I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front garden in question won't have anything done to it for a year, so
it would be a convenient time to cover it and treat any shoots appearing
at the edges. There is thick concrete either side, so with luck it won't
find its way past that. However, I don't want to create a damp
hothouse environment that might make matters worse over the summer. Any
advice appreciated

"Stuart Noble" wrote in message
m...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The front
garden in question won't have anything done to it for a year, so it would
be a convenient time to cover it and treat any shoots appearing at the
edges. There is thick concrete either side, so with luck it won't find its
way past that. However, I don't want to create a damp hothouse environment
that might make matters worse over the summer. Any advice appreciated

As it can push its way up through tarmac, I can't see plastic sheeting being
an effective barrier. And thick concrete won't be a barrier unless it goes
down several metres.

You can try repeated applications of glyphosate, especially as you say it
won't have anything done to it for a year. Other possibilities include the
path weed suppressants (most of which have been removed from the market),
but in my experience they weren't as effective as glyphosate. There are
some products around such as Weedol Rootkill Plus or Bayer Path Weedkiller
which might be more effective. Or you could try Sodium Chlorate.

Good luck!

--

Jeff

In article ,
says...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front garden in question won't have anything done to it for a year, so
it would be a convenient time to cover it and treat any shoots appearing
at the edges. There is thick concrete either side, so with luck it won't
find its way past that. However, I don't want to create a damp
hothouse environment that might make matters worse over the summer. Any
advice appreciated

Repeated applications of Glysophate are your best bet, the NT cut the
stems during its growing season and squirt glysophate down the hollow
stems, there are web sites where information and advice can be found but
I fortunately do not have this problem.
Plastic sheet would last less than a week and it would be through, I have
seen it come up in the middle of roads and through 3" of concrete.
I have seen some reports of mowing it twice a week weakening it but have
wondered what you do with the mowings as its an offence to dispose of any
part of the plant without a licence!
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea

Stuart Noble wrote:
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front garden in question won't have anything done to it for a year, so
it would be a convenient time to cover it and treat any shoots
appearing at the edges. There is thick concrete either side, so with
luck it won't find its way past that. However, I don't want to create
a damp hothouse environment that might make matters worse over the
summer. Any advice appreciated
It's been known to cross underneath tarmac roads so I understand.
Good Luck
Don

On Mon, 15 Feb 2010 09:41:28 -0000, Stuart Noble
wrote:

I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front garden in question won't have anything done to it for a year, so
it would be a convenient time to cover it and treat any shoots appearing
at the edges. There is thick concrete either side, so with luck it won't
find its way past that. However, I don't want to create a damp
hothouse environment that might make matters worse over the summer. Any
advice appreciated


It may be worth your while having a look at the advice on
http://www.cornwall.gov.uk/default.aspx?page=13803

--
rbel

"Stuart Noble" wrote in message
m...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The front
garden in question won't have anything done to it for a year, so it would
be a convenient time to cover it and treat any shoots appearing at the
edges. There is thick concrete either side, so with luck it won't find its
way past that. However, I don't want to create a damp hothouse environment
that might make matters worse over the summer. Any advice appreciated


Hi Stuart,

When we moved to this house and garden nearly 30 years ago, there were two
or three stands of Japenese Knotweed. At that time, I didn't know what it
was, just that it was a menace. We called it Doomweed then, and still do!

I spent a couple of years doing nothing in the garden but digging it out ..
waiting for it to reappear .. digging it out ... Eventually, I got to the
point where it was considerably weakened, but some furled red shoots still
appeared. Whilst in this weakened state, we liberally blasted it with
glyphosate, firstly as directed, then neat. We got rid of it! :~). There
is no really effective way of eradicating it, except blood, sweat and tears
followed by Glyphosate. If it's in your neighbour's garden too and they're
not willing to shift it, then I'm afraid you're doomed. Moving house is
probably easier :~(.

Alas, I have noticed a huge stand of Jap. Knotweed in my rear neighbour's
garden. I'm watching it very, very carefully. *Gulp* :~(


--
Spider
from high ground in SE London,
gardening on clay.

