- 1). Harvest or buy Japanese knotweed stems that are between 6 and 24 inches long and at least 3/4 inch in diameter. Stems that are longer than this become bitter and woody. If harvesting knotweed, look in moist locations such as near riverbeds or other areas of water and cut the stalks near the ground using a sharp knife or pruning shears.
- 2). Fill a sink 1/2 to 3/4 full of water and place all of the Japanese knotweed into the water. Rub the knotweed gently with your fingers to dislodge any dirt and sand that is on the plants. Remove the knotweed from the water and lay it on top of a towel to dry.
- 3). Remove all of the leaves from the knotweed plants by grasping them and pulling downward with your fingers. Discard the leaves since they have a tough, chewy texture and are not usually eaten.
- 4). Peel the outer layer off each of the knotweed stems using a vegetable peeler.
- 5). Slice the Japanese knotweed using a knife. You can cut the stems into any desired shape.
- 6). Fill the bottom pot of a steamer with two to three cups of water, or the amount recommended by the steamer manufacturer. Place the pot on a stove burner and turn the burner to high.
- 7). Place the knotweed into the steamer basket and insert the basket into the bottom part of the steamer. Place the lid on top of the steamer pot and allow the knotweed to cook until the stems are tender.
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