What is an Alpine?
Alpines are plants that naturally grow in high elevation areas. In these harsh climates, the plants often have to deal with long, cold winters, strong winds, intense sun during the short summer, and periods of drought. To protect themselves from the elements they hug the ground, resulting in diminutive plants; many alpines are miniature versions of familiar border plants. Because their season is short, many alpines produce large, vividly colored flowers in profusion to attract pollinators as efficiently as possible.
Why Grow Alpines?
Alpines are difficult to match for their rugged hardiness, being well-equipped for Alberta’s difficult climate. They will shrug off our winters, and many tolerate drought well or prefer dry conditions. The majority flower early in spring, showing off their intense colors at the first sign of warmth, and enduring through spring snowfall. With disproportionately large flowers and/or interesting foliage texture, mat-forming alpines are some of the best groundcovers around. An alpine garden combines contrasting architecture of plants and rock, bringing glorious mountain vistas into your own private space. Low-maintenance, beautiful, and hardy: what more could you ask for in a plant?
What do Alpines Need?
- Sharp drainage – the most important requirement. Heavy clay soils must be improved with organic material such as compost, as well as sand, and horticultural grit or limestone chips.
- Soil pH – most alpines prefer slightly alkaline soil. Using limestone chips or dolomite lime will achieve this. A few alpines like acidic soil; check plant signage for more information.
- Sun – alpines have varying sun requirements. Most grow fully exposed on sunny scree in nature, and so want full sun in the garden. Some grow in more sheltered conditions or at very high elevations where it is cool and thus do not fare well in hot afternoon sun. Check plant signage for more information.
- Scree: The most conventional type of alpine garden, the scree mimics a rocky mountain slope, where alpines are typically found in nature. You can get as three-dimensional as you want with a scree, building a slope as high or steep as you wish, or creating layers defined by large rocks. The scree is suitable for most types of alpines; plants that prefer shade or more sheltered conditions can be planted on the north or east side of larger rocks, where a microclimate is formed.
- Crevice garden: The crevice garden is a stunning and effective way to grow alpines. Layers of vertical rock (often shale) are placed close together on a slope with sharply-drained soil between the rocks. It is in these crevices that the alpines are planted. This style of garden works especially well for smaller cushion-forming plants and species that require a more sheltered location, as the crevices provide that microclimate and mimic what the plants would experience in nature.
- Trough: A trough is a shallow container designed for growing alpines in, most often constructed out of hypertufa, a relatively lightweight man-made rock. Planting a trough allows you to create a miniature, portable alpine garden. Fill your trough with potting soil, mixed with a generous amount of horticultural grit or Axis soil amendment. Do not use garden soil. Top-dress with grit or limestone chips. You can get creative with troughs, adding decorative rocks to complete the look.
- Retaining walls: You can also create an alpine garden using a retaining wall; place mat-forming plants near the edges to trail over the sides. Various sized rocks and other plants will add layered dimensions to make it interesting. Get super-creative by building a retaining wall in the style of a crevice garden, and planting alpines directly into the crevices in the wall.
- Tufa rock: This porous, lightweight material is naturally-occurring. Pieces of tufa are aesthetically pleasing in an alpine garden but can also be planted directly into, creating an ideal environment for growth. Drill a hole into the rock and partially fill it with soil mix, then plant into the hole. This works best for seedlings and younger plants.
Types of Alpines
Androsace (Rock Jasmine)
These delightful late spring to summer blooming plants are mat- or cushion-forming and are often quite prolific in the garden, self-seeding and spreading by stolons. The fragrant, yellow-eyed flowers are in shades of white, pink, and magenta.
The evergreen foliage of the mat-forming Spanish sandwort (A. tetraquetra) provides essential texture in the rock garden. The white flowers, appearing in summer, are a bonus.
Alpine forms of this popular garden plant are must-haves, and may form mats, small clumps, or hummocks. They are profuse bloomers from late spring to early summer.
The quintessential alpine plant, trumpet gentian (G. acaulis) forms mats that are smothered in large, true blue flowers in late spring. Spring gentian (G. verna) blooms a little earlier, with electric blue to deep blue blooms.
These succulents have an especially high need for perfect drainage, but in a hot and dry location, their incredible late spring to early summer blooms in a rainbow of colors will really wow you. Plant the crowns directly on sand to protect from rot.
Alpine species of beardtongue tend to be woody, spreading plants that make excellent groundcovers. Evergreen foliage is coupled with tubular flowers from late spring to midsummer, attracting butterflies and hummingbirds.
Moss phlox (P. subulata) and Douglas’ phlox (P. douglasii) selections are commonly used in alpine gardens. They will form a mat which will be almost completely covered in bright colored flowers in spring. They are relatively long-blooming as well.
Alpine Primula species are royalty among plants. Selections of P. marginata, P. allionii, P. auricula, and various hybrids are stunning when they flower from spring to early summer. These must have perfect drainage coupled with consistent moisture, and do best with protection from hot afternoon sun.
No alpine garden is complete without at least a few members of this diverse group. From compact rosettes or tightly-clustered cushions of foliage, plants can have anything from a profusion of nearly stemless flowers to tall and majestic sprays of blooms, held high above the leaves. They appreciate sharp drainage, consistent moisture, and protection from hot afternoon sun.
Sempervivum (Hens & Chicks)
These succulents form tightly clustered rosettes of foliage, in a multitude of colors, which spread to form a mat. Excellent for hot and dry rock gardens. Also try the related houseleek (Jovibarba) and Chinese dunce cap (Orostachys)!