Japanese knotweed

Fallopia japonica ( syn. Reynoutria )

Japanese knotweed (Fallopia japonica synonym Reynoutria japonica) is an invasive plant species native to parts of Asia. This perennial herb can grow up to 3 meters in height and is known for its heavily branched, bamboo-like stems and large, heart-shaped leaves. It is an aggressive invader that can outcompete native species, so it is important to control its spread. However, the plant also has edible young shoots and medicinal uses. Its fast growth and densely branched stems make it useful in soil erosion control and as a shade provider.

Cycle:

Herbaceous Perennial

Watering:

Average

Propagation:

Seed Propagation

Hardiness Zone:

Flowers:

White Flowers In Summer

Sun:

Deep shade, Filtered shade, Full sun, Part sun/part shade

Fruits:

Fruits In Autumn Ready In

Leaf:

Yes

Leaf Color:

green,red,yellow,purple,orange

Growth Rate:

High

Drought Tolerant:

Yes

Salt Tolerant:

Yes

Invasive:

Yes

watering

Japanese Knotweed should be watered 2 - 3 times a week during the growing season. Water until the soil is lightly damp to the touch. Allow the soil to dry out slightly between each watering. In colder weather, reduce watering to once a week. During the winter months, reduce watering significantly, and only water when the soil is dry to the touch. Japanese Knotweed needs a lot of moisture to actively grow; however, it can become prone to disease if the soil is too wet for too long.

sunlight

Japanese knotweed, also known as Fallopia japonica (formerly Reynoutria japonica), prefers full sun exposure, with 5 to 6 hours of direct sunlight being optimal. Since this plant is native to the temperate areas of East Asia, it is best grown in USDA hardiness zones 4 to 9 and grows well in most soil types. It is important to note that this species can tolerate wet soil, but it may die back if the soil gets too dry in the summer months. Additionally, Japanese knotweed will tolerate shady areas but will not thrive in them, so full sun exposure is preferred.

pruning

Japanese knotweed (Fallopia japonica, syn. Reynoutria) should be pruned once a year, preferably at the beginning of April. Pruning should be done late enough that the plant doesn’t start flowering and seeding, but early enough that the new growth can develop before winter sets in. When pruning, all top growth should be removed to within 15-20cm from the ground. The pruned material should then be removed from the site. Pruning will keep the Japanese knotweed under control and reduce the amount of potential new growth for the next season.

Season

Fall

Winter

Spring

Summer

Sep

Oct

Nov

Dec

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Harvest Fruit

Harvesting of Fallopia japonica (syn. Reynoutria) typically begins in late summer, usually in August or September.

Starts Flowering

Japanese knotweed typically starts flowering in July.