I made a mix of 1:8oz neem oil: water solution to treat some indoor plants against insects occassionally. I wonder how long, if at all, this solution can be stored and remain effective? It's in a sealed bucket stored indoors and I'm thinking I can mix it well before use and simply continue to use it as long as it lasts, but I wasn't able to find info on whether or not the solution will loose its effectiveness being stored like this over time (and if so, over what timespan).

  • It is stored in the dark (a bucket with a sealed cover over it) so light is not an issue. It is already mixed with water, and the bucket was not sterile, so microbes could be an issue.
    – cr0
    May 11, 2017 at 14:40
  • Banned - wow! I didn't know that. I thought it was a fairly safe option, and occurring naturally makes me more confident it won't have unintended consequences. Apparently the EU disagrees - I'll have to look into why.
    – cr0
    May 11, 2017 at 15:21

1 Answer 1


I'm new to this substance, and have only used it once so far, after finding out it's a great solution to my current black cherry aphid (aka cherry blackfly) problem, but all of the information I have found so far says to make a fresh batch each time, and use within a few hours.

Here'a quote from www.discoverneem.com:

Use your neem insect spray as quickly as possible, definitely within eight hours. Once mixed with water the neem oil starts breaking down. Always make a fresh batch for spraying, and only prepare the amount you need.

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