Wednesday, 19 September 2012

We must talk about...blanketweed


...and newts!


To many gardeners, it’s the green scum that needs to be regularly dragged out of the water with a thin tined lawn rake. To us, it is a haven for wildlife, providing both habitat and nutrition for a wide variety of insects and amphibians. 

Blanketweed is a filamentous algae whose new growth arises from the depths each sunny morning glistening with purifying bubbles of oxygen. We love watching baby frogs hopping on the green surface carpet and on to the water lilies and water soldiers. 

Blanket weed ‘sucks’ unwanted nutrients from the water including all those nitrates when we top up with tap water. As a result the pond water is crystal clear.

Rather unwittingly, we have created ideal conditions for crested newts. My no-dig methods, along with the use of glyphosate, leave a rich weed free vegetation and liverwort, pearlwort and moss encrusted surfaces. 

My favourite sandstone mulching and edging stones are loosely bound together by liverwort and provide places where newts might hibernate. The herons have made their own contribution. We have no fish!

Water snails love the blanket weed, and their general scavenging helps keep the pond clear. It’s fascinating watching them feed.
Newts like a land habitat too.
For most of their lifecycle newts need open fields and cover. They move seamlessly between the farm fields, my unfenced garden and the big, unlined breeding pond next door. In August the newts will have been feeding amongst the blanket weed. It would have been cruel and foolish to skim it away! Now in September, it is safer and I will drag out bundles of blanket weed, excess oxygenating plants and Autumn leaves. 

It is absolutely essential to avoid too much vegetation which, if allowed to decay, deoxygenates water. None of my nine ponds have any filters or pumped circulation.

When I drag out surplus vegetation I do not waste all that lovely organic matter It is left at the side of the pond touching the water. This allows fauna to return to the pond. I throw back the snails. My debris is later ‘lost’ behind plants or goes on my vegetable garden. Most of you will sensibly put it on the compost heap.

I have a dilemma! Rare Great Crested Newts bring such a responsibility! Last summer, brother-in-law Dave built me a beautiful stack of drying logs. It must make a wonderful newt hibernacle. Perhaps the logs will never be burnt!

(above: juvenile Great Crested Newt eft) Great Crested Newts move in and out of breeding ponds, as well as between ponds, over spring and summer. Most will have left the water by August and emigration from the pond usually coincides with periods of rainfall. Most newts are dormant by the end of November. A good overwintering site may be a void in a tree stump or bank, or under refugia such as rock piles or dead wood. Juvenile newts are known to emerge from ponds around August and September, and there is some evidence that they recognise and follow the scent trails of the adults to find high quality foraging habitat and refuge. For successful emergence, ponds should retain water and be left undisturbed until at least the end of August. 

18 comments:

  1. Interesting post Roger, I have learned something today.

    ReplyDelete
  2. Blanket weed is a symptom of pollution which comes from tap water so to make your garden pond better for wildlife start off with the cleanest water - rain collect in water butts and refill your ponds with rainwater rather than potentially really polluted water from the tap.....

    ReplyDelete
    Replies
    1. Thanks for your helpful comments Jon.
      Unfortunately on my windy site, without tap water I would have no ponds. As mentioned in my blog I do not dislike blanketweed, it helps keep the water clear. It is easily removed when in excess with my trusty lawn rake. I do not regard my pond as polluted even though tap water does contain nitrate, quite a lot actually.
      My neighbour's large natural pond which never sees tap water or receives farmer's fertiliser is full of blanket weed. This pond is probably loaded with nitrate from the numerous birds and their droppings. Similarly I would suggest water collected from roofs is also rich in nitrate from bird droppings.
      Had a look at your interesting blog, Jon.

      Delete
    2. Nitrates are not the best stuff in the world but I'd hesitate to call it 'pollution'. We have blanketweed at certain times of the year (usually midsummer) in our big, natural wildlife pond. We don't even bother to rake it out because it's always heaving with GCN. The young newt fry use it as cover from predators. As far as I'm concerned, a bit of blanketweed is good for all sorts of pond fauna.

