother nothing, although you may need to pre-snap longer twigs so they don’t block the chute.

If I’m using partly wet leaves they will plug up the grate, but if I remove the grate they’ll come out too fast, only half shredded. Half shredded is okay as long as I can put them right back through again, giving me a product somewhat like the confetti, though not as uniform. For mulching paths and wider-spaced crops, and for making compost, this is quite satisfactory. (Remember, once the grate is removed, there’s nothing between you and the spinning hammer mills, so stand clear.)

I need to stockpile as much confetti as possible when they’re crispy and dry, and so I race to shred those as fast as they come in, and pack them into a large (8 × 10 × 4-foot, or 2.4 × 3.0 × 1.2 m) covered plank bin that holds roughly 2 tons (1.8 tonnes). If I have a real lot of confetti, I can pack it into feed bags and cover them with a tarp against rain and snow. I use lots of those banked up against the exterior door of my cellar for insulation during the winter.

A well-powered chipper/shredder is the best way to shred leaves, but it is not the only way. My father used to pile his leaves up by the garage door and run through the pile repeatedly with his push power mower, stirring it up between passes. Cousin Tom makes his into a long, very deep pile (3 feet, or 0.9 m) and wades through it repeatedly with his rototiller, re-gathering it as it spreads out. And of course, we all know the hands-down most efficient way of shredding leaves: You gather them all into a huge pile in the middle of the lawn and tell your kids and all the neighbor kids: “Stay out of this.” Within hours the pile will be reduced to molecules. (To accelerate the process you could hang a used car tire from an overhead limb.)

The problem with all these alternatives is the lack of consistency; some will be crushed to powder while some large pieces will remain. This isn’t a big problem for some uses (say, compost), but for mulching closely spaced crops, including grain, the crude shreds are more difficult to apply. For mulching more wide-spaced crops, like cabbage and tomatoes, and for paths, the cruder shreds produced by a lawn mower work well.

I often end up with more leaves than I can shred immediately. When I have run out of time I have also stored whole leaves loose in a hex-wire (aka chicken wire) enclosed leaf dump, which I cover with a well-weighted tarp. The leaves stay pretty dry until I can shred them the following spring or summer. During this time the bottom layer will get somewhat damp from wicking ground moisture. If I am short on confetti the following spring, sometimes I just spread the dampish leaves out on a tarp to re-dry for some hours and then shred them, although usually I just use the crude method, double-shredding without the grate in place.

Some degree of shredding is necessary for composting leaves, because whole leaves tend to form a soggy mat that will take forever to break down. In fact that was what got me into shredding in the first place: Because I could use only thin layers of whole leaves in the compost pile, I was always using much less than I wanted, in proportion to the hay and other stuff. Once shredded, leaves can be the major ingredient in my pile, quite compatible with my eco-efficiency obsession. Indeed, aside from leaves and brushwood, my composting of corn, sunflower, and amaranth stalks would be very difficult without first shredding them. By reducing the volume and exposing more surface of those materials, I greatly increase the rate of decay, plus the biological heat that renders a superior end product.


Reprinted with permission from Will Bonsall’s Essential Guide to Radical, Self-Reliant Gardening  by Will Bonsall and published by Chelsea Green Publishing, 2015. Buy this book from our store: Will Bonsall’s Essential Guide to Radical, Self-Reliant Gardening.