Montbretia (Crocosmia x crocosmiiflora) is a vigorously growing, long-lived bulbous plant that dies back annually. It is grass-like in appearance and often mistaken for Watsonia. It has strap-like leaves around 30 to 80cm long and 1 to 2cm wide.
It was a popular garden plant due to its bright orange trumpet-shaped flowers, which form in two rows along each stem. The aboveground foliage is short-lived, and grows back each year from underground 'bulbs' (i.e. corms) and creeping stems (i.e. rhizomes).
Montbretia grows in dense clumps and is capable of adapting to a variety of conditions. It out-competes native plants, particularly in native bushland and riparian areas. Montbretia can sometimes still be found for sale at local fetes, nurseries and markets, despite the ban on sale in NSW.
Dispersal: Montbretia mostly spreads from underground runners and bulbs. Bulbs can be transported to new locations by dumped garden waste, water and movement of contaminated soil. New plants also develop from the tips of the creeping underground stems (i.e. rhizomes)
Removal: To save you time and energy the most effective removal of Montbretia is just before full flowering occurs around Spring and Summer, digging out bulbs when the soil is wet. Hand removal is only practical for small clumps of the weed. Use a garden fork to dig all corms and underground stems to ensure complete removal. Cut stems first if the plant is in seed. Spraying with herbicide or using a weed wand is another option.
Grow Me Instead
Leek lily (Bulbine bulbosa)
An Australian native plant, leek lily is an attractive species with fragrant yellow flowers. It is especially suited to rockeries and cottage gardens and is also excellent as a container plant.
Blue flax lily (Dianella spp)
Flax lily is native to Australia. It has richly hued blue flowers with delicate yellow anthers that contrast well with the long linear form of the leathery leaves.
Day lilies – Hemerocallis species and hybrids
Day lilies have generous clumps of strappy leaves, and tall flower stems with double or single flowers in a wide range of colours.