Although the British have been attributed with the popularity of the alpine rock garden, its origins are in the Swiss Alps. The Brits vacationed there in the early 1900s and brought back the low-growing plants to use at home.
I can’t think of two completely opposite climates for growing the same plants! The UK is damp and cloudy, and the Alps are wind-blown and sunny, but it was the rugged outcrops of the Alps that were attractive.
Alpine plants are subjected to high winds, bright sun, little water and few nutrients. They grow in pockets created by boulders, cracks in those boulders or in the path of snowmelt. They thrive on rocky slopes on very little! Because of the wind, they hug the ground, creating colorful mounds and carpeting. Their durability and low maintenance make them useful on slopes to help prevent soil erosion, but they are also effective in borders and rock walls.
Adding Alpine plants to a rock garden
If you are fortunate enough to have a rocky slope, observe what grows there already and how it grows. Alpine plants tend to be scattered, not clustered, like in the flowerbeds around your house. Each plant is visible, standing out on its own. You can add alpine plants to your slope in pockets above the boulders. They do not need highly improved soil. Sandy soil with a bit of compost works well. No peat moss for water retention! The soil does not need to be deep, but it must have good drainage. Remember, these plants thrive in shallow soils and snowmelt!
If two boulders are close together, create a planting pocket between them. Some rocks have huge indentations, which can be also filled with soil and a plant. This is how Alpine plants grow in their native setting. They find where water collects and set down roots.
Creating a rocky slope to scale for an Alpine rock garden
You can create a rocky slope, and you won’t need much room. It can be in a corner or at the edge of your yard. Bring in soil and rocks that are in scale with your space. If you have 1/10th of an acre, you do not want 1000-pound boulders! Small space equals small rocks.
Scatter your boulders on the soil you have built up. You want this to look natural, like the rocks tumbled down a hill and landed in your yard. Do not make a symmetrical pattern, and do not place them equally distant from each other. Make planting pockets in places where water collects – above the rocks and where there is run-off. Even if you have a small urban yard, you can do this. A natural looking rock garden makes a beautiful entryway!
Rocks should be native to keep with the natural look. In the city, you can be more creative with your rock choices, since there probably (and sadly) is not much to use as a point of reference. In any setting, you can showcase rocks mostly or plants mostly. A water feature, such as a small pond, a fountain or a trickling brook, adds to the natural feel.
Stone retaining walls for rock gardens
Stone retaining walls are a wonderful place for alpine plants to grow. As the wall is built, plan for spaces between rocks to put a bit of soil and a plant. The top of the wall can hold more plants that will cascade down the front. Remember, alpine plants are low-lying ground huggers. They will soften a stone wall.
Rock garden flower borders imitate the big version. Scatter different size rocks as though they tumbled into your yard, and plant around them. This is an attractive entry way or a simple way to define an outdoor sitting area. You can also create a berm for definition. Again, add rocks that look natural and plant around them.
Rock gardens are low-maintenance
Once a rock garden is in place, it is very low maintenance. These plants require little water, so a rock garden may be a good choice if you have watering restrictions. The rocks act as mulch, and as the ground covers spread, they hold moisture in, too. Rock gardens do not need much fertilizer, either. A little hand weeding will keep your original design intact.
For the busy lifestyles of the 21st century, the rock garden can be a good solution as a time saver coupled with food for the soul.