In article , lid
says...
"Stuart Noble" wrote in message
m...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The front
garden in question won't have anything done to it for a year, so it would
be a convenient time to cover it and treat any shoots appearing at the
edges. There is thick concrete either side, so with luck it won't find its
way past that. However, I don't want to create a damp hothouse environment
that might make matters worse over the summer. Any advice appreciated


Hi Stuart,

When we moved to this house and garden nearly 30 years ago, there were two
or three stands of Japenese Knotweed. At that time, I didn't know what it
was, just that it was a menace. We called it Doomweed then, and still do!

I spent a couple of years doing nothing in the garden but digging it out ..
waiting for it to reappear .. digging it out ... Eventually, I got to the
point where it was considerably weakened, but some furled red shoots still
appeared. Whilst in this weakened state, we liberally blasted it with
glyphosate, firstly as directed, then neat. We got rid of it! :~). There
is no really effective way of eradicating it, except blood, sweat and tears
followed by Glyphosate. If it's in your neighbour's garden too and they're
not willing to shift it, then I'm afraid you're doomed. Moving house is
probably easier :~(.

Alas, I have noticed a huge stand of Jap. Knotweed in my rear neighbour's
garden. I'm watching it very, very carefully. *Gulp* :~(



It is now an offence to do nothing about it so if you like your
neighbours point that out tactfully, if you don't like them drop them in
it with Defra!

--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea

"Charlie Pridham" wrote in message
T...
In article , lid
says...
"Stuart Noble" wrote in message
m...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front
garden in question won't have anything done to it for a year, so it
would
be a convenient time to cover it and treat any shoots appearing at the
edges. There is thick concrete either side, so with luck it won't find
its
way past that. However, I don't want to create a damp hothouse
environment
that might make matters worse over the summer. Any advice appreciated

Hi Stuart,

When we moved to this house and garden nearly 30 years ago, there were
two
or three stands of Japenese Knotweed. At that time, I didn't know what
it
was, just that it was a menace. We called it Doomweed then, and still
do!

I spent a couple of years doing nothing in the garden but digging it out
..
waiting for it to reappear .. digging it out ... Eventually, I got to
the
point where it was considerably weakened, but some furled red shoots
still
appeared. Whilst in this weakened state, we liberally blasted it with
glyphosate, firstly as directed, then neat. We got rid of it! :~).
There
is no really effective way of eradicating it, except blood, sweat and
tears
followed by Glyphosate. If it's in your neighbour's garden too and
they're
not willing to shift it, then I'm afraid you're doomed. Moving house is
probably easier :~(.

Alas, I have noticed a huge stand of Jap. Knotweed in my rear neighbour's
garden. I'm watching it very, very carefully. *Gulp* :~(


It is now an offence to do nothing about it so if you like your
neighbours point that out tactfully, if you don't like them drop them in
it with Defra!

--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea


Could be interesting! One of those neighbours may be the local council, as
well as one or two residents. The council certainly ought to know better;
more importantly, they ought to know the law! I'll have to investigate who
owns what ...

Thanks, Charlie.

Spider

"Charlie Pridham" wrote ...
says...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front garden in question won't have anything done to it for a year, so
it would be a convenient time to cover it and treat any shoots appearing
at the edges. There is thick concrete either side, so with luck it won't
find its way past that. However, I don't want to create a damp
hothouse environment that might make matters worse over the summer. Any
advice appreciated

Repeated applications of Glysophate are your best bet, the NT cut the
stems during its growing season and squirt glysophate down the hollow
stems, there are web sites where information and advice can be found but
I fortunately do not have this problem.
Plastic sheet would last less than a week and it would be through, I have
seen it come up in the middle of roads and through 3" of concrete.
I have seen some reports of mowing it twice a week weakening it but have
wondered what you do with the mowings as its an offence to dispose of any
part of the plant without a licence!

I've seen articles saying the young 8 inch shoots are edible and delicious,
like Rhubarb but better, and that if you keep cutting them off so the plant
cannot photosynthesise it eventually dies. How long that takes is anyone's
guess.
Personally I would use the Glyphosate down the cut stem method to kill those
deep roots and dry and burn the cut stems.

