Another Japanese Knotweed fight

By | Species, weeds | No Comments

Japanese knotweed is a nasty invasive perennial plant which destroys habitats especially around water bodies. As soon as I found a patch at a far corner of my site, I was on high alert. The invader probably benefitted from soil disturbances as condominium construction happened on both sites.




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Japanese knotweed (Fallopia japonica)

This is bound to be huge headache because our site is on the right and nobody is maintaining the area on the left. Since knotweed spreads by roots this will be a constant fight. Knotweed roots can extend for 20m from the parent plant and 3m deep. Definitely call or click before you dig. I hope the landscape maintenance company next door takes action soon.




We didn’t have time to dig but we flush cut the hollow bamboo-like canes as close to the ground as possible. Some people are tempted to pour illegal substances on the stumps under cover of darkness. I know many municipalities use heavy chemicals that would be illegal for residents to apply. That’s how desperate it has become.


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One small clump generates lots of foliage and shade.




City of Coquitlam, BC. This is a common roadside problem. The city sprayed this patch to keep it in check and off the roadway.


Knotweed details

The flowers on knotweed are actually attractive. They are small, white and grow in showy, plume-like, branched clusters along the plant stem and leaf joints. How can you make sure you’re dealing with knotweed in the absence of flowers? Look for the zigzag pattern in which leaves are arranged along the plant stems.



Leaf and flower detail.


Knotweed isn’t the only bad boy invading our landscapes. There is a long list of others. Learn to recognize them and try to plant sound alternatives. Visit the Invasive Species Council of BC. They also have volunteer opportunities. But education is key.

Learning to recognize weeds is actually an important skill. New landscapers struggle in this department because machine use comes first. But once they do finesse-type work they need to recognize unwanted weeds from good plants. This takes time just like plant identification skills. Fortunately, there are only so many key weeds in our landscapes.

Weeds we fight: snapweed

By | weeds | No Comments

There are many native plants that are considered weeds in horticulture and one such plant is little Western bittercress (Cardamine oligosperma). It’s actually a nice little plant. But read on because you will soon find out why we fight this weed in our landscapes. I see it on all of our sites. The best procedure is to fight it before it flowers and produces seeds.



Flowers and upright siliques full of seeds



Cardamine oligosperma is a fast-growing native to Western North America. It’s an annual or biennial herb which grows from a taproot. It’s usually 20cm tall and grows in a branched form.

Flowers have four white petals 2-4 mm long.



Brownish colour indicates maturity and chances of explosions



Cardamine oligosperma fruit is a narrow exploding silique 1.5 mm wide with 15-22 seeds. Seeds are oblong-ovate and they are the plant’s mode of propagation. This is great information for landscapers.

Another common name for this plant is snapweed. This is because when the siliques mature they explode. You can touch them and have some fun with exploding seeds. Just don’t do it on my sites. Remember what we do with weeds: we get to them before they flower or worse, produce seeds.

I had some fun today. I ran my fingers over a mature Cardamine oligosperma and tried to catch as many exploding seeds as I could. The photo below shows the result. Now imagine if you let a patch of snapweed mature and explode seeds all over your landscape. You are looking at a fight next season. So get to them before they mature.




One silique and seeds in my landscaper hand


In conclusion, get to know little Western bittercress or snapweed (Cardamine oligosperma) and fight it in your landscapes. It might be a cute native herb but we can’t let it produce seeds on our sites.