Grass and weeds are beginning to appeaar in a stone field.

Grass and weeds are beginning to appeaar in a stone field.

One of our local landscape supply store sells bulk materials, and they have a unique display.

Between the road and their parking area there is a steep bank. As you drive past, you cannot help but see about six stripes of different colors and textures of mulch and gravel available for bulk purchase. It is a “rainbow” with 8-foot-wide stripes of black, brown and red for the dyed mulch colors and burgundy, gray and white-ish for the gravel and river rock.

Two of our customers have recently been smitten. “That difficult-to-maintain section in the back yard would be so much easier to maintain if we just spread a load of that beautiful river rock . . . wouldn’t it? Rock is permanent and inhospitable to weeds. And if we just copy the landfill and cover the ground with a sheet of plastic first . . . we would eliminate our maintenance costs. And mulch fades and disintegrates, so the rock will stay that color permanently, right?”

Not so fast. Have you ever kayaked down the Delaware River before? (Some landscape river rock is actually labeled Delaware river rock). If the water is low, shoals of river rock appear. If the water stays low for a while, the shoals sprout all kinds of grasses and trees. So weeds have no problems growing in river rock in its natural environment. Why? Do weeds grow in the rock? Of course not, but they grow in the silt that accumulates between the rocks.

If you visit Hickory Run State Park’s boulder field, you will find a landscape where vehicle-sized pieces of gravel cover an area larger than your entire neighborhood. You will also find signs fretting that this ancient geological wonder is shrinking due to the forest invading its perimeter.

Maybe the landscapers who turn backyards into stonescapes should put up the same kind of signs. WARNING: Even with endless weeding and spraying chemicals, this mini-boulder field will always be collecting leaves, dust and seeds. Sooner rather than later, the forest will win.

Stone cannot be considered a permanent solution to a landscape problem, and in fact, brings about its own problems. If you could zoom in to the giant stone patch in the photo, you would see that even though it is only four months old, the edges are already inundated with grass, and throughout the bed, other “volunteers” are beginning to appear.

Recently, we visited a new customer’s house. The house and landscape were six years old.

“Along the edge of the bed, there was a river rock stripe,” she said.

“Where? Here?” I said, digging my boot into the lawn that was pushing into the 150-foot-long mulch bed.

“Yes,” she said. “It looked nice when we could see it.”

Joshua Arp is an ISA-certified municipal specialist, Clarks Summit’s municipal arborist and an operator of an organic lawn and landscape maintenance business. Reach him at

Recommended for you