Identifying and managing Montbretia

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Scientific name: Crocosmia × crocosmifolia

Perennial plant (herb) in the Iris family (Iridaceae)

What is Montbretia?

• Long-lived (perennial), polycarpic (flowers many times) competitive dominant.
• Growth from a below ground corms (bulbs) and rhizomes (roots) early in the growing season – long slender leaves form a dense, compact canopy which restricts native plant species access to light.
• Decomposing leaves form a thick mulch that limits germination of native plant species.
• Growth from a below ground corms (bulbs) and rhizomes (roots) early in the growing season – long slender leaves form a dense, compact canopy which restricts native plant species access to light.
• Long-lived (perennial), polycarpic (flowers many times) competitive dominant.

How does Montbretia grow and spread?

• Reaches up to 0.6m tall in full growth.
• Montbretia spreads by direct rhizome (root) expansion and continuous corm (bulb) production; vegetative (asexual, clonal) dispersal of fragments of plant material created by human activities (e.g. disposal of garden waste) and natural disturbance processes (e.g. flooding).
• Seed are formed in the UK and Ireland, though the seed is not viable.

Where does Montbretia grow?

Common habitats where Montbretia is found include:

• Garden plantings
• Roadsides
• Railway embankments and cuttings
• Waste ground and spoil-tips
• Rivers and other watercourses (riparian habitats)
• Woodlands

Timing of Montbretia growth stages and treatment application

Timings of Montbretia growth stages are shown below along with recommended treatment timings.