There are many styles of rock gardening. Europeans were the first to develop rock gardening as a way to mimic the Alps and other European mountain ranges and plant them with alpine plants, and this style of rock gardening remains extremely popular here and across “the Pond.” But rock gardening has evolved and reflects an expanded interest in small growing plants, many of which are not of alpine origin.
Rock Gardening in Arid Climates
Rock gardening is my favorite style of gardening, and the front yard of my Santa Fe home is planted as an expansive rock garden with a wide variety of xeric plants, large and small. Having been a gardener in the Rocky Mountains for most of my life, rocks and plants are a natural combination that I see all around me. I have adapted my style of rock gardening to reflect a xeric palette of plants best suited to the searing high elevation sun and dry growing conditions here in New Mexico. That, and I can’t afford the water needed to keep alpines happy.
The Importance of Rock
The rocks in rock gardens are just as important as the plants. For a more natural look, I think it is important to use a single type of rock as the foundation of a rock garden. And these rocks should be used in conjunction with soil berms (small hills) to give the rock garden topography that simulates a mountain and valley environment. In dry climates I always recommend sloping the rocks back into the slope so to facilitate water flowing into the berm. In moister climates, rocks should be arranged to shed water away from the berm.
A Well Drained Soil Mix
It is of vital importance to create a fast draining soil mix to build your berms with because many rock garden plants need excellent drainage. Especially in winter when a soil that is too moisture retentive can cause root rot. I like a mix of half coarse sand/crushed gravel with a good garden loam amended with some compost and rock dust (a trace mineral-rich blend like Planters II). Then I mulch with 1 to 2” thick layer of crushed (angular) 3/8” diameter gravel.
Rock Garden Plants
Over the years, I have developed a palette of small growing perennials, cold hardy succulents (native and South African) and cacti as a basis for the xeric rock garden.
Some of my favorites include:
Agave toumeyana ‘Bella” - a cold hardy, miniature century plant
Aloinopsis ‘Psychedelic’ (and other South African succulents) – extravagant flowers and incredible, other worldly succulent foliage
Aquilegia flabellata ‘Nana’ – a tiny blue flowered Columbine
Arenaria sp. Wallowa Mountains – a deep green xeric moss look alike
Delosperma ‘Gold Nugget’ – a sub-alpine Iceplant for north facing crevices
Dianthus ‘Nyewood Cream’ – incredibly fragrant
Erigeron scopulinus – a very rare native fleabane with cheerful white daisy flowers and tiny bright green leaves
Geranium dalmaticum – fantastic miniature perennial geranium
Penstemon pinifolius ‘Compactum’ – brilliant scarlet flowers over evergreen foliage that resembles tiny pine needles
Penstemon virens – small and colorful Beardtongue
Phlox kelseyi ‘Lemhi Purple’ – a stunning small grower with fragrant blue and dark blue flowers
Thymus neceffii – fantastic foliage and flowers
Veronica bombycina – superb nearly white foliage and bright blue spring flowers
There as so many great rock garden plant species, but these are really good, easy-to-grow plants to get started in this fascinating style of gardening.
Text and Photos by David Salman