Thick Japanese knotweed stalks
Home - Garden
Kill Japanese Knotweed In Your Yard With These Genius Tips
Japanese knotweed is an invasive perennial bush that spreads rapidly and is hard to remove. Methods that have shown promise include smothering or cutting it or using plant lice.
This plant can tolerate saline soil, drought, and high temperatures. It forms an extensive root system and colonies of shrubs rising 6 to 10 feet high, crowding out other plants.
Smothering this plant is effective, requires the least work, and doesn't disturb the soil. Leave it to grow through spring and cut it back to the ground in the first week of June.
Next, cover the area with a layer of mulch, followed by a thick dark tarp weighed down by cinder blocks, then add another layer of mulch. Leave the tarp undisturbed for five years.
Another method is to cut the stalks of the bush in June, July, and August every year for at least three years. This forces it to produce new shoots until its energy is depleted.
The biological method, which is approved in the U.S., uses Japanese plant lice or psyllids called Aphalara itadori that feed on the plant’s leaves and shoots, hampering its spread.