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The Seed Exchange

wanted Japanese knotweed seeds

13 years ago

I have a number of seeds right now: raspberry monarda,

Campanula Telham Beauty, double and single shasta daisies,

Pink Parasol Echinacea,

Featured Answer

infiniteohms

13 years ago

This is a extremely invasive plant, if you are 100% sure you want to grow it (which i would strongly advise against) please be very very very careful and be sure to keep it in a buried pot and dont let it go to seed, ever. I have seen it send runners 30+ ft under a parking lot and roots 10'+ into the ground, scary stuff.

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Comments (13)

gardenweed_z6a
13 years ago
Ditto what infiniteohms said--this plant is taking over much the same way bittersweet vine has in the northeast. It is nearly impossible to kill and has proven to be extremely difficult to remove once it's established. It can grow 12'-15' tall and is listed with many other invasive species on most states' lists. It chokes out native species which reduces habitat & food sources for not only birds & butterflies but other critters as well.

If you don't want to take just our word for it, Google Polygonum cuspidatum. It has been classified as invasive in several countries.

http://www.invasivespeciesinfo.gov/plants/knotweed.shtml

There's a link on this site entitled, "Japanese Knotweed - Plant Invaders of Mid-Atlantic Natural Areas." It's probably worth checking before you plant something you'll never be able to get rid of.
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There seems to be confusion in this thread between "invasive" (aggressive proliferation causing significant displacement or harm to native populations of plants and/or animals) and "aggressive" (rapidly spreading growth in a localized area). Just because you don't see a plant colonizing the area near where you planted a specimen, doesn't in any way mean it's not invasive and causing problems. Also, just because you do, doesn't mean it is invasive. One reasonable way to make a decision about whether, in regards to potential for invasiveness, a plant should be planted in a particular area (state, part of the country, etc) is to review reports from appropriate state agencies or organizations like Exotic Pest Plant Councils. If a plant is reported to be an invasive problem in your area, then planting it is probably not an an environmentally responsible thing to do. If, on the other hand, there is no issue anywhere around your (in your part of the country), then plant away and enjoy.
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I have seen very well behaved varieties and of course there are the incredibly invasive varieties. These pictures look a lot like the variety I had. I planted 4 of these from 3" pots about 3 years ago. I needed to remove them this year for an irrigation system. After 4 weeks of repeated applications of glyphosate, I ended up having to dig them out of the ground. The roots were 2-3 feet deep. It's an incredibly tough plant. More like a very hardy shrub that grows anew each year than a typical perrenial. It was a pretty plant when they were young then they were a huge nuissance. I was constantly pruning to keep them under control. I would not recommend them unless you want them to take over a fairly large portion of your yard. Aaron Here is a link that might be useful:
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Is pokeweed considered an invasive native? I have not seen it spread as aggressively as JKW. I transplanted a Redtwig from the JKW infested area to my daughter's sandbox/planting heeling area, and the JKW has started to spread out from the small root that was inadvertently transplanted there. Being sand I can pull the rhizomes out and look for the main tap roots. Kinda like hunting for treasure. ON a postive note JKW is a source of an organic fungicide and apparently more palatable for eating than pokeweed. However the herbivore means of control doesn't seem to appeal to me very much. Maybe if the recession gets worse the JKW will look more appetizing?
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Hi, I think I've had some success with my nemesis, also. I read a lot about it, and last spring decided to attack it. I dug up as much of the rhizomes and runners as I could. I then put tarps on as much as I could, all summer. I still got some that grew around the edges and popped up through holes and seams in the tarps. I started using the strongest Roundup (I think it's called Pro) with the highest percentage of glycosophate (sp.?) in it. I removed the tarps in October and zapped the remaining knotweed with it. This past spring I had about 80 percent less knotweed, and it now doesn't get very high. I had some anxiety early on when I noticed two plants had sprung up in areas that were not close by, as well as in my neighbor's yard. That scared me but I figured that it might have seeded from my dragging the dried up (supposedly) pieces to the trash. Then everything started looking like knotweed and I got confused and started squirting everything, including ragweed and pokeweed. I'll zap the remaining knotweed with the Roundup Pro again and see what happens next spring!
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PRO
Westeast Herb Gardens
5 years ago
I need some japanese knotweed plant and/or seeds. Let me know if you have
Mick Wildman
5 years ago
where can I buy Japanese knot weed, either seeds or cuttings. what is the best toget it to grow
PRO
Len NW 7a
5 years ago
I have it growing at our place and it is very difficult to stamp out. Sincerely advise you never plant this stuff.
HU-504357360
5 years ago
I emphatically advise do not plant Japanese Knotweed. It is highly invasive, super hardy, and is on the noxious weed list in some states-Minnesota is one. It destroys native habitats, and is difficult to eradicate. Please, be responsible with any non natives, and esp. this one
Socair SocairNone
4 years ago
Does anyone please know where I can buy some Japanese Knotweed plants or seeds.

And please no lectures from the self appointed garden police.
H Kavarana
4 years ago
It would be illegal in Utah, and I know in at least some other states as well.

https://rules.utah.gov/publicat/code/r068/r068-009.htm#T6

9. Noxious Weeds Distributed or Sold for Any Purpose.

a. It shall be unlawful for any person, company or corporation to sell, barter or give away any noxious weed plants or seeds for any purpose.
Gichard Romes
3 years ago
I too would like to get some knotweed plants / seeds / shoots, but this request is to send it back to Asia, if possible.
Passiflora Collector
3 years ago
It’s considered a noxious weed in most areas, so the “garden police” would be your local county who can fine you in addition to cost for removal on your property anywhere you’ve allowed it to spread. Where I am at it keeps getting spread by flood waters and taking over the entire riparian zone and spreads from there.

I would hope people are just trying to troll and aren’t seriously considering planting this intentionally. How about some kuduz while you are at it?
PRO
Len NW 7a
3 years ago
bad seeds bad seeds
Virginia Webster
2 years ago
Sounds like a person would get less heat openly planting pot in their front yard. It would be nice to have greenery in drought stricken dirt where nothing else can grow anyway. Geessh....garden police is right.
HU-140964624
2 years ago
yeah pot is not invasive so go for it, Virginia

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