[mrs bouquet]

Two things, the first is low growing brown ornamental grass, which is under matting and gravel, and is spreading everywhere.   The second is Cuckoo Pint (Lords and Ladies).  I have tried Roundup, and tipped a bottle of bleach on the grasses.
Somebody has suggested,  mixing salt, white vinegar and washing up liquid (The latter to make it stick to the leaves).    I am not really sure about this, I don't want to blow myself up  .   I thought I also heard somebody mention diluted quicksilver (that's mercury isn't it ?)   The grasses have nothing else growing near them, But the Lords and Ladies, are near ferns and lilly of the valley.   
Thanks for reading this, and all your comments and ideas will be much appreciated,    Mrs Bouqet

[RubyRed]

Blimey are they that much of a problem that you are prepared to poison the soil and yourself  (Mercury). Can't you just dig them out, or at least cut the seed pods of the cuckoo pint. They are lovely plants. Don't whatever you do touch mercury, and I've not heard it being able to be diluted anyway. It's a heavy metal.

[mrs bouquet]

The person who mentioned Mercury, has since come back and said he subsequently meant Silver Sand.
I said, erm, maybe, thanks.    I know I cannot hear, but I said to him, Quicksilver, that's Mercury isn't it.
He replied,   I don't know, is it ?   That's why I put it on the this thread to double check. 
The brown grasses, I have now sprayed with, salt, white vinegar and washing up liquid (smells like a chips shop), after cutting it back as much as possible, and then trying to break the centre of the plants.   I cannot dig it out at present, I have tried, but it is about 4ft square, and too much under the gravel and matting.
So I shall wait and see what happens.
The Lords and Ladies, I have dug a lot out, and left a smallish clump, it is pretty because it is verigated.
I shall be vigilant and remove the berries this autumn.  Mrs Bouquet

[snowdrops]

I would think if you cut them down as much as that Mrs B, exclude all light by covering in some manner, keeping an eye on it & should it regrow, cut it down again. Keep doing this for a year or 2 if necessary I’m sure that will kill it with out the need to risk dubious chemicals on it 😊