How does extreme heat and drought affect invasive plants?
DO HEATWAVES KILL KNOTWEED?
A common misconception this!
Climate change is undoubtedly forcing plants into a ‘survival of the fittest’ mode, and this can be seen clearly now during the current heatwaves hitting most parts of the UK. While other plants will struggle in the drought due to a lack of water, a lot of invasive non-native plants (INNS), such as the most resilient of them all – Japanese knotweed carry on almost unphased! This plant can survive extreme temperatures from prolonged heatwaves to sub-zero.
But Japanese knotweed is not the only invasive plant to flourish in heat – others such as Himalayan balsam have a greater tolerance to heat then a lot of our native species, and when the rains return, any flooding that occurs provides the perfect conditions right now for their seed dispersal to be carried down watercourses (streams, rivers, gullies etc) to create new colonies.
Does extreme heat kill invasive plants?
Does extreme heat kill invasive plants?
Many homeowners assume that hot, dry weather will kill off invasive plants, but this is a common misconception. Although the visible stems and leaves may show signs of stress such as wilted leaves and stems – during periods of drought, many species remains alive. Take Japanese knotweed and Bamboo – both have extensive rhizome systems that conserve and store energy, allowing them to pick up when conditions become more favourable. The majority of non-native plants have a greater resilience to heatwaves than our native plants, so you may see (for instance) knotweed being more prevalent as other plants die back completely.
Homeowners should continue to be vigilant for Japanese knotweed and look out for reddish-purple shoots, bamboo-like stems, zig-zag patterned growth and shovel-shaped leaves. Japanese knotweed can spread rapidly because even small fragments of the plant’s underground rhizome system can develop into new growth.
Jennifer Holmes of Environment Controls states: “Although invasive plants do not directly kill other native plants, their aggressive growth can quickly dominate an area by blocking light and taking up space, making it difficult for surrounding vegetation to compete. We therefore urge homeowners not to cut, dig up or attempt to remove suspected invasive plants themselves, especially rhizomatous plants such as Bamboo and Japanese knotweed, as disturbing the roots can spread fragments and make the problem more difficult to manage.”
If you spot what looks like knotweed or any other suspect invasive plant in your garden, use our identification tool to confirm it before taking steps to treat it.