Japanese Knotweed on the move again!


Japanese Knotweed Growth

The sunny weather in March following a strangely mild February in 2011 means that Japanese Knotweed is on the move again – weeks earlier than last year. The rhubarb-like leaves of this year’s new growth of Japanese Knotweed (JKW) plants are shooting up from the ground all over the UK.

For those who do not know what Japanese Knotweed is like, see the picture so that you can spot the first stirrings of this very unpleasant and invasive plant. The photo was taken in the North of England last week

Now is the perfect time to see if you have JKW in your garden or, almost as bad, whether your neighbour has some growing near your fence or land. Become a plant detective so that you can for prepare battle against the Knotweed – but just not quite yet.

The most cost-effective way to fight Japanese Knotweed is to spray it with herbicide over a period of three years, if you have the luxury of time. It can be killed in a year but the nasty effects of the very strong chemicals needed to do so in this short time-frame may have dire implications for any other plants, tress or bushes nearby.

The best time to start to tackle the weed is once the plant has developed a good leaf structure – usually in May. And since it can grow inches a week, it will not be long before treatment can begin.

On no account try to dig it up as some many homeowners do. All this does is break-up the rhizomes of the plant and it spreads quicker than ever.

It can be dug up, of course, but large machinery is usually employed by the Japanese Knotweed contractor. The roots or rhizomes of the JKW can go down many feet in search of water. We had to excavate down 12 feet on one building site we worked at last summer and we often find roots eight feet below the surface of the ground. Digging it up and hauling the contaminated soil away to landfill is a very expensive undertaking. The cost is inflated by the Government’s very high Landfill Tax as well as hiring a small fleet of lorries to remove the soil.

Whenever possible and if time allows, spray Japanese Knotweed with herbicide. It works but it is certainly no instant solution.