Washington State University

Gardening in Washington State

Horticultural Oils

It is fairly easy to accidentally damage your plants or nearby environments when applying horticultural oils. Here are some important points to consider before using these oils:

juniper_PetiteHorticultural oils are non-specific so if beneficial insects get sprayed, they will die along with the insect pest.

Only spray plants with confirmed pest problems in order to conserve the beneficial insects in your garden and landscape.

Be aware that junipers and spruce often lose their blue color when oil is applied.

Oil and water do not mix: horticultural oil will inhibit oxygen transfer, which can kill fish. Keep applications and their airborne oil drift out of waterways.


For information on how to use horticultural oils successfully, see the WSU Extension fact sheet Pesticide Ingredient: Horticultural Oil.

Submitted by: Catherine Daniels, Jan. 7 2016


3 comments on “Horticultural Oils”

  1. Audrey Wright said on February 1, 2016:

    Honestly, I stay away from horticultural oils.

    I ruined half my garden, by not applying them correctly. I advise you to explore every risk free option, like populating my garden with helpful insects, attracting birds and planting resistant plants.

    Obviously, my approach would take many months, if not an year to provide a resolution, but explore organic remedies first. It’s best for your garden and you.

    • Chalker-Scott, Linda K said on February 1, 2016:

      We applaud your approach, but need to clarify that horticultural oils *are* organic remedies. They are OMRI listed products. Perhaps you meant “biological control” before chemical control? This is the first line of defense. Chemical use should always be the last resort.

      We also had to remove the link you provided, as it was not a science-based website.

      • Audrey Wright said on February 1, 2016:

        I mixed my terms, apologies 🙂

        I meant to say that I always try to nudge my garden into fixing itself, through it’s natural processes, before I load the artillery.

        Cheers !

Leave a Comment

Your email address will not be published. Required fields are marked *



Gardening in Washington State, Puyallup Research and Extension Center

All publications linked to this website have been peer-reviewed
© 2023 Washington State University | Accessibility | Policies | Copyright | Log in