PHILADELPHIA -- Fashionistas in the garden like those great big blooms with petals thick as petticoats, but there's another way to go: rock-garden plants.
Their flowers are small, subtle, and every bit as beautiful as their hefty peers, as Ann Rosenberg of Bryn Mawr, Pa., discovered around 1985. On a trip to England that year, she delighted in some small penstemons, which sparked an interest in other plants commonly used in rock gardens.
"They're so cute!" she says.
They're usually less than 4 inches tall, maybe as tall as 12 inches if you count things like dwarf conifers, another popular rock-garden feature. Their flowers can be very colorful and disproportionately large, and you can squeeze a lot of them into a small space, something all gardeners seem genetically wired to do.
Shaped like buns, mats and cushions, these tiny plants are tucked into crevices and fissures, where there may be little soil, their diminutive stature intended to show off the color, form, size and texture of the rocks.
That "small space" can be a container, a trough or a raised bed, a bonsai dish, antique sink, or perennial patch. Fill can be a mix of topsoil and sand, or gravel, or weathered rock fragments known as scree. The "garden" can even be a wall: Morris Arboretum in Philadelphia's Chestnut Hill, has a six-foot wall made of Wissahickon schist that's tufted with jewel-toned alpine plants.
Rosenberg doesn't have a rock garden per se; she uses home-grown rock-garden plants to create a dreamy woodland behind her house. There, clouds of soft-blue forget-me-nots and ultraviolet wildflowers known as bluets (or Quaker ladies) line the gently curved paths. They brighten a cloudy day like minuscule sparklers, set against the tart spring-green of everything else.
Rosenberg also grows primula and armeria, daphne, dianthus, gentian, and mini-hosta and mini-narcissus in there, and in rough troughs made by her husband, Dick.
Gentiana acaulis is a favorite. It's a kingfisher-blue gentian, 4 inches tall, an Alpine native with solitary trumpet-flowers measuring 2 1/2 inches long. Imagine a hillside dotted with these.
Which recalls this advice: Whatever form it takes, a rock garden should look natural, as if this craggy scene has been growing undisturbed for some time.
Pat Valentine puts it simply. "A rock garden consists of plants planted next to rocks, but it's not just that. There's an extreme art to it," he says. "You try to copy what's growing on the side of a mountain."
Valentine owns Valentine Gardens, a specialty nursery in Coatesville, Pa., that propagates and sells unusual plants for rock, water, sun and shade gardens. He's built a figure-eight rock garden in the sunny yard to show visitors how it's done, at least in this country. (There are many distinct rock-garden cultures around the world.)
But when asked to explain the attraction of these miniature landscapes of deep-rooted plants, Valentine's as mushy as Rosenberg.
"They're so cute," he says.
"Touring" this garden is nothing like a spin through a blizzard of perennials. We stand at the edge, bend over, look closely. We move six inches to the right, bend over, look closely. It takes nearly an hour to make our way around the figure eight, which is 22 feet long and 10 to 12 feet wide, with a pitcher's mound in the middle.
"It's a real neat facet of gardening," says Valentine, who's made a living in the nursery and landscape trade for 47 years. He bought this nursery with partner Patricia Schrieber in 2001.
The couple's rock garden is only 2 years old but already is a draw for tunneling mice, voles and ants. Today there's a break in the action, allowing us to safely inspect the funny habits of these curious plants.
They creep. They mound. They poke out of cracks and hug the ground. Valentine finds them quirky and romantic and says grandly that working with them can involve "major character development."
There's an alpine baby's breath, really just a green cushion with pinhead-buds. There are dwarf conifers and rugs of thyme and sedum inching around mounds of a moss phlox called 'Crackerjack' and 'Little Jock,' a frilly dianthus.
Everywhere, you see sempervivum or "hens and chicks." There's no mistaking those chubby leaves of pink or green and those distinctive cobweb hairdos. And get a load of the red or black tips. They resemble sharpened fingernails.
The "chicks" are the rosette-shaped offspring that grow in a ring around the "hen" or mother plant. As some indication that, even in a rock garden, the action is hot and heavy, the "chicks" naturally "fill the vacancies," as Valentine describes the holes left after the mothers flower and die.
He uses feather rock, lichen-covered limestone, jagged lava rock, granite street stone, and the occasional piece of quartz. Some were bought, but most were dug out of his yard or discarded by clients, friends or contractors. Size and shape vary, but none is a boulder.
"Look for natural stone," Valentine says, "and scale is very important."
Which recommends the rock-garden concept to urban gardeners and others without much space.
"These plants grow well in containers and troughs, which you can put at eye level in a condo on the porch or deck, and they'll work very well," says Bobby Ward of Raleigh, N.C., executive secretary of the North American Rock Garden Society. The society has 38 chapters in Canada and the U.S.
Ward acknowledges that rock gardens, regardless of size, may not appeal to everyone. "They're not garish. They're not big and bold," he says.
They require attention to detail, an artistic eye, and, sometimes, a tolerance for finicky habits. If you can manage all that, you'll be a goner for buns, mats, and cushions.
Soon you, too, will be saying, "They're so cute!"
* North American Rock Garden Society -- http://www.nargs.org/ -- and its Delaware Valley chapter, http://www.dvcnargs.org/.
* The Rock Garden Plant Primer by Christopher Grey-Wilson, Timber Press, $29.95.
* Creating and Planting Alpine Gardens by Rex Murfitt, B.B. Mackey Books of Wayne, $22.50. Available from http://www.mackeybooks.com/ or other sources.
* A Year in a Rock Garden: An Organic Gardening Guide by Ron Kushner, a master gardener and Pennsylvania-certified horticulturist, available for $19.95 from http://www.ronsorganicgarden.com/ or other sources.