For a Growing Garden
What’s the secret to preventing weeds from sprouting? A 2-inch-deep topdressing, applied once the ground thaws, will do the trick. By selecting a mulch that suits your plants and site conditions, you’ll get even more benefits, such as healthier soil and less erosion.
Gravel
Stone absorbs more heat than organic material, making gravel a death sentence for some plants and a haven for others. Reserve this option for succulent-filled or cold-climate gardens.
Pro Tip: Jenn, the This Old House landscape contractor, points out that gravel is ideal “in high traffic areas, you know, like parking lots and stuff where you just see so much foot traffic, or in erosion situations.” She adds, “You have to use plants that are drought tolerant ’cause this will heat up the ground.”
Cocoa Hulls
These shells are filled with nutrients and maintain an attractive brown hue that darkens with age. They have a tendency to grow a harmless mold in humid climes. Warning: Like chocolate, cocoa hulls are toxic to dogs.
Shredded Bark
The stringy texture makes it less prone to being washed down slopes, and its coarseness keeps it from breaking down too quickly. Carbon-rich bark is a good choice around shrubs and trees but less so for perennials.
Pro Tip: Jenn, a This Old House landscape expert, cautions against dyed bark mulches: “They use dyes in it. And so dyes have chemicals in it, but they do it to have the color last, which I like to stay away from.” She explains that the color preservative “locks in the color and the color lasts longer. But then that’s also going to leach into your soil.”
Compost
This black gold doesn’t prevent weeds as well as woody mulches can, but it’s excellent for building up nutrients and repairing soil. Spread a generous layer over your flower beds and vegetable patch.
When using compost to tackle weedy areas, apply it thicker than you might expect. In compact garden beds with a lot of bare spots and weeds popping through, first remove the weeds, then spread about 4 to 6 inches of compost to make sure they don’t come back. In contrast, compost and grass clippings on established beds may be spread in a thinner 1- to 2-inch layer.
Wood Chips
You can’t beat the price of wood chips, which many tree companies and townships give away for free. Chips break down slowly and are best used around shrubs and trees. One drawback: They turn gray with age.
Pro Tip: Linda Chalker-Scott, director of the Sustainable Community Landscapes Program at the University of Washington’s Center for Urban Horticulture, favors arborist’s tree trimmings—chopped branches and leaves—for many gardening jobs because they’re inexpensive, readily available, and free of weed seeds. For converting a large, weedy area to a garden bed, she recommends mowing weeds to the ground, then covering the stubble with 8 to 10 inches of wood chips.
This Old House executive producer Russ Morash is a fan of homemade wood chip mulch spread thick: “Wait a year, and you’ll have rich forest soil.” A layer spread 3 or 4 inches deep around perennials or trees—starting 6 inches from the trunk—helps retain moisture, prevents erosion, reduces weeds, and nourishes microorganisms in the soil.
