It tends to displace other plants while it spreads, and it's difficult to eradicate. You can eat Japanese Knotweed in the early Spring only. Later, it becomes too tough. Japanese Knotweed has a tangy, tart flavour similar to rhubarb, only better. Taller stems, up to 1 ft. tall, have a tough rind that you must remove.
Smaller plants provide less food.
Be sure to discard all leaves, which are too tough to eat. Slice the stems, steam them, or simmer them. They're tangy and tart, with a flavour similar to rhubarb, only better. If they're too strong-tasting for you straight, dilute the tartness by using them as one ingredient out of many in a soup or stew. Like rhubarb, you can also use the tart flavour of Japanese Knotweed to offset the sweetness of fruits in jams or dessert dishes.