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Blanket Weed

My pond was built in July so still early on but it has blanket weed!!  Horrible stuff!!  I have got 2 straw bales and 2 pots of oyster shell in the pond but it dosnt seem to have done anything.  Does it die back in the winter?  How do I get rid of it and why have I got it in the pond?  Someone said to me if I put a fountain in the pond it would get the water moving and that would get rid of it?  Is this true?



  • Caz WCaz W Posts: 1,353

    I think its best to try and first remove as much as you can by putting a long stick in the pond and twisting the blanket weed around it before using the straw bales.

  • artjakartjak Posts: 4,167

    My farmer neighbours built a pond this summer; it does have a pump and a waterfall but they swear by a barley bale quite small, about the size of a shoe box and their pond is very clear. They have just put netting over it to protect it from leaves (and herons!)

  • Yes I do use a bamboo stick to pull it out.  Its about 3m x 1.5 m and I put 2 of those barley straw things in.  Maybe it just takes time for them to work....

  • Time is what is needed, time for the proper plants to get a hold and deal with the excess nutrients that is helping the algae to take a hold. Algae needs light, heat and nutrients (nitrate and phosphate) to grow. If your pond is less than say 2ft deep it will heat up quickly in the summer, which helps the algae take hold quicker than the beneficial plants. if there are not enough oxygenators in the pond, which help alongwith the ordinary plants, take out the excess nutrients in the pond, you'll need to add more, probably next spring now. A good marginal plant to have in the pond, is Typha Minima, as due to it being a Dwarf Reed, it will do the job that large reeds do in natural pond filters in house water purifification systems, but without the size problems these big plants bring. Light can be reduced by floating plants or the obvious Water Lilies and if possible aim to have a third to two thirds coverage. I've moved house a few times and one year I tried an experiment in a small pond I built. In the first year, I introduced Duck weed to give me really good cover while the lily was growing and for the 2/3 years I was there, I never had any blanketweed to speak of. Word of warning though, Duck weed is extremely invasive and after it had done it's 'job' I had to get rid of it and that meant every single leaf, which was quite a job I an tell you.

    Blanketweed can be reduced to a manageable level quite quickly usual normal (already mentioned) ways, but that balance of plants can take months or in extreme cases, even years, but patience is all that is needed.

    Hope this helps a bit, but whatever you do, try not to resort to chemicals, as it would only be a short term solution and will affect beneficial plants you want to do well.

  • Thank you so much madonbirds.  Very informative.  No I will not be using any chemicals as I want a nature pond.  I have 2 small water lily plants in there so I suppose in time they will give the cover needed.  I put in several oxygenating and marginal plants.  Everything seems to be dying back now.  Is this normal?  So there wont be an cover during the winter?  It is about 60cm at its deepest point and then it has quite a large shelf all the way round that is about 20cm and then a pebbley area for animals to crawl out.

  • Joy HJoy H Posts: 6

    Hi, No need to worry about the plants dying back in winter because winter gives us shorter daylight hours and colder water conditions, so you don't need so much cover.  Our pond is always at its clearest during the winter, especially after frost. Good luck.


  • As Joy says, you don't need the cover in the winter, as like I said before about the three things you need heat light and nutrients. The heat and light isn't there during the winter, so algae like plants, won't be actively growing. Only thing to guard against in winter, is cut down the marginals and any decaying matter, like old lily leaves and flowers if you got any this year. In time, you will have to thin the oxygenating plants in autumn, but they'll still be manageable this year.

    Just be patient and you will soon have a great pond, maybe the odd bit of algae, but even that can be beneficial to certain wildlife in the pond. Have fun, just wish everyone would build a pond.

  • Thank you.  It is lovely having a pond in the garden.  Theres something very realaxing about water.  I had a few damelflies in the summer and I could see all these organisms swimming around in the water.  Dont know what they were.  There were a few small black snails that I presume came in on the pond plants I brought but havnt seen them for a while.  Do the snails and organisms go to the bottom of the pond when it starts getting colder?  Cant wait for frogs and toads to find it. image


  • Sorry Christy, didn't get the email message to say you'd replied like last times!!

    Snails I believe, go into a sort of semi hibernation where they slow their heart down in the coldest of weather and stay in their 'house'. Snails will always exist in ponds and are a good thing, clearing away rotting vegetation. Only wildlife you don't really want is the great diving beetle.

    Try and not bring in frogspawn, as it's always best to allow them to find it first, it means your pond is right for them. Two gardens ago, I had put in a small tub pond buried to keep some plants, while I built the big one and within two days I had two frogs! They still spawned in the big one, which had fish in it, each year we were there from the following year onwards. Some always survived to spend time in the garden and do the good work they do there.

  • Sorry Madonbirds,  I didnt get your last message - dont know whats going on here.  Just had to tell you that I went out the other night to shut the chickens coop up and I shone the torch into the deepest part of the pond and there was a toad there!!  Fingers crossed for the spring!!

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