When you admire the pretty clusters of creamy white flowers that adorn Japanese knotweed plants during August, it’s easy to see why 19th century gardeners were so taken with this impressive new ornamental plant when they discovered it at the Royal Botanic Gardens in Kew and other nurseries throughout Europe. Bees love it too and can often be seen crowding around the delicate tassels of tiny flowers, attracted by its colour, fragrance and the sweetness of its nectar.
Yet the humble bee is not responsible for the spread of Japanese knotweed across the country. While the plant is capable of reproducing sexually, where the pollen from the male plant fertilises ovules in the flower of the female plant, there are no male Japanese knotweed plants in the UK.
Instead it spreads through vegetative reproduction, where a shoot grows from the rhizome or stem of a parent plant and successfully establishes itself as an independent plant which is able to survive without support.
Japanese knotweed has an incredible ability to reproduce vegetatively, from tiny fragments of rhizome the size of a fingernail. In a laboratory experiment we conducted at our headquarters in Send, Surrey, back in March, we achieved successful regrowth from a thin piece of rhizome weighing just 0.2g!
Of course, humans are always on hand to help knotweed spread through vegetative means, by mowing and strimming, illegally dumping knotweed waste and even just disturbing the ground where the plant is growing.
Homeowners who try to dig knotweed out of the ground themselves are highly unlikely to find and remove every tiny particle of rhizome from the ground, meaning the knotweed will simply regrow. It’s a job best left to the professionals, so contact Environet today to arrange a survey.