With around 350 members, the Rocky Mountain Chapter of the North American Rock Garden Society is one of the largest in the organization. Even so, rock gardens are fairly uncommon on the Front Range. This is a shame, because no other garden style is better suited to our unique conditions of weather, climate and geography.
For starters, there are aesthetic considerations. Some of my neighbors were lucky enough to discover huge sandstone slabs when their houses were built. These grace landscapes up and down the block. While gardeners on the plains of Colorado don’t generally turn up stones like these, when we add rocks to our gardens, we bring a bit of the mountains out onto the plains.
Rocks also make great companions for plants. It’s one of those yin-yang things, permanence versus ephemeral.
There are practical justifications for using rocks in gardens, as well. When a plant is tucked next to a rock, it is sheltered from wind and sun (depending on compass orientation) and temperature fluctuations at all seasons.
A rock provides nearby plants with extra water that collects at its base, and evaporation is slowed by its bulk. Savvy gardeners take advantage of this rock phenomenon to grow marginally hardy plants like agaves and red yuccas that are rated for one or two climate zones warmer than our own.
But when it comes to rock gardens, rocks are only one part of the equation. Of greater importance is plant selection. The rock gardener’s stock-in-trade is tough plants from harsh environments, places so forbidding that few people make their homes there. These plants include alpines from high in the mountains plus cushion plants and tufts from cold deserts and steppes. In either case, scratching out a living can be a challenge.
In response to desiccating winds, relentless and searing sunlight, arctic winter cold and a short growing season, plants in such environments evolved short and compact. And they don’t need pampering.
Nor do most of them actually require rock for success. Many traditional rock garden plants like moss phlox, aubrieta, hens and chicks, teucrium and thyme are also ideal for growing in containers, for planting in or cascading over rock walls, and for edging walks, beds and borders. Those with spreading or carpeting habits make nearly indestructible groundcovers or fillers between paving stones.
A new marketing pitch to promote rock garden plants, called Rock Stars, is a solid introduction to every facet of rock gardening (although I could not get the search to work at rockstarplants ). Look for the Rock Star designation on labels at local garden centers.
Also helpful is the rock garden society’s website at .
For a huge selection of rock- garden plants for every garden situation, visit the society’s Rocky Mountain Chapter plant sale, 9 a.m.-2 p.m. April 26 in Mitchell Hall at the Denver Botanic Gardens, 1005 York St., Denver. Experts will be on hand to help you choose plants.
Marcia Tatroe is a garden writer and lecturer. Her most recent book is “Cutting Edge Gardening in the Intermountain West,” ($29.95, Johnson Books). E-mail her at rltaurora@aol.com.
