Koenigia alpina
alpine knotweed
Overview
Koenigia alpina is a clump-forming, herbaceous perennial growing 24–48 inches (60–120 cm) tall and 24–36 inches (60–90 cm) wide, with upright, branching stems rising each year from a woody rootstock. Formerly placed in Aconogonon spp. and Polygonum spp., it carries lance-shaped, pointed green leaves 2–4 inches (5–10 cm) long along the stems. From mid to late summer the stems are topped with loose, branched, airy panicles of many small creamy-white flowers that age to pinkish-brown as seed sets. The plant grows in mountain meadows and on slopes across Europe and Asia and tolerates a range of soils in sun, though it needs reasonable moisture, can flop in rich soil or shade, and self-seeds where conditions suit. Hardiness covers USDA zones 4–8. The foliage dies back to the ground in winter and reappears in spring. The dried seed heads stand into autumn. It is grown in mixed and naturalistic borders, meadow plantings, and wilder parts of the garden for its airy summer flowers.
Native Range
Koenigia alpina is native to the mountains of Europe and Asia, from the Alps and Pyrenees eastward across to central and northern Asia, where it grows in meadows, on slopes, and in open scrub.Suggested Uses
Koenigia alpina is grown in mixed and herbaceous borders, naturalistic and meadow plantings, and wilder parts of the garden. Its airy white summer flowers combine with grasses and other perennials in prairie-style schemes. The standing seed heads extend interest into autumn.How to Identify
Appearance
Size & Dimensions
Height2' - 4'
Width/Spread2' - 3'
Bloom Information
Flowering occurs from mid to late summer, usually July to August in the Northern Hemisphere, when branched panicles of small creamy-white flowers open over several weeks. The flowers draw bees and other insects. As seed sets, the heads age to pinkish-brown and stand into autumn. The dried seed heads give late-season structure.
Detailed Descriptions
Flower Description
Creamy white aging to pinkish-brownFoliage Description
GreenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grow Koenigia alpina in full sun to light shade in moist but well-drained, reasonably fertile soil. Water in dry spells, as the plant prefers steady moisture and may wilt in drought. In rich soil or shade the stems grow soft and can flop, so an open sunny site keeps them upright. Cut the stems back to the ground in late autumn or late winter once they die down. It self-seeds, so spent heads are removed where seedlings are unwanted. The plant is largely free of pests and disease.Pruning
Koenigia alpina is cut down to ground level in late autumn or late winter once the stems have died back. Spent flower heads can be removed earlier to limit self-seeding, or left for seed-head interest and wildlife. Clumps are lifted and divided in spring to propagate or control size.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fallwinter