Our annual end-of-summer contest is here, come on down to the Dave's Garden County Fair!

Giant Knotweed

Fallopia sachalinensis

Family: Polygonaceae
Genus: Fallopia (fal-OH-pee-uh) (Info)
Species: sachalinensis (saw-kaw-lin-YEN-sis) (Info)
Synonym:Polygonum sachalinense


Unknown - Tell us

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Unknown - Tell us

Where to Grow:

Unknown - Tell us


10-12 ft. (3-3.6 m)


Unknown - Tell us


Unknown - Tell us

Sun Exposure:

Unknown - Tell us


Unknown - Tell us

Bloom Color:

Unknown - Tell us

Bloom Time:

Unknown - Tell us


Unknown - Tell us

Other details:

May be a noxious weed or invasive

Soil pH requirements:

Unknown - Tell us

Patent Information:


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

Seed Collecting:

Unknown - Tell us


This plant has been said to grow in the following regions:

Minneapolis, Minnesota

Hamden, New York

Gardeners' Notes:


On Jul 22, 2009, Malus2006 from Coon Rapids, MN (Zone 4a) wrote:

Look like a very massive version of Fallopia japonica - this will behave itself for 4 to 5 years - after that it will start becoming more aggressive, sending rhizomes deep in the ground going horizontally about one foot deep, 5 to 10 feet away from the parent plant. Pulling the suckers didn't help as it detach easily from the rhizome and quickly grows a new shoot from the 1/2 to one inch thick rhizome. Even trying to compost the rhizome and it will try to spread.

In zone 4 the seeds won't germinate for me. That's a good thing. I don't understand why but a few species which normally seed themselves in warmer zones have seeds that are more vulnerable to winter cold than the parent plant that the seeds form.


On May 5, 2009, giftgas from Everson, WA (Zone 7b) wrote:

Grows quickly vertically, but spreads very slowly compared to Japanese, Bohemian, or Himalayan knotweed.

When I say "slowly", I mean that the average person would be alarmed by the speed of the spread, but for the invasive plant lover, it's not that big of a deal.

This plant will eventually get large fantastic looking leaves about the size of a keyboard, with stalks about to 18' high.

It DOES have perfect flowers though, so unwanted seedlings might be a problem, thus being said, if you are the lazy type, you probably don't want to plant this in your yard for obvious reasons.


On Dec 28, 2007, lithophile from Hamden, NY wrote:

Extremely invasive, kills everything else, almost impossible to eradicate