Virginia Knotweed

Biological Name:

Polygonum spp. (Virginia-Knotweed)

Natural Habitat:

The Virginia-Knotweed is a perennial plant that can be found growing in damp and shaded areas, such as along streams and rivers. It is native to the eastern United States, including the Virginia region.

Description:

Virginia-Knotweed is a perennial herb that is native to North America. It has narrow pointed leaves and small white flowers that bloom in the summer. It spreads by rhizomes and can be aggressive in garden beds.

Frequently Asked Questions (FAQs)

Q: Is Virginia knotweed edible?
A: It is a member of the buckwheat family and is native to eastern North American. Virginia knotweed is edible by boiling the young leaves. It is related to an Asian cousin, Japanese knotweed, that is delicious to eat.
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Q: Should I pull out knotweed?
A: The plant will not resprout from the cut cane, but removing them may aid in finding and treating resprouts in an infested patch. The area will also be more conducive to revegetation if the cut canes are removed. Glyphosate concentrate- Glyphosate is a non-restrictive use herbicide.
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Q: What happens if you touch knotweed?
A: Japanese knotweed is not poisonous and is not harmful to touch, however, always use caution to avoid inadvertently allowing the infestation to spread.
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Q: What happens if you burn knotweed?
A: The burning of Japanese knotweed is an effective way to eradicate it from a site, but only when the plant is absent of moisture. Here, you need to ensure that the strands of the plant are fully dried out. Once this has happened, the knotweed can be properly burnt, ensuring there is no possibility of it regrowing.
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Q: Is knotweed good for anything?
A: Knotweed is an herb. The whole flowering plant is used to make medicine. Knotweed is used for swelling (inflammation) of the main airways in the lung (bronchitis), cough, sore throat, a mild form of gum disease (gingivitis), and other conditions, but there is no good scientific evidence to support these uses.
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Q: Why should you not cut Japanese knotweed?
A: If you do find Japanese knotweed on your property it is most important that you prevent further spread of the plant. Do not strim, cut, flail or chip the plants as tiny fragments can regenerate new plants and make the problem even more difficult to manage.
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Q: Can knotweed be killed?
A: Spraying or injecting the stems with chemicals can be an effective treatment to stop knotweeds spreading. You must only use approved herbicides. You’ll have to respray. It usually takes at least 3 years to treat Japanese knotweed.
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Q: Is persicaria virginiana invasive?
A: Persicaria virginiana is not an invasive plant —this is a native species. And although some cultivars —including ‘Painter’s palette’— may self-seed, in my experience this Persicaria virginiana cultivar is easily managed, well behaved, and non-aggressive.
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Q: Is Persicaria the same as knotweed?
A: Persicaria is a genus of herbaceous flowering plants in the knotweed family, Polygonaceae. Plants of the genus are known commonly as knotweeds or smartweeds. It has a cosmopolitan distribution, with species occurring nearly worldwide. The genus was segregated from Polygonum.
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Q: Should Persicaria be cut back?
A: Persicaria are trouble free plants to grow so do not require much maintenance. Cut back after flowering.
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Q: How big does Rosa virginiana get?
A: Virginia Rose is a woody perennial suckering shrub and grows 4-6 feet tall. It is the best of the native roses to grow in the garden. It has pink open flowers in June to Aug. and the stems have numerous hooked prickles.
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Q: Is Persicaria poisonous to dogs?
A: Is Persicaria odorata poisonous? Persicaria odorata has no toxic effects reported.
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Q: How do I get rid of Persicaria?
A: (pulling, cutting, disking) Cultivation or hand removal can control these weeds. Mowing before flowering can reduce seed set. Tillage is not generally an option in wet areas. These plants grow in wet locations, so burning is not a feasible control method.
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Q: Do slugs like Persicaria?
A: Slugs and snails may make an impression on the foliage of Persicaria virginiana and its cultivars, but even they are not bothered too much.
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Q: Is knotweed native to Virginia?
A: Earlier classified as Polygonum virginianum or Tovara virginiana, this native commonly occurs throughout much of the Mid-Atlantic Region.
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Q: Can you dig out knotweed?
A: Small clumps of Japanese knotweed are fairly straightforward to manage and can be removed by the home gardener by digging or spraying with weedkiller. However, we recommend you hire a qualified, professional company to control large clumps.
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Q: Is knotweed serious?
A: Japanese knotweed can do extensive damage if left untreated. While it can’t grow through bricks and concrete, it can work its way through small cracks and gaps. It can cause damage to foundations, patios, walls and more if ignored. This is why mortgage lenders take it seriously.
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Q: What is the difference between knotweed and Japanese knotweed?
A: One of the most identifying features of the Knotweed are the leaves. Japanese knotweed leaves are shovel-shaped (not to be confused with heart-shaped) with a point at the tip and staggered on the stem (one stem per node), creating a zig-zag stem growth pattern which is quite characteristic.
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Q: How do you get rid of knotweed naturally?
A: Cut Down and Remove the Canes One method is to use sharp pruning shears or loppers to take down the stems as close to the ground as possible, making sure to remove every last cut piece and fragment because as little as half an inch of the root or cut stem can grow into another plant.
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Q: Is it illegal to spread knotweed?
A: If you have knotweed on your land or property You do not legally have to remove Japanese knotweed from your land unless it’s causing a nuisance, but you can be prosecuted for causing it to spread into the wild.
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Q: Is Japanese knotweed in Virginia?
A: It has since spread in the wild and is now found from Nova Scotia to North Carolina. Japanese knotweed is widely scat- tered in Virginia. Japanese knotweed emerges in early spring and grows rapidly to heights of six to nine feet. It forms dense, nearly pure stands which crowd out native plants.
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Q: Should I worry about Japanese knotweed?
A: Japanese knotweed can do extensive damage if left untreated. While it can’t grow through bricks and concrete, it can work its way through small cracks and gaps. It can cause damage to foundations, patios, walls and more if ignored. This is why mortgage lenders take it seriously.
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Q: Does Japanese knotweed ever go away?
A: It usually takes at least 3 years to treat Japanese knotweed. Knotweed rhizome can remain dormant in the soil for many years and will regrow if disturbed or if the soil is relocated.
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Q: What happens if you dig up Japanese knotweed?
A: Digging the plant out of the ground can cause more problems in the long run, owing to its ability to regenerate from small pieces of root and the issues around its disposal. It is possible to gradually weaken the plant by removing all leaves as soon as they grow, which stops the plant photosynthesising.
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Q: Does Japanese knotweed devalue your house?
A: How much does Japanese knotweed devalue property? Japanese knotweed can devalue a property between 5-15%. There have been cases where homes have been almost completely devalued as a result of severe infestations, however, these are rare occurrences.
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About the author

Samuel is a gardening professional and enthusiast who has spent over 20 years advising homeowners and farm owners on weed identification, prevention and removal. He has an undergraduate degree in plant and soil science from Michigan State University.