Butterfly Bush is a semi-evergreen shrub that can grow up to 5 m tall. It is an invasive plant that has escaped the confines of gardens in southern BC. It is native to China and was introduced to North America as an ornamental plant because of its large purple tubular flowers that are known to attract butterflies. Since it is a hardy plant that can be grown in a variety of environments, it has been a popular choice for gardens and landscaping. However, its ability to withstand challenging environmental conditions has allowed it to spread outside of cultivated areas to forests, meadows, riparian, and coastal habitats where it competes with native species like Douglas-fir.
Butterfly Bush reproduces abundantly. The flower clusters can produce over 40,000 seeds, which spread by wind and water, and can remain dormant in the soil for many years. Because of its fast and efficient reproduction, it can quickly crowd out native vegetation and form dense monocultures. Not only is it an efficient reproducer, but it can also change the structure of the soil by altering the nitrogen and phosphorus levels, which in turn may limit the growth of native plants in the area. Even the butterflies which give it its name are unable to survive solely with Butterfly Bush. Indeed, only adult butterflies can sip its nectar; butterfly larvae are not able to consume Butterfly Bush, and since it displaces natural food sources, it can actually harm butterfly populations.
Alternative native ornamental plants that grow well in sunny or shady locations in your garden include the Red-flowering Currant and Ocean Spray. You can learn more about ornamental alternatives to Butterfly Bush in the Grow Me Instead brochure.
SSISC’s goal is to contain the spread of Butterfly Bush to Squamish and south, eradicate it from Whistler and prevent it from establishing altogether in Pemberton. If you spot it north of Squamish, please remember to report it by clicking here or by emailing info@ssisc.ca.
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