For a free and easy mulch, use twigs
By Barbara Damrosch,
No matter how tidy you were about fall cleanup, the yard somehow manages to seem messy by spring. During the winter, stray leaves are blown into corners, and tree branches break, fall, and litter lawns and terraces. On a sunny day, as you get ready to tackle their removal, it’s a good time to think about tree debris in general, a greatly undervalued resource for the garden.
It may seem obvious, but a plant has its own program for feeding and mulching itself. What it casts off — dead leaves, stems, flowers — breaks down to replenish the soil at its feet. Hence the logic of mulching lawn mowers, which chew up clippings so they can feed the grass. Or the practice of raking autumn leaves into shrub and tree borders as a mulch.
But until recently, nobody paid much attention to twigs and brush. Branches too small to use for lumber or firewood are considered a nuisance to be burned, hauled away or chipped. And yet they’re the most fertile parts of the tree. The closer you get to the end of the branch, the more nutrients it contains.
Enter “ramial chipped wood,” which is just another name for chipped branches with a diameter of less than about three inches. A study done at Quebec’s Laval University in 1998 showed how the chips could be used to add long-lasting humus to grass-based soils. Organic orchardist Michael Phillips, author of the recent book “The Holistic Orchard,” has popularized their use as a mulch under fruit trees, to stimulate just the right fungal action and promote tree health. And mulching trees is easy for a home tree grower to do.
It matters what kind of branches you use. Evergreen branches produce compounds called polyphenolic inhibitors that keep competing plants from growing, and therefore should be used to mulch only the trees that produced them. Trees that lose their leaves in winter are much kinder to plant diversity. The best are ones such as alders and shrubby willows that are mostly small branches anyway and are frequently being cleared out to make room for other species.
The only thing I don’t like about wood chips is the chipper, a noisy, loud, smelly dragon of a tool. Those who share this dislike develop an eye for piles of chopped brush assembled by someone else. Most chip-makers are delighted to have you haul this byproduct away. Get the word out in the neighborhood that you’d like some.
Meanwhile, try breaking up twiggy material while you’re collecting it, remembering that the small stuff that snaps easily is the best. You’ll want to prune your fruit trees, too, before the buds open, so you might do some hand-chipping with the pruners and loppers since you’ve got them in your hands anyway. Then scatter them underneath the tree, as is its due.
Damrosch is a freelance writer and the author of “The Garden Primer.”