I so enjoyed harvesting, cooking and eating Japanese knotweed today, for the first time in my life.
I found several patches of the plant locally and harvested using a small knife, in much the same way as you would asparagus, except above the ground. The more mature stems were hollow, younger ones were very like asparagus within. Some had thin stems, some fat. I harvested young shoots, about 6 to 8 inches long, took them home, stripped away the leaves and thoroughly washed the stems before chopping them and boiling for 5 minutes in a little water.
The taste was very rhubarby; tart, sour and in need of some sweet. Once cooled a little, I mashed the soft stewed stems with a little banana, homemade yoghurt, a dab of honey and a good pinch each of ground ginger and cinnamon. When combined to my liking, I served in a small bowl and garnished with torn basil leaves.
The outside of the knotweed was more fibrous than I had expected so next time, I shall either push the stewed stems through a fine sieve or pulverize them with a blender, before mixing with the other ingredients. Stringiness aside, this is a delicious dessert! Maida Silverwood’s book proposes freezing stewed knotweed and I shall certainly have a go at that, when I find more of it. I will also keep an eye on how the cut stems repair at my harvesting spot.
Please be aware of the rules for rhizome disposal for this plant in your locality. In some countries it is a criminal offense to allow spread of the plant by careless disposal of the roots.
The roots were apparently used in ancient Chinese medicine for menstrual and post partum problems. It is certainly very astringent to taste and thus must have a drying, constricting effect on the body, at least to some extent.
I’ll do some research into the similarities with rhubarb and more historic medicinal uses. It is truly delicious and if you are a rhubarb fan I am quite certain you could also come to love Japanese knotweed.