By Patfran
Leicestershire,
United Kingdom 
I moved house 18 months ago and never use chemicals. I don't know about the previous owners so how long will it take for my garden to be chemical free if they used things like weed killer or black spot spray etc.?
6 Feb, 2019
Answers
I think that organic certification organisations say two years.
7 Feb, 2019
Your garden will never be chemical free. Everything is a chemical.
7 Feb, 2019
Thankyou for your comments.
7 Feb, 2019
I would say that there isn't anything that would have been used in the last few years that would remain in the soil. Most of the ones that remain in the soil would have been banned by the EU very many years ago. Roundup or Glyphosate (weedkiller) could leave a residue for about 200 days. Lindane or Gammexane (pesticide) might have been used only if someone had a supply (that they had inherited) and that would be inert after 400 days.
6 Feb, 2019