I have wildflower seeds to spread on a patch of unused ground. To give them more of an edge I want to weed kill first with standard glycophosphate home weedkiller.

How long if at all should I wait after applying to sprinkle seeds?

1 Answer 1


If you mean glyphosate or Round Up, unless you have weeds actively growing, it won't do anything because it 'kills through the green', it doesn't prevent germination. Even if you have weeds present, most might be killed with one application, some won't, and further germination is likely, depending on which weeds you have.

I believe the packaging says how long you should wait to sow seeds, and it probably says something like three days, although it can take up to 14 days for the treated weeds to die back fully, so sowing seed that soon can be difficult if the area is covered in slowly dying weeds.

  • Yeah there are some weeds and I want to give the new seeds a fair chance. I can't stop existing seeds germinating - though I think most will have already - but all I want is to ensure my seeds are not harmed by the chemicals.
    – Mr. Boy
    Commented Jun 5, 2021 at 14:25
  • Personally, I'd wait till the existing weeds had died back, so between 7-14 days.
    – Bamboo
    Commented Jun 5, 2021 at 15:54
  • There's also an herbicide called glufosinate. But, like glyphosate, it has no residual activity in the soil and won't have any effect on seeds.
    – csk
    Commented Jun 5, 2021 at 15:56

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