A collection of plants native to Japan was dispatched in 1828 to Leiden University in the Netherlands. Many were new to the West and welcomed into gardens there. One in particular attracted much attention. Discovered by the German physician and botanist Philipp Franz Siebold growing on the sides of volcanoes, by 1847 it was named 'the most interesting new plant of the year' by the Society of Agriculture and Horticulture in Utrecht.
The Royal Botanic Gardens at Kew received a sample three years later. By 1854 it had arrived in the Royal Botanic Gardens in Edinburgh. Soon it was being sold commercially by nurseries as an attractive and hardy ornamental plant. Japanese knotweed, Fallopia japonica, has never looked back..
Growing to ten feet or more tall, its roots can dive down the same distance. Plants may emerge 25 feet way from where first sighted. Concrete, bricks, stonework are no barrier. All of which pose a major problem when it comes to elimination. Many and interesting are the ways suggested to achieve this.
Amongst the more intriguing of these are vinegar, salt, caustic soda, diesel, gasoline even sour yogurt. Salad bars for goats have also been on the menu. "Hold a feminist conference next to it, the weed will die rather than listen" comes from a presumably male source. Digging obviously isn't going to do much good. In fact, a pessimist offers they are "waiting for the 'plant lives matter' protesters to come when they excavate the plant." One gardener wants to know why it cannot be grafted to his tomatoes so they grow as fast. Presumably tired of marijuana, another wonders if it is any good for smoking. Take me to your weeder indeed.
The only effective answer, experts agree, is to wage chemical warfare. The preferred assault weapon is glyphosate, applied as shoots first appear and repeated as needed. It may take three or more years to entirely eliminate all growth
It is hard to totally blame this junior Triffid on von Siebold. While in Dutch service, he was posted to Japan. Hailed for introducing Western medicine there, he also established a compact botanic garden during his sojourn 1823-29 with over 1,000 specimens. One of these was a new hydrangea which he named H. otakusa after the nickname for his Japanese mistress, Kusumoto Taki. And what would temperate region gardens today be without Hosta sieboldiana?
Wes Porter is a horticultural consultant and writer based in Toronto. Wes has over 40 years of experience in both temperate and tropical horticulture from three continents.
