Rock gardening usually starts small, in an area about the size of the bottom of an aquarium -- and just as gravelly -- and then takes on a life of its own. Like a weakness for paperweights or baseball cards, it becomes something of a passion.
Rock gardens and all the diminutive but tough plants that thrive in them are evocative of hard, lonely landscapes in the mountains or the desert, and they can get a grip on your imagination in the middle of a lush temperate-zone garden.
The plants that thrive in what would otherwise be considered difficult conditions -- lean soil and not much water -- are widely available. They're an interesting bunch, the little dianthus, columbines, cacti and succulents, and dwarf conifers that have such a hard time finding their places among the strapping lilies and peonies in a perennial border.
Instead of trying to work them into a grand garden design, make a place for these small plants and set them apart from the crowd: They will shine for you. The rocks, and they can be any old rocks or fine specimens bought for the purpose, provide the rugged atmosphere. They also absorb the sun's heat, and help create the conditions these plants like.
Although the most spectacular rock gardens are enormous and elaborate affairs with monstrous boulders and even larger budgets, you don't need a fortune or access to a quarry to make your own. A simple rock garden can be put together with half a dozen plants in a terra-cotta dish or in a stone or hypertufa trough.
Trough gardening is perhaps the easiest and most popular form of rock gardening, and it's a great way to get started. The weathered appearance of these faux (or real) stone troughs, or sinks, suits the character of the scrappy plants you'll grow in them.
Troughs and dish gardens fit easily into gardens of all kinds. Some gardeners place them at the front of flower beds, raising them up on rocks so you don't have to get down on your knees to enjoy them. Shallow dish gardens in terra-cotta saucers can march up the front stairs or fill in an awkward empty corner. Traditional English sink gardens are frequently arranged in sheltered courtyards, with troughs of various sizes displaying a quirky collection of plants.
Botanic gardens offer some of the most spectacular examples of the diversity of rock-garden plants and styles. They're beyond the ambitions of backyard gardeners, but these big rock gardens provide plenty of inspiration.
At Powell Gardens, just outside Kansas City, Mo., a limestone wall about 5 feet tall and 600 feet long, known as the gardens' "living wall," is planted with more than 250 species of fascinating hardy plants that grow in the cracks between the stones. Silvery santolina billows out from the rocks at knee height; sunny yellow primroses tumble over the edges of the wall; colorful salvias flash against the stones through the bright, hot summer.
At the Denver Botanic Garden, the rock garden is even grander, with 4,000 plants from around the world. The garden is put together with granite boulders, chunky limestone, sandstone and porous tufa. Wildflowers, tiny bulbs, phlox, ice plant, penstemon, campanula, small conifers, yuccas and agaves grow up rocky slopes and in crevices.
It's a new gardening world, and what could be better than that? Getting to know these rock garden plants takes time; even the names seem strange at first. You'll get to know a new circle of gardeners, too -- once you show an interest, they'll be coming out from under the rocks.
The North American Rock Garden Society (www.nargs.org)
Rock Garden Design and Construction, written by NARGS members and edited by Jane McGary (Timber Press, $30)
Creating and Planting Garden Troughs by Joyce Fingerut and Rex Murfitt (B.B. Mackey, $21)
Small perennials and bulbs, dwarf conifers and many other plants suitable for rock gardening can be found at most garden shops.