By Charles Kidder
If you look at the accompanying photograph you’ll see a garden with a lot of rocks. But is it a “rock garden”? According to the purists, no.
Before I say too much about this “garden with rocks,” a few caveats. Most important, gardens should please the gardener, not a garden columnist or other arbiters of taste. Some anonymous gardener put considerable work into the creation you see here and should be applauded for it. And by the way, don’t be looking for this garden in western Albemarle County. It’s a couple of hundred miles away. I just have to hope that one of our readers isn’t saying, “Hey, isn’t that Uncle Bob’s garden?!”
If you’re seeking the gospel of rock gardening, one of the better places to look is the North American Rock Garden Society. NARGS consists of some 2,300 garden enthusiasts, all interested in rock gardening, but to widely varying degrees. Members are concentrated in North America but also hail from all the inhabited continents. Membership in the national group allows you to attend the annual meeting—this year it’s in Santa Fe in August—and to receive the society’s quarterly. You may also choose to join one of approximately three dozen local chapters. For us, the closest chapters are the Potomac Valley in the D.C. area, and the Piedmont in Raleigh.
According to a NARGS manifesto, “gardens in which rocks and plants appropriate to them are the chief landscape elements are called rock gardens.” (Kind of clumsy wording, but you get the idea.) They go on to say that if the plants are from either high altitude or sub-arctic environments, it would be considered an alpine garden. Such plants are not likely to do well around here, however. To have a “true” rock garden, the part about “plants appropriate to them” is most telling. Rock gardens were originally designed to mimic rocky summits in the Alps, with teeny plants clinging to life in cracks between the rocks. Forsythias aren’t going to cut it in your rock garden.
Plants are the fun part of gardening to most of us, but what about the possibly trickier part of The Rocks? And before you even decide about the rocks, what about the site? A slope is preferable since it mimics the conditions found on a mountain top, but if you’re working on level ground, consider bringing in sufficient topsoil to create a berm. As for the rocks, it might be tempting to use existing rocks on your property, but this really depends on what you’ve been dealt. A natural rock outcropping would make a good starting point for your garden, but only if you can find other rocks that are reasonably similar in appearance to add to it.
If you look at the accompanying picture again, you can find many reasons why those rocks don’t really work in that garden. First, they’re too light in color; they really jump out at you, rather than blending harmoniously with the plants. Secondly, rather than the angular chunks you see here, the layered structure of a sedimentary rock such as sandstone is generally easier to work with from a design standpoint, as well as for the mechanics of placing the rocks in the garden.
As for placement, there’s a saying in the rock business: Bury your Money. Even though you’ve paid XX dollars for a really nice rock, it’s going to look much more natural if about half of it is under the ground. Again, as you can see in the picture, those rocks just look like they were plopped on top of the ground. Which I’m sure was the case.
If you’re buying rocks, you’ll probably run into the distinction between rock and stone. At least from a landscaping perspective—rather than a geological one—rocks are typically cut from a quarry and tend to have sharp edges or even obvious drill marks. Stones, especially fieldstone, are objects that you might actually encounter when walking through a field. The edges typically have been worn down to some degree of smoothness, and they may have attractive moss or lichens growing on them. But using pea gravel, cobbles, boulders or other rounded rocks won’t look right unless you are trying to create the effect of a dry streambed. Why? Rocks that are worn smooth and rounded by the action of water wouldn’t be found on the dry mountain top you’re trying to recreate.
What about the material between and under your fancy new rocks? Rather than covering the spaces between them with an organic mulch, it will look more natural with a top-dressing of sharp gravel or rock fragments. Most rock garden plants prefer good drainage, so it’s best to also incorporate gravel into your soil.
And take all this advice on rock gardens with a grain of (rock) salt. Although some rock gardeners could be accused of horticultural snobbery, most are idiosyncratic types that are accepting of a wide range of garden styles. You have to laugh at a group that refers to some of its less successful efforts as “almond pudding,” “dog’s grave,” or “peanut brittle.”