--
Regards
Bob Hobden
W.of London. UK

On Mon, 15 Feb 2010 20:04:10 -0000, Stuart Noble
wrote:

Thanks everybody. The plastic sheet idea doesn't sound promising then,
but I might try a damp course membrane weighted down with paving slabs.
I would guess there are always weaknesses in concrete and tarmac, and
maybe the uniformity of the polythene would make a difference. I'd
probably be doing this anyway to discourage normal weeds, so there's
nothing lost if it doesn't work.

Stuart, if as you said in your first post you are going to leave the
garden for a year, you really do need to do something about the knotweed
*before* you cover it.
If you don't, the infestation will be worse, much worse in a year's time.
Even if the shoots do not manage to pierce the membrane, the roots will
continue to multiply both directly under the garden and sideways beneath
the surounding concrete areas. Knotweed has even been known to bury under
house foundations and come up through the floor inside.
You should listen to the advice about applying a generous dose of
glyphosate.

In article ,
lid says...

"Spider" wrote in message
...
"Charlie Pridham" wrote in message
T...
In article , lid
says...
"Stuart Noble" wrote in message
m...
I've read everything I can find online about Japanese Knotweed but I
wonder how effective plastic sheeting might be in smothering it. The
front
garden in question won't have anything done to it for a year, so it
would
be a convenient time to cover it and treat any shoots appearing at the
edges. There is thick concrete either side, so with luck it won't find
its
way past that. However, I don't want to create a damp hothouse
environment
that might make matters worse over the summer. Any advice appreciated

Hi Stuart,

When we moved to this house and garden nearly 30 years ago, there were
two
or three stands of Japenese Knotweed. At that time, I didn't know what
it
was, just that it was a menace. We called it Doomweed then, and still
do!

I spent a couple of years doing nothing in the garden but digging it out
..
waiting for it to reappear .. digging it out ... Eventually, I got to
the
point where it was considerably weakened, but some furled red shoots
still
appeared. Whilst in this weakened state, we liberally blasted it with
glyphosate, firstly as directed, then neat. We got rid of it! :~).
There
is no really effective way of eradicating it, except blood, sweat and
tears
followed by Glyphosate. If it's in your neighbour's garden too and
they're
not willing to shift it, then I'm afraid you're doomed. Moving house is
probably easier :~(.

Alas, I have noticed a huge stand of Jap. Knotweed in my rear
neighbour's
garden. I'm watching it very, very carefully. *Gulp* :~(

Indeed and down here when I was growing up it was known as Donkey Rhubarb
and we all ate it as children, My wife still maintains the only reason it
has become a problem as children don't eat it any more!!
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea

I've seen articles saying the young 8 inch shoots are edible and delicious,
like Rhubarb but better,...................

Personally I would use the Glyphosate

If it's like Rhubarb then I'd use custard on it.
David Hill

Dave Hill wrote:

Sorry we bothered, next time we'll keep quiet.

I don't object to being reminded about something I might have missed
(although that would be difficult when googling knotweed), but I don't
expect to be reprimanded for daring to suggest a supplementary approach.

" I've seen articles saying the young 8 inch shoots are edible and
delicious,
like Rhubarb but better, --
Regards
Bob Hobden
W.of London. UK



During the war, we as kids, would play in the jungle of Knotweed and often
chew the stems - as you say like rhubarb but quite sharp. They would be
thirst quenching. as kids we'd try anything.

I can't say how the stems would be used in the kitchen though.

Bill

Charlie Pridham wrote:

Indeed and down here when I was growing up it was known as Donkey Rhubarb
and we all ate it as children, My wife still maintains the only reason it
has become a problem as children don't eat it any more!!

I don't know if anyone's mentioned this as I've passed-over a lot of
posts due to lack of snipping -

but, heard on Auntie BBC there is, there is about to be or there has
been a trial with a (Japanese) insect which noshes knotweed to death.

--
Rusty