© Christian Harboe Nielsen, some rights reserved (CC-BY) · GBIF
Chamaenerion spp.
willowherb
Northern Hemisphere (boreal and montane)
Overview
Chamaenerion spp. is a genus of perennial herbs in the evening-primrose family, Onagraceae, of the cool and cold Northern Hemisphere, sometimes merged with or split from Chamerion spp.. The group includes the fireweeds and rosebay willowherbs, upright plants 1 to 8 feet (30 to 240 cm) tall that spread by creeping roots and wind-blown seed. Stems are usually unbranched and clothed in narrow, willow-like leaves arranged spirally or nearly opposite. Spikes of four-petalled flowers in rose-pink to magenta, sometimes white, open from the base of the spike upward over many weeks in summer. C. angustifolium, the common fireweed, is the tall, pink-flowered species that quickly colonises burned ground, clearings, and roadsides, while C. latifolium, dwarf fireweed or river beauty, is a low alpine and arctic plant of gravel bars. After flowering, slender pods split to release many seeds carried on silky white hairs. Plants die back to the ground in winter and regrow from spreading roots, forming large stands. They favour open, disturbed, moist ground and full sun.
Native Range
Chamaenerion spp. is native across the cooler Northern Hemisphere, including northern and montane North America, Europe, and Asia. C. angustifolium is circumboreal, while C. latifolium ranges through the Arctic and high mountains.Suggested Uses
Grown in wild and naturalistic plantings, meadows, and pollinator and habitat gardens, with the tall fireweeds suited to large informal areas and the dwarf species to alpine and gravel beds. The nectar-rich flowers draw bees and butterflies, and fireweed is a major honey plant. The spreading habit limits use in small, tidy borders.How to Identify
Appearance
Size & Dimensions
Height1' - 8'
Width/Spread1' - 3'
Bloom Information
Flowering runs through summer, roughly June to September, with each spike opening from the base upward so that buds, open flowers, and seed pods appear together. Bloom lasts many weeks. The flowers are rich in nectar and heavily worked by bees.
Detailed Descriptions
Flower Description
rose-pink to magenta, sometimes whiteFoliage 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
Plants grow in full sun to light shade in moist, well-drained soil of moderate fertility, across a wide pH range from acidic to neutral. They tolerate poor, disturbed, and recently burned ground and spread fast by creeping roots and seed, so they can become invasive in gardens and are usually contained or given room to roam. Cutting back before seed sets limits self-sowing. They are cold-hardy and die back each winter, returning from the root system. Division in spring or autumn renews clumps. Plants have few pest problems but can spread beyond their intended space.Pruning
Cut flowering stems back after bloom, before the pods ripen, to limit the spread of windborne seed. Stems are cut to the ground in late autumn or early spring as they die back. Lifting and dividing congested clumps controls their spread.Pruning Schedule
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fall