Please help me with identification of this green-brown mass in my garden. It looks rather like slimy, part-rotted fruit, but I have noticed it under roses in both spring and autumn.

Is it a weed or what? Do I need to worry about it (it seems to be choking the primulas I have in the same bed)? Can it go in the compost bin?

The location is England.

Slimy green-brown mass.

1 Answer 1


It's Nostoc, a type of cyanobacteria - it often occurs in lawns, sometimes in borders, but it's not particularly harmful, in fact it fixes nitrogen, which is good for your plants, despite its rather disgusting appearance. You probably notice it in spring and autumn because that's when the soil's wet enough and temperatures are right for it to be visible, it likes cool, damp weather, which tends to occur at those times of year. Rather than just being one organism, it's actually a collection of cyanobacteria - you're unlikely to be able to get rid of it completely, though you could try clearing some of it away from your primulas. Info here http://askanaturalist.com/what-is-this-green-jelly-slime-in-my-garden/

Not sure I'd put it in the compost bin - I'd be inclined to bag it and bin it. In the compost bin might mean, when you eventually use the compost in the garden, it pops up all over the place in similar weather conditions.

  • The 'cold, wet weather' comment is certainly accurate. It has largely vanished after some dry days.
    – Peter Bill
    Commented Apr 15, 2018 at 16:15
  • Agree that mixing in compost is not a good idea. This stuff is indestructible, and doesn’t need your help to proliferate.
    – bubba
    Commented Dec 5, 2022 at 1:35

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