What is an Alpine plant?
Will Ingwerson, expert on all things for the rockery, said that this a “no more than a loose and very general term to describe plants suitable for growing in the simulated alpine conditions which we try to provide in our gardens. The plants need not come from the Alps, but may come from any mountainous region in the world. In fact, they may come from any temperate climate, as long as they perform under alpine conditions.”
An old Maine farmer was once quoted by someone from away that “my best crop has always been the rocks I harvest from my fields.” He was perhaps exaggerating to make his point but, we think, not too much. In northern New England, the rocks left by the glaciers for modern folks to deal with can be a nightmare when planting a new garden. Each spring brings forth a new crop, as well. Tools are damaged and the spirit of the gardener can be damaged as well. Gardeners recognize this battle for what it is. So what’s one to do?
Rather than cursed as an obstacle, the presence of rocks in your soil may be seen as an opportunity to create a garden perfectly suited to its site. A rock garden (sometimes called an alpine or scree garden) that uses the existing stone and gravelly soil to provide the correct planting area for specific plants will, with a bit of planning, be a delightful, low-maintenance and beautiful success. Since stones also collect and reflect the sun’s warmth and light, you will choose plants that enjoy such warm spots. Although rock gardens may be planted in shady areas, we have found that the majority of plants we prefer to use prefer 6-8 hours of full sun. The first days of spring in a rock garden are wonderful, as this will often be the first place to thaw out and warm up. Working in cooperation with nature usually ensures our success, we have found.
So how does one do it?
The Soil
When planning your garden, begin with evaluating the soil and planning for appropriate amendments. In this case, it is barely that. Rockery plants have adapted to the most desolate, forbidding locales on the planet. Think of a windswept mountain and recognize that the plants suited for a rockery thrive there and will suffer if over-fertilized. They have adapted to what seems to be impossible growing conditions—some even have rubbery leaves that permits daily cycles of freeze and thaw!
So, when building your garden, imitate the mountains and provide a very well-drained, sandy, gritty mix—10” is not too much. Do not add compost, manures or other fertilizers. Two parts of inorganic grit to one part of existing soil is a good ratio. You may incorporate sterile peat moss, as this will help discourage disease. Usually, this soil is alkaline, so avoid the use of acid-enhancing products. Remember that good drainage is essential.
The Plants
There is no single list called “Rockery Plants”. Instead, we select plants based upon their preferred conditions. Plants that like the weather hot and dry, the soil gritty and well-drained will thrive. No astilbe, please. Often, the roots will be very fibrous and very long. They anchor the plant and assure water and nutrients will be available deep below the surface, when needed. Some can actually take nutrition (nitrogen and minerals) from the rain. When planning, think of gray-leafed plants or ones with thick, succulent leaves. Think about plants that hug the ground or form tight buns of foliage. Usually, these kinds of plants will feel welcome in a rockery.
The Design
Art must imitate nature when planning a rockery. Random placement of stones will help visually reproduce the designs left on the mountains. Vertical stones should be buried approximately one half their size. This being said, you may wish to lay large horizontal slabs of stone flat on the surface. Avoid any repeated patterns. Try to reproduce the randomness of a mountain setting.
For more information about rock garden plants, please click on following links:
Victorian Trough Gardens for the New Millennium
Rock Garden Plants New for 2009