Broadleaf sermountain: complete guide

Overview

Broadleaf sermountain (Laserpitium latifolium), also known as large sermountain, is a stately biennial to perennial plant from Apiaceae family (carrot family). This alpine plant originates from European mountains and grows at appreciable elevations in various mountain ranges. The plant is renowned for its impressive growth, large broad foliage, and delicate white flower clusters.

Appearance and bloom

Broadleaf sermountain reaches 60-100 cm in height. The plant first forms a basal rosette of large (up to 30 cm), triply-divided leaves with heart-shaped leaflets. In the second year or later, a thick, green stem with numerous side branches emerges. Flowers appear July-August in large, flat white flower umbels of 5-10 cm diameter. Flowers range from white to light pink. Fruits are flat, oval seed-bearing structures with broad wings.

Ideal location

Broadleaf sermountain grows optimally in part shade to sun. Plant locations with morning sun and afternoon shade are ideal. The plant thrives with ample moisture but not waterlogging. This plant tolerates wind and cold winters (USDA zones 5-8).

Soil

Broadleaf sermountain prefers nutrient-rich, well-draining soils with moderate moisture. pH 6.5-7.5 is optimal. Acidic soils (below pH 6) should be amended with lime. The plant grows well in both sandy and clay soils.

Watering

Regular watering during growing period (May-October) is important. Provide approximately 2-3 liters per two weeks during dry spells. The first two years require consistent watering for good establishment. Mature plants tolerate drought better but grow better with moderate moisture.

Pruning

Remove spent flower stems in August-September for a neater appearance and to limit self-seeding. The plant can regenerate if you do not damage basal leaves. Hardy parts can be removed in December-January.

Maintenance calendar

• April-May: Stake young plants; water regularly
• June: Flower stem emergence; water continuously
• July-August: Flowering complete; reduce watering
• August-September: Seed stage; remove stems if desired
• October-March: Rest period; minimal watering

Winter hardiness

Broadleaf sermountain is hardy in USDA zones 5-8 (-29 to -12°C). The plant forms a winter-hardy basal leaf rosette. Extreme frost can damage young plants, but mature plants usually recover.

Companion plants

Broadleaf sermountain combines well with other alpine plants such as angelica, heracleum, and other Apiaceae. Plant around with alpine flora such as primulas and lupines. In mixed borders, this plant creates structure.

Closing

Broadleaf sermountain is perfect for those seeking a stately alpine plant with interest in flowers and structured form. This is not for small gardens but offers beauty in larger, more naturalistic settings. Discover alpine plants and grassland design on gardenworld.app. Get inspired for natural gardens on gardenworld.app.