Reynoutria japonica seed
LATIN NAME: Reynoutria japonica
COMMON NAME: Japanese Knotweed, Asian Knotweed, Fleeceflower
Japanese knotweed is one of the most vigorous plants on earth, and it has a story like no other. It grows as a tall, vigorous perennial, reaching two metres or more in a season, with hollow, bamboo-like stems that are reddish and speckled, and large, shield-shaped or heart-shaped leaves. In late summer it bears long, airy plumes of tiny, creamy-white flowers that bees love. It is a plant of extraordinary strength, spreading quickly by its underground stems, and in its native East Asia it is a useful, valued plant, while in Europe and North America it has become one of the most famous invasive weeds of all.
Japanese knotweed belongs to the knotweed family, Polygonaceae, and it is native to Japan, China and Korea. It has been carried around the world as an ornamental, and its young stems are edible, and it is also grown by beekeepers, since its late flowers are valuable to bees.
Positive & Encouraging Seed Germination Guide
Growing Japanese knotweed from seed is easy, and it is a fascinating plant to grow for its edible shoots and its value to bees. The small, triangular seeds germinate readily in warm, moist conditions, so sow them in spring in pots of seed compost, cover them lightly, and keep them warm, bright and evenly moist. Germination usually begins within two to four weeks. Pot the seedlings on as they grow and plant them out in a sunny or partly shaded spot in reasonably good soil, where they will grow with astonishing vigour. If you are growing it for its edible spring shoots or for the bees, it will reward you well, though in mild climates you will want to keep it contained.
Scientific Research & Plant Biotechnology
Japanese knotweed has an exceptionally rich and divided record in research. In Europe and North America, it is one of the most studied invasive plants in the world, and researchers have examined its astonishing spread, its ability to grow through concrete and foundations, its control and its impacts, making it a central case study in invasion biology and in the study of how to manage difficult weeds. At the same time, the plant has been studied in phytochemistry for its valuable compounds, including resveratrol and related polyphenols, which have been studied for their antioxidant and other biological activity, and it has a long history of use in traditional medicine in its native Asia. For a plant that is both a serious weed and a source of promising chemistry, Japanese knotweed has one of the richest records of research of any plant.
Ecological & Economic Value & Wide Applications
Ecologically, Japanese knotweed is a divided story. In its native East Asia, it is a useful plant that feeds bees with its late flowers, holds soil and provides edible shoots, while in Europe and North America, where it has been introduced, its extraordinary vigour can crowd out native plants and damage buildings, so it must be managed with care.
Its economic value is real and surprising. The young shoots are eaten as a vegetable, the plant is valued by beekeepers for its late-season nectar, and its roots and stems contain compounds, including resveratrol, that are used in supplements and studied in medicine. For a grower in its native range, it is a useful and productive plant, and for anyone interested in plant biology, it is one of the most remarkable and debated plants in the world.