Spring was warmer than usual this year - as you no doubt noticed if you spent it cooped up at home due to the COVID-19 (coronavirus) pandemic.
Unfortunately, a warmer-than-average spring means that there'll probably be a lot of Japanese knotweed this summer.
READ MORE: When Does Japanese Knotweed Grow?
Summer is peak growing season for Japanese knotweed, although its first shoots start to appear around April. The first half of this year may have been a chaotic and disruptive period from our human point of view, but spring 2020 brought ideal growing conditions for Japanese knotweed, with plenty of warm weather and sunshine.
As its name suggests, Japanese knotweed (Fallopia japonica) is native to the Far East. Once upon a time, this plant was to be found only in Japan and neighbouring territories like Korea and China.
Now, as we've previously discussed, Japanese knotweed wasn't - and still isn't - much of a problem in its homeland, simply because the local ecosystem keeps the plant in check.
But at some point, somebody had the bright idea of bringing Japanese knotweed over to Europe, where it was able to run rampant and cause all kinds of problems for us Westerners.
Read More: What Damage Can Japanese Knotweed Do?
This raises the question: just who do we blame for bringing Japanese knotweed to Europe?
Japanese knotweed causes a lot of problems in the UK, but you might be surprised to learn that this invasive species is NOT notifiable.
This means that, if you find Japanese knotweed in your garden, you are NOT legally required to notify the authorities. It is not an offence to have Japanese knotweed on your property as long as you are not allowing it to spread.
Bleach is a household cleaning product that's great for killing germs in the bathroom - but it shouldn't be used to kill weeds.
If you've got Japanese knotweed on your property, you probably don't need us to tell you how difficult this invasive species is to get rid of. Knotweed is infuriatingly resilient; supermarket weedkillers tend to be ineffective, so your only real options are excavation or long-term control with specialist herbicides.
Japanese knotweed causes a lot of problems here in the UK. It grows very quickly, it's difficult to get rid of, and it can cause structural damage by growing through small cracks in buildings. Properties with Japanese knotweed are difficult to sell, and worst of all, if you allow this invasive species to spread, you can be fined or sent to prison.
Still, if Japanese knotweed is capable of making life so difficult for us Brits, just think of how much chaos the plant must cause back home in its native Japan! Right?
Well, actually, no - Japanese knotweed isn't a big problem in Japan at all. Over there, it's just another plant.
COVID-19 (coronavirus) remains the UK's public enemy number one, and while lockdown measures have started to relax in England, they're still in full effect here in Wales. The Welsh government are currently advising people to:
- Stay at home
- Go out for food, work and health reasons only
- Work from home if possible
- Stay 2 metres from other people
- Wash your hands immediately when you get home
If you have a garden, it's probably getting a lot of use right now - after all, spring is in the air, and if you want to enjoy the longer days and get a bit of fresh air, your own back garden is the safest place to do so!
But what if, while you're soaking up the sunshine, you spot Japanese knotweed shoots emerging from your soil?
Japanese knotweed has a reputation for rapid growth, but this invasive plant's growth rate does peak and trough over the course of a year.
The growing cycle can vary somewhat depending on what the weather's doing, but there is a reasonably consistent annual pattern. Here's a rough timeline of Japanese knotweed's growing behaviour from one season to the next.
For reasons discussed in our DIY Japanese Knotweed Removal blog post, we DO NOT RECOMMEND attempting to get rid of Japanese knotweed on your own. Instead, get in touch with a specialist contractor who knows how to deal with this invasive species and ensure that it does not spread elsewhere.
Photo by dankogreen (Flickr)
Broadly speaking, there are two ways to kill Japanese knotweed:
- Herbicides - spraying the plant with weed killer
- Excavation - digging the plant up and either burying it or safely disposing of it at an approved landfill site
Japanese knotweed has a durable rhizome root system that can be very difficult to completely eradicate.
Rhizomes - sometimes known as creeping rootstalks - are like plant stems that run horizontally through the soil. Roots and shoots grow out of the rhizome's nodes to seek nourishment as the plant grows.
Few plants inspire as much dread as Japanese knotweed. This invasive species can make it difficult to sell your house, and even if you get rid of it, there's a chance the plant will grow back again if there's so much as a single fragment still in the soil.
Another oft-cited reason to fear Japanese knotweed is the damage it can cause as it grows in search of moisture and nourishment. Some descriptions would have you believe that Japanese knotweed is a rampaging triffid-esque plant monster, capable of demolishing any structure that gets in its way.
Well, you can rest assured that Japanese knotweed won't be knocking over any buildings in the near future. What it can do is exploit existing weaknesses in a structure - for instance, we often see Japanese knotweed growing through cracks in brick walls and concrete paving.
Photo by Gordon Joly