      Delete
    3. You are so right. It's habitat.

      Delete
  3. Blanket Weed is a pain for most Koi pond keepers, but like your post says it sucks up nutrients really well so why not enhance it's power and grow it in an area of your pond under control or maybe build an open top filter to allow it to grow in full sunlight. Marine hobbyists do something very similar in sump filters and the results are very good.

    Holiday Aquatics

    ReplyDelete
    Replies
    1. Thanks for the instructive advert. My ponds are primitive and I don't do filters - except my plants do it for me

      Delete
  4. Hi Roger, I really like your blog it was awesome I really get some new thing to learn. As blanketweed problem is a big headache to get rid off. I have seen a video on YouTube is which it showing a product which easily and rapidly removing blanketweed and also helps to prevent it. I think you should watch that video .It was amazing product..

    Link : https://www.youtube.com/watch?v=K3IWawhWYR4

    ReplyDelete
    Replies
    1. Thanks for your link. I see they call their weedkiller 'treatment' although I am the last person to condemn such herbicides!

      Delete
  5. Blanket weed is a natural occurrence, and not a dysfunction. It is the habitat for newts and tadpoles. I leave it alone for the summer, as Roger does. Sometimes I push it to one side, or to a shady area of the pond, as the animals can swim to the light, but shades limits its growth. You can't have wildlife without blanket weed.

    ReplyDelete
    Replies
    1. Thanks unknown for coming to my aid

      Delete
  6. If you take blanket weed out of the pond and leave it to one side, most of the creatures will die. During tadpole and newt fry season, it is better to push it to one side of the pond. If you have more water lilies and water soldiers, but as Roger points out, blanket weed is valuable habitat.

    ReplyDelete
    Replies
    1. A very good tip Anne.Marie. its about time I wrote another post about ponds!

      Delete
  7. One thing that did help control blanket weed: I planted native UK watercress seeds right on top of it. It grows very well, and looks very pretty, and the cress clears the water, while keeping a small island of blanket weed, enough for the newts. I later added regular land cress, and also water mint, and it also grows hydroponically. Frogs love the little islands, and bees and butterflies use them as safe places to land and get moisture. The cress looks a bit like a little chia pet. I tried this because I felt like potted pond plants were bringing in more nutrients. I also plant water lilies with no pots, just sinking the rhizome with a weight made out of a broken terra cotta pot, and the water lilies that are not potted bloom more than the ones I bought planted in compost. We've had scores of common froglets and toadlets this year, and I'm determined not to disturb the newtlets by pulling out the blanket weed. As it is, the weed is shrinking on its own, now that the froglets have left the pond, because their waste must have added nutrients.

    ReplyDelete
    Replies
    1. It sounds fascinating. I love to hear from gardeners who innovate and try new things.
      My own blanket weed is almost history and generous plant cover of my general planting now sucks out the nutrients. My latest post (on tomorrow 15 July 2018) has a recent picture if you scroll down.
      Water cress sounds interesting, blogger Sue Garrett who often comments grows this
      I'm afraid we use tap water to replace water evaporated away and unfortunately this adds extra nutrients. I occasionally fish out duckweed and tangled blanket weed with my plastic scarifier. Afraid I am not into instagrm. I would love to see at picture via nodiggardener@gmail.com
      All my plants have now grown out of their original pots

      Delete
  8. I'm on instagram @theladyingolden if you want to see photos of my pond strategies.

    ReplyDelete
  9. The water cress looks prettier than the blanket weed it grows on. Its roots help to suck nitrates out of the water. I wish I had learned this trick before. Next spring I'll start planting my floating islands of blanket weed as soon as the tadpoles make me reluctant to remove it.

    ReplyDelete
  10. We also use tap water, especially with the heat wave and the drought. We have no fish. But the robust population of toads and newts created a lot of waste, and clouds of blanket weed hung over the places they clustered. But once they left, the blanket weed started to disappear on its own. Every day the pond is clearer. I'll send you some pics of the newtlets lounging around in the blanket weed that remains.

    ReplyDelete

Related Posts Plugin for WordPress, Blogger...