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Invasive grass around pond margin
nicky29
Posts: 10
Any suggestions for getting rid of this grass - it is rooted through a liner that is probably over 20 year old. Roundup - used with care has been suggested. What damage likely for pond life - fish, tadpoles, various wriggly things, lilies, oxygenation plant? Any other options? Chemical or otherwise? Ripping out and replacing the liner and starting over will probably be prohibitively expensive.
Many thanks
0
Posts
if it has rooted through the liner the liner will be leaking and need replacing anyway, despite the cost I would rip out over winter and start again.
Can you post a closer photo of the pond and the vegetation round the edge? Hard to tell for sure but looks rather more like the sedge Cyperus longus (galingale) than a grass. To be honest if the pond is holding water OK than I wouldn't be in too much of a hurry to do anything too drastic. Personally I'd probably just cut a gap or two round the edge so you can see the pond and leave the rest. A hand scythe would be ideal for the purpose, or else a strimmer, but I'd be fairly conservative with the cutting.
I would be concerned about using any chemicals that close to the pond. Even tiny amounts of some garden chemicals can be lethal to fish. I would be inclined just to use a strimmer to clear the grass from the side nearer the house, and leave that at the back.
Thank you to all who have responded so far. The pond appears to hold water and considering how dry it has been recently is at a good level. I suspect any roots through the liner are slowly expanding and keeping a nice tight waterproof fit (bit like the airtight fit of the hawthorn thorn in the lawnmower tyre!).
Over the last couple of years, we have been strimming it right down, and then keeping some gaps repeat strimmed to enable a view across e.g. to the gunners, but that seems to make it grow all the more! It really is a thug. One pond person was surprised that it has beaten the iris there which can also be invasive and thug like but not on this occasion.
I am not local to the pond (it's my Mothers), I have cropped and blown up a corner the picture, so hope the quality hasn't degraded too much, which might aid identification.
One suggestion has been to drain the pond (fish and weed/lillies etc. in a holding tank), remove any sludge that might be encouraging growth, strip, then weed kill, then wash down the liner and re-pump out, then black wrap, then put it all back together again.
But what would you do about the holes?
Are you sure that the grass has pierced the liner and isn't just spreading across the surface and rooting down into the sludge?
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
Yes, definitely Cyperus longus. Personally I find it quite attractive. Apparently it doesn't set seed in this country so spread and regrowth will just be from the rhizomes.
I don't have a better suggestion than cutting down sections though - I think a complete pond renovation would probably be more trouble than it's worth since it's still holding water OK.
I had a similar problem with a pond. I don't know what the 'grass' was which grew through the liner, it was triangular in cross section. It grew through a thick butyl liner, but fortunately was self-sealing and I lost very little water through leakage.
That one looks like a large pond and the work and cost of replacing the liner would make the job a near impossibility without getting professional help in.
If / when the worst comes to the worst, and work has to be done, I would be inclined to firstly remove the fish, plants and crud in the bottom. Then try to find the edge of the liner, lift it back and remove as much growth from below as possible. Finally overlay the existing liner with a new one. Absolutely no point in removing the existing one.
... other than to get rid of the 'grass roots' which, having penetrated the first liner will probably penetrate the new one
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.