Rocks in your head

Get to Know Your Stone

When you’re scouting for landscape rock, visit local stone yards (look under “Stone-Natural” in the Yellow Pages). You’ll quickly learn that “a rock is a rock is a rock” just isn’t true; the array of choices is mind-boggling. While your decision will be guided by your home’s look and the stone’s purpose, you’ll also want to ask these questions.

Where was the stone quarried and how far has it been shipped? Fossil fuels are used to quarry, mill, and ship stone—and with a material as heavy as stone, that’s no small concern. The closer the stone is to home, the better.

What is the quarry’s track record on reclamation? Quarrying is permitted only after a reclamation plan has been approved. To reclaim the land, any leftover scraps are pushed back into the ­­­­hole, followed by dirt removed from the next hole. Topsoil and seed complete the job. The end result may be a change to the terrain, but there should be no gaping holes or barren patches.

Was this gravel or rock mulch mined from a riverbed or elsewhere, or crushed to this size? By choosing crushed rock, you’re probably using a byproduct from a quarrying operation.

How porous is the rock? In some applications this doesn’t matter, but for a wall where freezing and thawing could cause damage, you’ll want to know. Lightweight volcanic stones and limestones are more porous than most.

Is it an acidic or basic rock? Limestone may make a water garden too alkaline, and it also can be degraded by acid rain.

How big must an ornamental boulder be? For the backyard of a modest neighborhood house, a half-ton boulder might fit nicely; on the grounds of a ranch, a ten-ton boulder would be suitable. Plan on burying at least a third of the boulder, or bury it up to the line that the boulder was buried to in its natural setting.

Will this stone look right in my yard? Many landscape designers prefer to work with native stones that fit the region’s cultural typography. An outcropping of red sandstone in the “Granite State” of New Hampshire or a slate patio in the Southwest might look a bit odd.