What’s so appealing about this Knotweed? Is it the green and cream or white leaves with pale peach to dark red splotches on top? Is it the flowers – many tiny red or dark pink orbs on a long stem that appear above the leaves? Knotweed means tall, friendly color growing throughout the bed. Easy care makes it a keeper.
- Persicaria virginiana commonly called knotweed is a herbaceous perennial found in the U.S., Japan and Korea. It thrives in Zones 4-8.
- The leaf is oval. Green is the main color. Then it’s color on color: cream or white splotches topped by pale peach to dark red splotches. No two leaves look alike.
- Knotweed grows to about 24 inches tall. Its spread is one and a half to two feet wide.
- Bloom time is late summer, early fall. Tiny flower “knots” in red or dark pink bloom on a tall stem giving it the name knotweed. The second part of the name “weed” doesn’t apply to the variety Persicaria virginiana as it is not invasive. It spreads by rhizomes – thick looking roots that grow horizontally underground. It is also self seeding as the “knots” or flowers when dry, fall off and germinate. Pets sometimes sport little pink knots in their coats after brushing up against the stems. Where will the knots land?
- Attracts butterflies.
- Deer and rabbit resistant.
- Full sun to part shade is required for good growth.
- Soil is average, well drained.
- Water needs are medium which is to say they tolerate some dry weather, but biweekly watering keeps them looking their best.
- Maintenance is low. No cutting back. No dead heading the flowers. No significant pests or diseases. After winter the stems look like dry sticks coming out of the ground. These can be removed or crushed in place. New growth covers them up as they decompose.
Problems are Small
Sometimes knotweed winds up in places where it’s not wanted. Pulling it out is easy.
As a group they’re not dense enough to keep weeds from growing in between. If the weeds are below the height of the knotweed, they can’t be seen until closer inspection.
Another type of knotweed called Fallopia japonica is invasive in the U.S. It chokes out native plants and should not be grown.
Naturalizing is the easiest way to enjoy them in the garden. Variegated leaves and an easy growing habit fill in a space with good color. Knotweed contrasts well with the green of nearby bushes. They can also be used in container plantings if kept well watered. Cut stems of leaves and flowers to add an unusual twist to a bouquet.
Copyright 2018 Juli Seyfried